diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index a189a8efc3..1145a9bdda 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3717,6 +3717,20 @@ ANY num_sync (
+ enable_incrementalsort (boolean)
+
+ enable_incrementalsort configuration parameter
+
+
+
+
+ Enables or disables the query planner's use of incremental sort
+ steps. The default is on.
+
+
+
+
enable_indexscan (boolean)
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 79f639d5e2..da9b030670 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -81,6 +81,8 @@ static void show_upper_qual(List *qual, const char *qlabel,
ExplainState *es);
static void show_sort_keys(SortState *sortstate, List *ancestors,
ExplainState *es);
+static void show_incremental_sort_keys(IncrementalSortState *incrsortstate,
+ List *ancestors, ExplainState *es);
static void show_merge_append_keys(MergeAppendState *mstate, List *ancestors,
ExplainState *es);
static void show_agg_keys(AggState *astate, List *ancestors,
@@ -94,7 +96,7 @@ static void show_grouping_set_keys(PlanState *planstate,
static void show_group_keys(GroupState *gstate, List *ancestors,
ExplainState *es);
static void show_sort_group_keys(PlanState *planstate, const char *qlabel,
- int nkeys, AttrNumber *keycols,
+ int nkeys, int nPresortedKeys, AttrNumber *keycols,
Oid *sortOperators, Oid *collations, bool *nullsFirst,
List *ancestors, ExplainState *es);
static void show_sortorder_options(StringInfo buf, Node *sortexpr,
@@ -102,6 +104,8 @@ static void show_sortorder_options(StringInfo buf, Node *sortexpr,
static void show_tablesample(TableSampleClause *tsc, PlanState *planstate,
List *ancestors, ExplainState *es);
static void show_sort_info(SortState *sortstate, ExplainState *es);
+static void show_incremental_sort_info(IncrementalSortState *incrsortstate,
+ ExplainState *es);
static void show_hash_info(HashState *hashstate, ExplainState *es);
static void show_tidbitmap_info(BitmapHeapScanState *planstate,
ExplainState *es);
@@ -1067,6 +1071,9 @@ ExplainNode(PlanState *planstate, List *ancestors,
case T_Sort:
pname = sname = "Sort";
break;
+ case T_IncrementalSort:
+ pname = sname = "Incremental Sort";
+ break;
case T_Group:
pname = sname = "Group";
break;
@@ -1677,6 +1684,12 @@ ExplainNode(PlanState *planstate, List *ancestors,
show_sort_keys(castNode(SortState, planstate), ancestors, es);
show_sort_info(castNode(SortState, planstate), es);
break;
+ case T_IncrementalSort:
+ show_incremental_sort_keys(castNode(IncrementalSortState, planstate),
+ ancestors, es);
+ show_incremental_sort_info(castNode(IncrementalSortState, planstate),
+ es);
+ break;
case T_MergeAppend:
show_merge_append_keys(castNode(MergeAppendState, planstate),
ancestors, es);
@@ -2006,12 +2019,29 @@ show_sort_keys(SortState *sortstate, List *ancestors, ExplainState *es)
Sort *plan = (Sort *) sortstate->ss.ps.plan;
show_sort_group_keys((PlanState *) sortstate, "Sort Key",
- plan->numCols, plan->sortColIdx,
+ plan->numCols, 0, plan->sortColIdx,
plan->sortOperators, plan->collations,
plan->nullsFirst,
ancestors, es);
}
+/*
+ * Show the sort keys for a IncrementalSort node.
+ */
+static void
+show_incremental_sort_keys(IncrementalSortState *incrsortstate,
+ List *ancestors, ExplainState *es)
+{
+ IncrementalSort *plan = (IncrementalSort *) incrsortstate->ss.ps.plan;
+
+ show_sort_group_keys((PlanState *) incrsortstate, "Sort Key",
+ plan->sort.numCols, plan->presortedCols,
+ plan->sort.sortColIdx,
+ plan->sort.sortOperators, plan->sort.collations,
+ plan->sort.nullsFirst,
+ ancestors, es);
+}
+
/*
* Likewise, for a MergeAppend node.
*/
@@ -2022,7 +2052,7 @@ show_merge_append_keys(MergeAppendState *mstate, List *ancestors,
MergeAppend *plan = (MergeAppend *) mstate->ps.plan;
show_sort_group_keys((PlanState *) mstate, "Sort Key",
- plan->numCols, plan->sortColIdx,
+ plan->numCols, 0, plan->sortColIdx,
plan->sortOperators, plan->collations,
plan->nullsFirst,
ancestors, es);
@@ -2046,7 +2076,7 @@ show_agg_keys(AggState *astate, List *ancestors,
show_grouping_sets(outerPlanState(astate), plan, ancestors, es);
else
show_sort_group_keys(outerPlanState(astate), "Group Key",
- plan->numCols, plan->grpColIdx,
+ plan->numCols, 0, plan->grpColIdx,
NULL, NULL, NULL,
ancestors, es);
@@ -2115,7 +2145,7 @@ show_grouping_set_keys(PlanState *planstate,
if (sortnode)
{
show_sort_group_keys(planstate, "Sort Key",
- sortnode->numCols, sortnode->sortColIdx,
+ sortnode->numCols, 0, sortnode->sortColIdx,
sortnode->sortOperators, sortnode->collations,
sortnode->nullsFirst,
ancestors, es);
@@ -2172,7 +2202,7 @@ show_group_keys(GroupState *gstate, List *ancestors,
/* The key columns refer to the tlist of the child plan */
ancestors = lcons(gstate, ancestors);
show_sort_group_keys(outerPlanState(gstate), "Group Key",
- plan->numCols, plan->grpColIdx,
+ plan->numCols, 0, plan->grpColIdx,
NULL, NULL, NULL,
ancestors, es);
ancestors = list_delete_first(ancestors);
@@ -2185,13 +2215,14 @@ show_group_keys(GroupState *gstate, List *ancestors,
*/
static void
show_sort_group_keys(PlanState *planstate, const char *qlabel,
- int nkeys, AttrNumber *keycols,
+ int nkeys, int nPresortedKeys, AttrNumber *keycols,
Oid *sortOperators, Oid *collations, bool *nullsFirst,
List *ancestors, ExplainState *es)
{
Plan *plan = planstate->plan;
List *context;
List *result = NIL;
+ List *resultPresorted = NIL;
StringInfoData sortkeybuf;
bool useprefix;
int keyno;
@@ -2231,9 +2262,13 @@ show_sort_group_keys(PlanState *planstate, const char *qlabel,
nullsFirst[keyno]);
/* Emit one property-list item per sort key */
result = lappend(result, pstrdup(sortkeybuf.data));
+ if (keyno < nPresortedKeys)
+ resultPresorted = lappend(resultPresorted, exprstr);
}
ExplainPropertyList(qlabel, result, es);
+ if (nPresortedKeys > 0)
+ ExplainPropertyList("Presorted Key", resultPresorted, es);
}
/*
@@ -2441,6 +2476,95 @@ show_sort_info(SortState *sortstate, ExplainState *es)
}
}
+/*
+ * If it's EXPLAIN ANALYZE, show tuplesort stats for a incremental sort node
+ */
+static void
+show_incremental_sort_info(IncrementalSortState *incrsortstate,
+ ExplainState *es)
+{
+ if (es->analyze && incrsortstate->sort_Done &&
+ incrsortstate->tuplesortstate != NULL)
+ {
+ Tuplesortstate *state = (Tuplesortstate *) incrsortstate->tuplesortstate;
+ TuplesortInstrumentation stats;
+ const char *sortMethod;
+ const char *spaceType;
+ long spaceUsed;
+
+ tuplesort_get_stats(state, &stats);
+ sortMethod = tuplesort_method_name(stats.sortMethod);
+ spaceType = tuplesort_space_type_name(stats.spaceType);
+ spaceUsed = stats.spaceUsed;
+
+ if (es->format == EXPLAIN_FORMAT_TEXT)
+ {
+ appendStringInfoSpaces(es->str, es->indent * 2);
+ appendStringInfo(es->str, "Sort Method: %s %s: %ldkB\n",
+ sortMethod, spaceType, spaceUsed);
+ appendStringInfoSpaces(es->str, es->indent * 2);
+ appendStringInfo(es->str, "Sort Groups: %ld\n",
+ incrsortstate->group_count);
+ }
+ else
+ {
+ ExplainPropertyText("Sort Method", sortMethod, es);
+ ExplainPropertyInteger("Sort Space Used", "kB", spaceUsed, es);
+ ExplainPropertyText("Sort Space Type", spaceType, es);
+ ExplainPropertyInteger("Sort Groups:", NULL,
+ incrsortstate->group_count, es);
+ }
+ }
+
+ if (incrsortstate->shared_info != NULL)
+ {
+ int n;
+ bool opened_group = false;
+
+ for (n = 0; n < incrsortstate->shared_info->num_workers; n++)
+ {
+ TuplesortInstrumentation *sinstrument;
+ const char *sortMethod;
+ const char *spaceType;
+ long spaceUsed;
+ int64 group_count;
+
+ sinstrument = &incrsortstate->shared_info->sinfo[n].sinstrument;
+ group_count = incrsortstate->shared_info->sinfo[n].group_count;
+ if (sinstrument->sortMethod == SORT_TYPE_STILL_IN_PROGRESS)
+ continue; /* ignore any unfilled slots */
+ sortMethod = tuplesort_method_name(sinstrument->sortMethod);
+ spaceType = tuplesort_space_type_name(sinstrument->spaceType);
+ spaceUsed = sinstrument->spaceUsed;
+
+ if (es->format == EXPLAIN_FORMAT_TEXT)
+ {
+ appendStringInfoSpaces(es->str, es->indent * 2);
+ appendStringInfo(es->str,
+ "Worker %d: Sort Method: %s %s: %ldkB Groups: %ld\n",
+ n, sortMethod, spaceType, spaceUsed, group_count);
+ }
+ else
+ {
+ if (!opened_group)
+ {
+ ExplainOpenGroup("Workers", "Workers", false, es);
+ opened_group = true;
+ }
+ ExplainOpenGroup("Worker", NULL, true, es);
+ ExplainPropertyInteger("Worker Number", NULL, n, es);
+ ExplainPropertyText("Sort Method", sortMethod, es);
+ ExplainPropertyInteger("Sort Space Used", "kB", spaceUsed, es);
+ ExplainPropertyText("Sort Space Type", spaceType, es);
+ ExplainPropertyInteger("Sort Groups", NULL, group_count, es);
+ ExplainCloseGroup("Worker", NULL, true, es);
+ }
+ }
+ if (opened_group)
+ ExplainCloseGroup("Workers", "Workers", false, es);
+ }
+}
+
/*
* Show information on hash buckets/batches.
*/
diff --git a/src/backend/executor/Makefile b/src/backend/executor/Makefile
index 76d87eea49..c2f06da4e5 100644
--- a/src/backend/executor/Makefile
+++ b/src/backend/executor/Makefile
@@ -24,8 +24,8 @@ OBJS = execAmi.o execCurrent.o execExpr.o execExprInterp.o \
nodeLimit.o nodeLockRows.o nodeGatherMerge.o \
nodeMaterial.o nodeMergeAppend.o nodeMergejoin.o nodeModifyTable.o \
nodeNestloop.o nodeProjectSet.o nodeRecursiveunion.o nodeResult.o \
- nodeSamplescan.o nodeSeqscan.o nodeSetOp.o nodeSort.o nodeUnique.o \
- nodeValuesscan.o \
+ nodeSamplescan.o nodeSeqscan.o nodeSetOp.o \
+ nodeSort.o nodeIncrementalSort.o nodeUnique.o nodeValuesscan.o \
nodeCtescan.o nodeNamedtuplestorescan.o nodeWorktablescan.o \
nodeGroup.o nodeSubplan.o nodeSubqueryscan.o nodeTidscan.o \
nodeForeignscan.o nodeWindowAgg.o tstoreReceiver.o tqueue.o spi.o \
diff --git a/src/backend/executor/execAmi.c b/src/backend/executor/execAmi.c
index 9e78421978..520aeefd83 100644
--- a/src/backend/executor/execAmi.c
+++ b/src/backend/executor/execAmi.c
@@ -31,6 +31,7 @@
#include "executor/nodeGroup.h"
#include "executor/nodeHash.h"
#include "executor/nodeHashjoin.h"
+#include "executor/nodeIncrementalSort.h"
#include "executor/nodeIndexonlyscan.h"
#include "executor/nodeIndexscan.h"
#include "executor/nodeLimit.h"
@@ -253,6 +254,10 @@ ExecReScan(PlanState *node)
ExecReScanSort((SortState *) node);
break;
+ case T_IncrementalSortState:
+ ExecReScanIncrementalSort((IncrementalSortState *) node);
+ break;
+
case T_GroupState:
ExecReScanGroup((GroupState *) node);
break;
@@ -525,8 +530,16 @@ ExecSupportsBackwardScan(Plan *node)
case T_CteScan:
case T_Material:
case T_Sort:
+ /* these don't evaluate tlist */
return true;
+ case T_IncrementalSort:
+ /*
+ * Unlike full sort, incremental sort keeps only a single group
+ * of tuples in memory, so it can't scan backwards.
+ */
+ return false;
+
case T_LockRows:
case T_Limit:
return ExecSupportsBackwardScan(outerPlan(node));
diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index 52f1a96db5..fc3910502b 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -32,6 +32,7 @@
#include "executor/nodeForeignscan.h"
#include "executor/nodeHash.h"
#include "executor/nodeHashjoin.h"
+#include "executor/nodeIncrementalSort.h"
#include "executor/nodeIndexscan.h"
#include "executor/nodeIndexonlyscan.h"
#include "executor/nodeSeqscan.h"
@@ -281,6 +282,10 @@ ExecParallelEstimate(PlanState *planstate, ExecParallelEstimateContext *e)
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecSortEstimate((SortState *) planstate, e->pcxt);
break;
+ case T_IncrementalSortState:
+ /* even when not parallel-aware, for EXPLAIN ANALYZE */
+ ExecIncrementalSortEstimate((IncrementalSortState *) planstate, e->pcxt);
+ break;
default:
break;
@@ -494,6 +499,10 @@ ExecParallelInitializeDSM(PlanState *planstate,
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecSortInitializeDSM((SortState *) planstate, d->pcxt);
break;
+ case T_IncrementalSortState:
+ /* even when not parallel-aware, for EXPLAIN ANALYZE */
+ ExecIncrementalSortInitializeDSM((IncrementalSortState *) planstate, d->pcxt);
+ break;
default:
break;
@@ -918,6 +927,7 @@ ExecParallelReInitializeDSM(PlanState *planstate,
break;
case T_HashState:
case T_SortState:
+ case T_IncrementalSortState:
/* these nodes have DSM state, but no reinitialization is required */
break;
@@ -978,6 +988,9 @@ ExecParallelRetrieveInstrumentation(PlanState *planstate,
case T_SortState:
ExecSortRetrieveInstrumentation((SortState *) planstate);
break;
+ case T_IncrementalSortState:
+ ExecIncrementalSortRetrieveInstrumentation((IncrementalSortState *) planstate);
+ break;
case T_HashState:
ExecHashRetrieveInstrumentation((HashState *) planstate);
break;
@@ -1227,6 +1240,11 @@ ExecParallelInitializeWorker(PlanState *planstate, ParallelWorkerContext *pwcxt)
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecSortInitializeWorker((SortState *) planstate, pwcxt);
break;
+ case T_IncrementalSortState:
+ /* even when not parallel-aware, for EXPLAIN ANALYZE */
+ ExecIncrementalSortInitializeWorker((IncrementalSortState *) planstate,
+ pwcxt);
+ break;
default:
break;
diff --git a/src/backend/executor/execProcnode.c b/src/backend/executor/execProcnode.c
index a3fb4495d2..943ca65372 100644
--- a/src/backend/executor/execProcnode.c
+++ b/src/backend/executor/execProcnode.c
@@ -88,6 +88,7 @@
#include "executor/nodeGroup.h"
#include "executor/nodeHash.h"
#include "executor/nodeHashjoin.h"
+#include "executor/nodeIncrementalSort.h"
#include "executor/nodeIndexonlyscan.h"
#include "executor/nodeIndexscan.h"
#include "executor/nodeLimit.h"
@@ -314,6 +315,11 @@ ExecInitNode(Plan *node, EState *estate, int eflags)
estate, eflags);
break;
+ case T_IncrementalSort:
+ result = (PlanState *) ExecInitIncrementalSort((IncrementalSort *) node,
+ estate, eflags);
+ break;
+
case T_Group:
result = (PlanState *) ExecInitGroup((Group *) node,
estate, eflags);
@@ -695,6 +701,10 @@ ExecEndNode(PlanState *node)
ExecEndSort((SortState *) node);
break;
+ case T_IncrementalSortState:
+ ExecEndIncrementalSort((IncrementalSortState *) node);
+ break;
+
case T_GroupState:
ExecEndGroup((GroupState *) node);
break;
diff --git a/src/backend/executor/nodeIncrementalSort.c b/src/backend/executor/nodeIncrementalSort.c
new file mode 100644
index 0000000000..0fbb63d4b2
--- /dev/null
+++ b/src/backend/executor/nodeIncrementalSort.c
@@ -0,0 +1,681 @@
+/*-------------------------------------------------------------------------
+ *
+ * nodeIncremenalSort.c
+ * Routines to handle incremental sorting of relations.
+ *
+ * DESCRIPTION
+ *
+ * Incremental sort is an optimized variant of multikey sort for cases
+ * when the input is already sorted by a prefix of the sort keys. For
+ * example when a sort by (key1, key2 ... keyN) is requested, and the
+ * input is already sorted by (key1, key2 ... keyM), M < N, we can
+ * divide the input into groups where keys (key1, ... keyM) are equal,
+ * and only sort on the remaining columns.
+ *
+ * Consider the following example. We have input tuples consisting of
+ * two integers (X, Y) already presorted by X, while it's required to
+ * sort them by both X and Y. Let input tuples be following.
+ *
+ * (1, 5)
+ * (1, 2)
+ * (2, 9)
+ * (2, 1)
+ * (2, 5)
+ * (3, 3)
+ * (3, 7)
+ *
+ * Incremental sort algorithm would split the input into the following
+ * groups, which have equal X, and then sort them by Y individually:
+ *
+ * (1, 5) (1, 2)
+ * (2, 9) (2, 1) (2, 5)
+ * (3, 3) (3, 7)
+ *
+ * After sorting these groups and putting them altogether, we would get
+ * the following result which is sorted by X and Y, as requested:
+ *
+ * (1, 2)
+ * (1, 5)
+ * (2, 1)
+ * (2, 5)
+ * (2, 9)
+ * (3, 3)
+ * (3, 7)
+ *
+ * Incremental sort may be more efficient than plain sort, parcitularly
+ * on large datasets, as it reduces the amount of data to sort at once,
+ * making it more likely it fits into work_mem (eliminating the need to
+ * spill to disk). But the main advantage of incremental sort is that
+ * it can start producing rows early, before sorting the whole dataset,
+ * which is a significant benefit especially for queries with LIMIT.
+ *
+ * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ * src/backend/executor/nodeIncremenalSort.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "executor/execdebug.h"
+#include "executor/nodeIncrementalSort.h"
+#include "miscadmin.h"
+#include "utils/lsyscache.h"
+#include "utils/tuplesort.h"
+
+/*
+ * Prepare information for presorted_keys comparison.
+ */
+static void
+preparePresortedCols(IncrementalSortState *node)
+{
+ IncrementalSort *plannode = (IncrementalSort *) node->ss.ps.plan;
+ int presortedCols,
+ i;
+
+ Assert(IsA(plannode, IncrementalSort));
+ presortedCols = plannode->presortedCols;
+
+ node->presorted_keys = (PresortedKeyData *) palloc(presortedCols *
+ sizeof(PresortedKeyData));
+
+ for (i = 0; i < presortedCols; i++)
+ {
+ Oid equalityOp,
+ equalityFunc;
+ PresortedKeyData *key;
+
+ key = &node->presorted_keys[i];
+ key->attno = plannode->sort.sortColIdx[i];
+
+ equalityOp = get_equality_op_for_ordering_op(
+ plannode->sort.sortOperators[i], NULL);
+ if (!OidIsValid(equalityOp))
+ elog(ERROR, "missing equality operator for ordering operator %u",
+ plannode->sort.sortOperators[i]);
+
+ equalityFunc = get_opcode(equalityOp);
+ if (!OidIsValid(equalityFunc))
+ elog(ERROR, "missing function for operator %u", equalityOp);
+
+ /* Lookup the comparison function */
+ fmgr_info_cxt(equalityFunc, &key->flinfo, CurrentMemoryContext);
+
+ /* We can initialize the callinfo just once and re-use it */
+ InitFunctionCallInfoData(key->fcinfo, &key->flinfo, 2,
+ plannode->sort.collations[i], NULL, NULL);
+ key->fcinfo.argnull[0] = false;
+ key->fcinfo.argnull[1] = false;
+ }
+}
+
+/*
+ * Check whether a given tuple belongs to the current sort group.
+ *
+ * We do this by comparing its first 'presortedCols' column values to
+ * the pivot tuple of the current group.
+ *
+ */
+static bool
+isCurrentGroup(IncrementalSortState *node, TupleTableSlot *tupleSlot)
+{
+ int presortedCols, i;
+ TupleTableSlot *group_pivot = node->group_pivot;
+
+ Assert(IsA(node->ss.ps.plan, IncrementalSort));
+
+ presortedCols = ((IncrementalSort *) node->ss.ps.plan)->presortedCols;
+
+ /*
+ * We do assume the input is sorted by keys (0, ... n), which means
+ * the tail keys are more likely to change. So we do the comparison
+ * from the end, to minimize the number of function calls.
+ */
+ for (i = presortedCols - 1; i >= 0; i--)
+ {
+ Datum datumA,
+ datumB,
+ result;
+ bool isnullA,
+ isnullB;
+ AttrNumber attno = node->presorted_keys[i].attno;
+ PresortedKeyData *key;
+
+ datumA = slot_getattr(group_pivot, attno, &isnullA);
+ datumB = slot_getattr(tupleSlot, attno, &isnullB);
+
+ /* Special case for NULL-vs-NULL, else use standard comparison */
+ if (isnullA || isnullB)
+ {
+ if (isnullA == isnullB)
+ continue;
+ else
+ return false;
+ }
+
+ key = &node->presorted_keys[i];
+
+ key->fcinfo.arg[0] = datumA;
+ key->fcinfo.arg[1] = datumB;
+
+ /* just for paranoia's sake, we reset isnull each time */
+ key->fcinfo.isnull = false;
+
+ result = FunctionCallInvoke(&key->fcinfo);
+
+ /* Check for null result, since caller is clearly not expecting one */
+ if (key->fcinfo.isnull)
+ elog(ERROR, "function %u returned NULL", key->flinfo.fn_oid);
+
+ if (!DatumGetBool(result))
+ return false;
+ }
+ return true;
+}
+
+/*
+ * Sorting many small groups with tuplesort is inefficient. In order to
+ * cope with this problem we don't start a new group until the current one
+ * contains at least DEFAULT_MIN_GROUP_SIZE tuples. However, in the case
+ * of bounded sort where bound is less than DEFAULT_MIN_GROUP_SIZE we start
+ * looking for the new group when bound is done.
+ */
+#define DEFAULT_MIN_GROUP_SIZE 32
+
+/* ----------------------------------------------------------------
+ * ExecIncrementalSort
+ *
+ * Assuming that outer subtree returns tuple presorted by some prefix
+ * of target sort columns, performs incremental sort. It fetches
+ * groups of tuples where prefix sort columns are equal and sorts them
+ * using tuplesort. This approach allows to evade sorting of whole
+ * dataset. Besides taking less memory and being faster, it allows to
+ * start returning tuples before fetching full dataset from outer
+ * subtree.
+ *
+ * Conditions:
+ * -- none.
+ *
+ * Initial States:
+ * -- the outer child is prepared to return the first tuple.
+ * ----------------------------------------------------------------
+ */
+static TupleTableSlot *
+ExecIncrementalSort(PlanState *pstate)
+{
+ IncrementalSortState *node = castNode(IncrementalSortState, pstate);
+ EState *estate;
+ ScanDirection dir;
+ Tuplesortstate *tuplesortstate;
+ TupleTableSlot *slot;
+ IncrementalSort *plannode = (IncrementalSort *) node->ss.ps.plan;
+ PlanState *outerNode;
+ TupleDesc tupDesc;
+ int64 nTuples = 0;
+ int64 minGroupSize;
+
+ CHECK_FOR_INTERRUPTS();
+
+ /*
+ * get state info from node
+ */
+ SO1_printf("ExecIncrementalSort: %s\n",
+ "entering routine");
+
+ estate = node->ss.ps.state;
+ dir = estate->es_direction;
+ tuplesortstate = (Tuplesortstate *) node->tuplesortstate;
+
+ /*
+ * Return next tuple from the current sorted group set if available.
+ * If there are no more tuples in the current group, we need to try
+ * to fetch more tuples from the input and build another group.
+ */
+ if (node->sort_Done)
+ {
+ slot = node->ss.ps.ps_ResultTupleSlot;
+ if (tuplesort_gettupleslot(tuplesortstate,
+ ScanDirectionIsForward(dir),
+ false, slot, NULL) || node->finished)
+ return slot;
+ }
+
+ /*
+ * First time through or no tuples in the current group. Read next
+ * batch of tuples from the outer plan and pass them to tuplesort.c.
+ * Subsequent calls just fetch tuples from tuplesort, until the group
+ * is exhausted, at which point we build the next group.
+ */
+
+ SO1_printf("ExecIncrementalSort: %s\n",
+ "sorting subplan");
+
+ /*
+ * Want to scan subplan in the forward direction while creating the
+ * sorted data.
+ */
+ estate->es_direction = ForwardScanDirection;
+
+ outerNode = outerPlanState(node);
+ tupDesc = ExecGetResultType(outerNode);
+
+ /*
+ * Initialize tuplesort module (needed only before the first group).
+ */
+ if (node->tuplesortstate == NULL)
+ {
+ /*
+ * We are going to process the first group of presorted data.
+ * Initialize support structures for cmpSortPresortedCols - already
+ * sorted columns.
+ */
+ preparePresortedCols(node);
+
+ SO1_printf("ExecIncrementalSort: %s\n",
+ "calling tuplesort_begin_heap");
+
+ /*
+ * Pass all the columns to tuplesort. We pass to tuple sort groups
+ * of at least minGroupSize size. Thus, these groups doesn't
+ * necessary have equal value of the first column.
+ */
+ tuplesortstate = tuplesort_begin_heap(
+ tupDesc,
+ plannode->sort.numCols,
+ plannode->sort.sortColIdx,
+ plannode->sort.sortOperators,
+ plannode->sort.collations,
+ plannode->sort.nullsFirst,
+ work_mem,
+ NULL,
+ false);
+ node->tuplesortstate = (void *) tuplesortstate;
+ }
+ else
+ {
+ /* Next group of presorted data */
+ tuplesort_reset((Tuplesortstate *) node->tuplesortstate);
+ }
+ node->group_count++;
+
+ /*
+ * Calculate remaining bound for bounded sort and minimal group size
+ * accordingly.
+ */
+ if (node->bounded)
+ {
+ tuplesort_set_bound(tuplesortstate, node->bound - node->bound_Done);
+ minGroupSize = Min(DEFAULT_MIN_GROUP_SIZE, node->bound - node->bound_Done);
+ }
+ else
+ {
+ minGroupSize = DEFAULT_MIN_GROUP_SIZE;
+ }
+
+ /* If we got a leftover tuple from the last group, pass it to tuplesort. */
+ if (!TupIsNull(node->group_pivot))
+ {
+ tuplesort_puttupleslot(tuplesortstate, node->group_pivot);
+ ExecClearTuple(node->group_pivot);
+ nTuples++;
+ }
+
+ /*
+ * Put next group of tuples where presortedCols sort values are equal to
+ * tuplesort.
+ */
+ for (;;)
+ {
+ slot = ExecProcNode(outerNode);
+
+ if (TupIsNull(slot))
+ {
+ node->finished = true;
+ break;
+ }
+
+ /*
+ * Accumulate the next group of presorted tuples for tuplesort.
+ * We always accumulate at least minGroupSize tuples, and only
+ * then we start to compare the prefix keys.
+ *
+ * The last tuple is kept as a pivot, so that we can determine if
+ * the subsequent tuples have the same prefix key (same group).
+ */
+ if (nTuples < minGroupSize)
+ {
+ tuplesort_puttupleslot(tuplesortstate, slot);
+
+ /* Keep the last tuple in minimal group as a pivot. */
+ if (nTuples == minGroupSize - 1)
+ ExecCopySlot(node->group_pivot, slot);
+ nTuples++;
+ }
+ else
+ {
+ /*
+ * Iterate while presorted cols are the same as in the pivot
+ * tuple.
+ *
+ * After accumulating at least minGroupSize tuples (we don't
+ * know how many groups are there in that set), we need to keep
+ * accumulating until we reach the end of the group. Only then
+ * we can do the sort and output all the tuples.
+ *
+ * We compare the prefix keys to the pivot - if the prefix keys
+ * are the same the tuple belongs to the same group, so we pass
+ * it to the tuplesort.
+ *
+ * If the prefix differs, we've reached the end of the group. We
+ * need to keep the last tuple, so we copy it into the pivot slot
+ * (it does not serve as pivot, though).
+ */
+ if (isCurrentGroup(node, slot))
+ {
+ tuplesort_puttupleslot(tuplesortstate, slot);
+ nTuples++;
+ }
+ else
+ {
+ ExecCopySlot(node->group_pivot, slot);
+ break;
+ }
+ }
+ }
+
+ /*
+ * Complete the sort.
+ */
+ tuplesort_performsort(tuplesortstate);
+
+ /*
+ * restore to user specified direction
+ */
+ estate->es_direction = dir;
+
+ /*
+ * finally set the sorted flag to true
+ */
+ node->sort_Done = true;
+ node->bounded_Done = node->bounded;
+ if (node->shared_info && node->am_worker)
+ {
+ TuplesortInstrumentation *si;
+
+ Assert(IsParallelWorker());
+ Assert(ParallelWorkerNumber <= node->shared_info->num_workers);
+ si = &node->shared_info->sinfo[ParallelWorkerNumber].sinstrument;
+ tuplesort_get_stats(tuplesortstate, si);
+ node->shared_info->sinfo[ParallelWorkerNumber].group_count =
+ node->group_count;
+ }
+
+ /*
+ * Adjust bound_Done with number of tuples we've actually sorted.
+ */
+ if (node->bounded)
+ {
+ if (node->finished)
+ node->bound_Done = node->bound;
+ else
+ node->bound_Done = Min(node->bound, node->bound_Done + nTuples);
+ }
+
+ SO1_printf("ExecIncrementalSort: %s\n", "sorting done");
+
+ SO1_printf("ExecIncrementalSort: %s\n",
+ "retrieving tuple from tuplesort");
+
+ /*
+ * Get the first or next tuple from tuplesort. Returns NULL if no more
+ * tuples.
+ */
+ slot = node->ss.ps.ps_ResultTupleSlot;
+ (void) tuplesort_gettupleslot(tuplesortstate,
+ ScanDirectionIsForward(dir),
+ false, slot, NULL);
+ return slot;
+}
+
+/* ----------------------------------------------------------------
+ * ExecInitIncrementalSort
+ *
+ * Creates the run-time state information for the sort node
+ * produced by the planner and initializes its outer subtree.
+ * ----------------------------------------------------------------
+ */
+IncrementalSortState *
+ExecInitIncrementalSort(IncrementalSort *node, EState *estate, int eflags)
+{
+ IncrementalSortState *incrsortstate;
+
+ SO1_printf("ExecInitIncrementalSort: %s\n",
+ "initializing sort node");
+
+ /*
+ * Incremental sort can't be used with either EXEC_FLAG_REWIND,
+ * EXEC_FLAG_BACKWARD or EXEC_FLAG_MARK, because we hold only current
+ * bucket in tuplesortstate.
+ */
+ Assert((eflags & (EXEC_FLAG_REWIND |
+ EXEC_FLAG_BACKWARD |
+ EXEC_FLAG_MARK)) == 0);
+
+ /*
+ * create state structure
+ */
+ incrsortstate = makeNode(IncrementalSortState);
+ incrsortstate->ss.ps.plan = (Plan *) node;
+ incrsortstate->ss.ps.state = estate;
+ incrsortstate->ss.ps.ExecProcNode = ExecIncrementalSort;
+
+ incrsortstate->bounded = false;
+ incrsortstate->sort_Done = false;
+ incrsortstate->finished = false;
+ incrsortstate->tuplesortstate = NULL;
+ incrsortstate->group_pivot = NULL;
+ incrsortstate->bound_Done = 0;
+ incrsortstate->group_count = 0;
+ incrsortstate->presorted_keys = NULL;
+
+ /*
+ * Miscellaneous initialization
+ *
+ * Sort nodes don't initialize their ExprContexts because they never call
+ * ExecQual or ExecProject.
+ */
+
+ /*
+ * initialize child nodes
+ *
+ * We shield the child node from the need to support REWIND, BACKWARD, or
+ * MARK/RESTORE.
+ */
+ eflags &= ~(EXEC_FLAG_REWIND | EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK);
+
+ outerPlanState(incrsortstate) = ExecInitNode(outerPlan(node), estate, eflags);
+
+ /*
+ * Initialize scan slot and type.
+ */
+ ExecCreateScanSlotFromOuterPlan(estate, &incrsortstate->ss);
+
+ /*
+ * Initialize return slot and type. No need to initialize projection info because
+ * this node doesn't do projections.
+ */
+ ExecInitResultTupleSlotTL(estate, &incrsortstate->ss.ps);
+ incrsortstate->ss.ps.ps_ProjInfo = NULL;
+
+ /* make standalone slot to store previous tuple from outer node */
+ incrsortstate->group_pivot = MakeSingleTupleTableSlot(
+ ExecGetResultType(outerPlanState(incrsortstate)));
+
+ SO1_printf("ExecInitIncrementalSort: %s\n",
+ "sort node initialized");
+
+ return incrsortstate;
+}
+
+/* ----------------------------------------------------------------
+ * ExecEndIncrementalSort(node)
+ * ----------------------------------------------------------------
+ */
+void
+ExecEndIncrementalSort(IncrementalSortState *node)
+{
+ SO1_printf("ExecEndIncrementalSort: %s\n",
+ "shutting down sort node");
+
+ /*
+ * clean out the tuple table
+ */
+ ExecClearTuple(node->ss.ss_ScanTupleSlot);
+ /* must drop pointer to sort result tuple */
+ ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
+ /* must drop stanalone tuple slot from outer node */
+ ExecDropSingleTupleTableSlot(node->group_pivot);
+
+ /*
+ * Release tuplesort resources
+ */
+ if (node->tuplesortstate != NULL)
+ tuplesort_end((Tuplesortstate *) node->tuplesortstate);
+ node->tuplesortstate = NULL;
+
+ /*
+ * shut down the subplan
+ */
+ ExecEndNode(outerPlanState(node));
+
+ SO1_printf("ExecEndIncrementalSort: %s\n",
+ "sort node shutdown");
+}
+
+void
+ExecReScanIncrementalSort(IncrementalSortState *node)
+{
+ PlanState *outerPlan = outerPlanState(node);
+
+ /*
+ * If we haven't sorted yet, just return. If outerplan's chgParam is not
+ * NULL then it will be re-scanned by ExecProcNode, else no reason to
+ * re-scan it at all.
+ */
+ if (!node->sort_Done)
+ return;
+
+ /* must drop pointer to sort result tuple */
+ ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
+
+ /*
+ * If subnode is to be rescanned then we forget previous sort results; we
+ * have to re-read the subplan and re-sort. Also must re-sort if the
+ * bounded-sort parameters changed or we didn't select randomAccess.
+ *
+ * Otherwise we can just rewind and rescan the sorted output.
+ */
+ node->sort_Done = false;
+ tuplesort_end((Tuplesortstate *) node->tuplesortstate);
+ node->tuplesortstate = NULL;
+ node->bound_Done = 0;
+
+ /*
+ * if chgParam of subnode is not null then plan will be re-scanned by
+ * first ExecProcNode.
+ */
+ if (outerPlan->chgParam == NULL)
+ ExecReScan(outerPlan);
+}
+
+/* ----------------------------------------------------------------
+ * Parallel Query Support
+ * ----------------------------------------------------------------
+ */
+
+/* ----------------------------------------------------------------
+ * ExecSortEstimate
+ *
+ * Estimate space required to propagate sort statistics.
+ * ----------------------------------------------------------------
+ */
+void
+ExecIncrementalSortEstimate(IncrementalSortState *node, ParallelContext *pcxt)
+{
+ Size size;
+
+ /* don't need this if not instrumenting or no workers */
+ if (!node->ss.ps.instrument || pcxt->nworkers == 0)
+ return;
+
+ size = mul_size(pcxt->nworkers, sizeof(IncrementalSortInfo));
+ size = add_size(size, offsetof(SharedIncrementalSortInfo, sinfo));
+ shm_toc_estimate_chunk(&pcxt->estimator, size);
+ shm_toc_estimate_keys(&pcxt->estimator, 1);
+}
+
+/* ----------------------------------------------------------------
+ * ExecSortInitializeDSM
+ *
+ * Initialize DSM space for sort statistics.
+ * ----------------------------------------------------------------
+ */
+void
+ExecIncrementalSortInitializeDSM(IncrementalSortState *node, ParallelContext *pcxt)
+{
+ Size size;
+
+ /* don't need this if not instrumenting or no workers */
+ if (!node->ss.ps.instrument || pcxt->nworkers == 0)
+ return;
+
+ size = offsetof(SharedIncrementalSortInfo, sinfo)
+ + pcxt->nworkers * sizeof(IncrementalSortInfo);
+ node->shared_info = shm_toc_allocate(pcxt->toc, size);
+ /* ensure any unfilled slots will contain zeroes */
+ memset(node->shared_info, 0, size);
+ node->shared_info->num_workers = pcxt->nworkers;
+ shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id,
+ node->shared_info);
+}
+
+/* ----------------------------------------------------------------
+ * ExecSortInitializeWorker
+ *
+ * Attach worker to DSM space for sort statistics.
+ * ----------------------------------------------------------------
+ */
+void
+ExecIncrementalSortInitializeWorker(IncrementalSortState *node, ParallelWorkerContext *pwcxt)
+{
+ node->shared_info =
+ shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, true);
+ node->am_worker = true;
+}
+
+/* ----------------------------------------------------------------
+ * ExecSortRetrieveInstrumentation
+ *
+ * Transfer sort statistics from DSM to private memory.
+ * ----------------------------------------------------------------
+ */
+void
+ExecIncrementalSortRetrieveInstrumentation(IncrementalSortState *node)
+{
+ Size size;
+ SharedIncrementalSortInfo *si;
+
+ if (node->shared_info == NULL)
+ return;
+
+ size = offsetof(SharedIncrementalSortInfo, sinfo)
+ + node->shared_info->num_workers * sizeof(IncrementalSortInfo);
+ si = palloc(size);
+ memcpy(si, node->shared_info, size);
+ node->shared_info = si;
+}
diff --git a/src/backend/executor/nodeSort.c b/src/backend/executor/nodeSort.c
index 73f16c9aba..bdab33f5c4 100644
--- a/src/backend/executor/nodeSort.c
+++ b/src/backend/executor/nodeSort.c
@@ -93,7 +93,8 @@ ExecSort(PlanState *pstate)
plannode->collations,
plannode->nullsFirst,
work_mem,
- NULL, node->randomAccess);
+ NULL,
+ node->randomAccess);
if (node->bounded)
tuplesort_set_bound(tuplesortstate, node->bound);
node->tuplesortstate = (void *) tuplesortstate;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 9287baaedc..9b117f7f05 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -924,6 +924,24 @@ _copyMaterial(const Material *from)
}
+/*
+ * CopySortFields
+ *
+ * This function copies the fields of the Sort node. It is used by
+ * all the copy functions for classes which inherit from Sort.
+ */
+static void
+CopySortFields(const Sort *from, Sort *newnode)
+{
+ CopyPlanFields((const Plan *) from, (Plan *) newnode);
+
+ COPY_SCALAR_FIELD(numCols);
+ COPY_POINTER_FIELD(sortColIdx, from->numCols * sizeof(AttrNumber));
+ COPY_POINTER_FIELD(sortOperators, from->numCols * sizeof(Oid));
+ COPY_POINTER_FIELD(collations, from->numCols * sizeof(Oid));
+ COPY_POINTER_FIELD(nullsFirst, from->numCols * sizeof(bool));
+}
+
/*
* _copySort
*/
@@ -935,13 +953,29 @@ _copySort(const Sort *from)
/*
* copy node superclass fields
*/
- CopyPlanFields((const Plan *) from, (Plan *) newnode);
+ CopySortFields(from, newnode);
- COPY_SCALAR_FIELD(numCols);
- COPY_POINTER_FIELD(sortColIdx, from->numCols * sizeof(AttrNumber));
- COPY_POINTER_FIELD(sortOperators, from->numCols * sizeof(Oid));
- COPY_POINTER_FIELD(collations, from->numCols * sizeof(Oid));
- COPY_POINTER_FIELD(nullsFirst, from->numCols * sizeof(bool));
+ return newnode;
+}
+
+
+/*
+ * _copyIncrementalSort
+ */
+static IncrementalSort *
+_copyIncrementalSort(const IncrementalSort *from)
+{
+ IncrementalSort *newnode = makeNode(IncrementalSort);
+
+ /*
+ * copy node superclass fields
+ */
+ CopySortFields((const Sort *) from, (Sort *) newnode);
+
+ /*
+ * copy remainder of node
+ */
+ COPY_SCALAR_FIELD(presortedCols);
return newnode;
}
@@ -4900,6 +4934,9 @@ copyObjectImpl(const void *from)
case T_Sort:
retval = _copySort(from);
break;
+ case T_IncrementalSort:
+ retval = _copyIncrementalSort(from);
+ break;
case T_Group:
retval = _copyGroup(from);
break;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 03a91c3352..51d0e3008c 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -894,12 +894,10 @@ _outMaterial(StringInfo str, const Material *node)
}
static void
-_outSort(StringInfo str, const Sort *node)
+_outSortInfo(StringInfo str, const Sort *node)
{
int i;
- WRITE_NODE_TYPE("SORT");
-
_outPlanInfo(str, (const Plan *) node);
WRITE_INT_FIELD(numCols);
@@ -921,6 +919,24 @@ _outSort(StringInfo str, const Sort *node)
appendStringInfo(str, " %s", booltostr(node->nullsFirst[i]));
}
+static void
+_outSort(StringInfo str, const Sort *node)
+{
+ WRITE_NODE_TYPE("SORT");
+
+ _outSortInfo(str, node);
+}
+
+static void
+_outIncrementalSort(StringInfo str, const IncrementalSort *node)
+{
+ WRITE_NODE_TYPE("INCREMENTALSORT");
+
+ _outSortInfo(str, (const Sort *) node);
+
+ WRITE_INT_FIELD(presortedCols);
+}
+
static void
_outUnique(StringInfo str, const Unique *node)
{
@@ -3806,6 +3822,9 @@ outNode(StringInfo str, const void *obj)
case T_Sort:
_outSort(str, obj);
break;
+ case T_IncrementalSort:
+ _outIncrementalSort(str, obj);
+ break;
case T_Unique:
_outUnique(str, obj);
break;
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 2812dc9646..ee730bd52d 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -2134,12 +2134,13 @@ _readMaterial(void)
}
/*
- * _readSort
+ * ReadCommonSort
+ * Assign the basic stuff of all nodes that inherit from Sort
*/
-static Sort *
-_readSort(void)
+static void
+ReadCommonSort(Sort *local_node)
{
- READ_LOCALS(Sort);
+ READ_TEMP_LOCALS();
ReadCommonPlan(&local_node->plan);
@@ -2148,6 +2149,32 @@ _readSort(void)
READ_OID_ARRAY(sortOperators, local_node->numCols);
READ_OID_ARRAY(collations, local_node->numCols);
READ_BOOL_ARRAY(nullsFirst, local_node->numCols);
+}
+
+/*
+ * _readSort
+ */
+static Sort *
+_readSort(void)
+{
+ READ_LOCALS_NO_FIELDS(Sort);
+
+ ReadCommonSort(local_node);
+
+ READ_DONE();
+}
+
+/*
+ * _readIncrementalSort
+ */
+static IncrementalSort *
+_readIncrementalSort(void)
+{
+ READ_LOCALS(IncrementalSort);
+
+ ReadCommonSort(&local_node->sort);
+
+ READ_INT_FIELD(presortedCols);
READ_DONE();
}
@@ -2723,6 +2750,8 @@ parseNodeString(void)
return_value = _readMaterial();
else if (MATCH("SORT", 4))
return_value = _readSort();
+ else if (MATCH("INCREMENTALSORT", 15))
+ return_value = _readIncrementalSort();
else if (MATCH("GROUP", 5))
return_value = _readGroup();
else if (MATCH("AGG", 3))
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 65a34a255d..b13f7a68ba 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -3713,6 +3713,10 @@ print_path(PlannerInfo *root, Path *path, int indent)
ptype = "Sort";
subpath = ((SortPath *) path)->subpath;
break;
+ case T_IncrementalSortPath:
+ ptype = "IncrementalSort";
+ subpath = ((SortPath *) path)->subpath;
+ break;
case T_GroupPath:
ptype = "Group";
subpath = ((GroupPath *) path)->subpath;
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 47729de896..f6d4bec556 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -128,6 +128,7 @@ bool enable_indexonlyscan = true;
bool enable_bitmapscan = true;
bool enable_tidscan = true;
bool enable_sort = true;
+bool enable_incrementalsort = true;
bool enable_hashagg = true;
bool enable_nestloop = true;
bool enable_material = true;
@@ -1611,9 +1612,9 @@ cost_recursive_union(Path *runion, Path *nrterm, Path *rterm)
}
/*
- * cost_sort
- * Determines and returns the cost of sorting a relation, including
- * the cost of reading the input data.
+ * cost_tuplesort
+ * Determines and returns the cost of sorting a relation using tuplesort,
+ * not including the cost of reading the input data.
*
* If the total volume of data to sort is less than sort_mem, we will do
* an in-memory sort, which requires no I/O and about t*log2(t) tuple
@@ -1640,39 +1641,23 @@ cost_recursive_union(Path *runion, Path *nrterm, Path *rterm)
* specifying nonzero comparison_cost; typically that's used for any extra
* work that has to be done to prepare the inputs to the comparison operators.
*
- * 'pathkeys' is a list of sort keys
- * 'input_cost' is the total cost for reading the input data
* 'tuples' is the number of tuples in the relation
* 'width' is the average tuple width in bytes
* 'comparison_cost' is the extra cost per comparison, if any
* 'sort_mem' is the number of kilobytes of work memory allowed for the sort
* 'limit_tuples' is the bound on the number of output tuples; -1 if no bound
- *
- * NOTE: some callers currently pass NIL for pathkeys because they
- * can't conveniently supply the sort keys. Since this routine doesn't
- * currently do anything with pathkeys anyway, that doesn't matter...
- * but if it ever does, it should react gracefully to lack of key data.
- * (Actually, the thing we'd most likely be interested in is just the number
- * of sort keys, which all callers *could* supply.)
*/
-void
-cost_sort(Path *path, PlannerInfo *root,
- List *pathkeys, Cost input_cost, double tuples, int width,
+static void
+cost_tuplesort(Cost *startup_cost, Cost *run_cost,
+ double tuples, int width,
Cost comparison_cost, int sort_mem,
double limit_tuples)
{
- Cost startup_cost = input_cost;
- Cost run_cost = 0;
double input_bytes = relation_byte_size(tuples, width);
double output_bytes;
double output_tuples;
long sort_mem_bytes = sort_mem * 1024L;
- if (!enable_sort)
- startup_cost += disable_cost;
-
- path->rows = tuples;
-
/*
* We want to be sure the cost of a sort is never estimated as zero, even
* if passed-in tuple count is zero. Besides, mustn't do log(0)...
@@ -1711,7 +1696,7 @@ cost_sort(Path *path, PlannerInfo *root,
*
* Assume about N log2 N comparisons
*/
- startup_cost += comparison_cost * tuples * LOG2(tuples);
+ *startup_cost = comparison_cost * tuples * LOG2(tuples);
/* Disk costs */
@@ -1722,7 +1707,7 @@ cost_sort(Path *path, PlannerInfo *root,
log_runs = 1.0;
npageaccesses = 2.0 * npages * log_runs;
/* Assume 3/4ths of accesses are sequential, 1/4th are not */
- startup_cost += npageaccesses *
+ *startup_cost += npageaccesses *
(seq_page_cost * 0.75 + random_page_cost * 0.25);
}
else if (tuples > 2 * output_tuples || input_bytes > sort_mem_bytes)
@@ -1733,12 +1718,12 @@ cost_sort(Path *path, PlannerInfo *root,
* factor is a bit higher than for quicksort. Tweak it so that the
* cost curve is continuous at the crossover point.
*/
- startup_cost += comparison_cost * tuples * LOG2(2.0 * output_tuples);
+ *startup_cost = comparison_cost * tuples * LOG2(2.0 * output_tuples);
}
else
{
/* We'll use plain quicksort on all the input tuples */
- startup_cost += comparison_cost * tuples * LOG2(tuples);
+ *startup_cost = comparison_cost * tuples * LOG2(tuples);
}
/*
@@ -1749,8 +1734,183 @@ cost_sort(Path *path, PlannerInfo *root,
* here --- the upper LIMIT will pro-rate the run cost so we'd be double
* counting the LIMIT otherwise.
*/
- run_cost += cpu_operator_cost * tuples;
+ *run_cost = cpu_operator_cost * tuples;
+}
+/*
+ * cost_full_sort
+ * Determines and returns the cost of sorting a relation, including the
+ * cost of reading the input data.
+ *
+ * For the precise description of how the cost is calculated, see the comment
+ * for cost_tuplesort().
+ */
+void
+cost_full_sort(Cost *startup_cost, Cost *run_cost,
+ Cost input_total_cost, double tuples, int width,
+ Cost comparison_cost, int sort_mem,
+ double limit_tuples)
+{
+ cost_tuplesort(startup_cost, run_cost,
+ tuples, width,
+ comparison_cost, sort_mem,
+ limit_tuples);
+
+ if (!enable_sort)
+ *startup_cost += disable_cost;
+
+ *startup_cost += input_total_cost;
+}
+
+/*
+ * cost_incremental_sort
+ * Determines and returns the cost of sorting a relation incrementally, when
+ * the input path is already sorted by some of the pathkeys.
+ *
+ * 'presorted_keys' is the number of leading pathkeys by which the input path
+ * is sorted.
+ *
+ * We estimate the number of groups into which the relation is divided by the
+ * leading pathkeys, and then calculate the cost of sorting a single group
+ * with tuplesort using cost_tuplesort().
+ */
+void
+cost_incremental_sort(Path *path,
+ PlannerInfo *root, List *pathkeys, int presorted_keys,
+ Cost input_startup_cost, Cost input_total_cost,
+ double input_tuples, int width, Cost comparison_cost, int sort_mem,
+ double limit_tuples)
+{
+ Cost startup_cost = 0,
+ run_cost = 0,
+ input_run_cost = input_total_cost - input_startup_cost;
+ double output_tuples,
+ output_groups,
+ group_tuples,
+ input_groups;
+ Cost group_startup_cost,
+ group_run_cost,
+ group_input_run_cost;
+ List *presortedExprs = NIL;
+ ListCell *l;
+ int i = 0;
+
+ Assert(presorted_keys != 0);
+
+ if (!enable_sort)
+ startup_cost += disable_cost;
+
+ if (!enable_incrementalsort)
+ startup_cost += disable_cost;
+
+ /*
+ * We want to be sure the cost of a sort is never estimated as zero, even
+ * if passed-in tuple count is zero. Besides, mustn't do log(0)...
+ */
+ if (input_tuples < 2.0)
+ input_tuples = 2.0;
+
+ /* Extract presorted keys as list of expressions */
+ foreach(l, pathkeys)
+ {
+ PathKey *key = (PathKey *)lfirst(l);
+ EquivalenceMember *member = (EquivalenceMember *)
+ linitial(key->pk_eclass->ec_members);
+
+ presortedExprs = lappend(presortedExprs, member->em_expr);
+
+ i++;
+ if (i >= presorted_keys)
+ break;
+ }
+
+ /* Estimate number of groups with equal presorted keys */
+ input_groups = estimate_num_groups(root, presortedExprs, input_tuples, NULL);
+ group_tuples = input_tuples / input_groups;
+ group_input_run_cost = input_run_cost / input_groups;
+
+ /*
+ * Estimate average cost of sorting of one group where presorted keys
+ * are equal. Incremental sort is sensitive to distribution of tuples
+ * to the groups, where we're relying on quite rough assumptions. Thus,
+ * we're pessimistic about incremental sort performance and increase
+ * its average group size by half.
+ */
+ cost_tuplesort(&group_startup_cost, &group_run_cost,
+ 1.5 * group_tuples, width, comparison_cost, sort_mem,
+ limit_tuples);
+
+ /* If we have a LIMIT, adjust the number of groups we'll have to return. */
+ if (limit_tuples > 0 && limit_tuples < input_tuples)
+ {
+ output_tuples = limit_tuples;
+ output_groups = floor(output_tuples / group_tuples) + 1;
+ }
+ else
+ {
+ output_tuples = input_tuples;
+ output_groups = input_groups;
+ }
+
+ /*
+ * Startup cost of incremental sort is the startup cost of its first group
+ * plus the cost of its input.
+ */
+ startup_cost += group_startup_cost
+ + input_startup_cost + group_input_run_cost;
+
+ /*
+ * After we started producing tuples from the first group, the cost of
+ * producing all the tuples is given by the cost to finish processing
+ * this group, plus the total cost to process the remaining groups,
+ * plus the remaining cost of input.
+ */
+ run_cost += group_run_cost
+ + (group_run_cost + group_startup_cost) * (output_groups - 1)
+ + group_input_run_cost * (output_groups - 1);
+
+ /*
+ * Incremental sort adds some overhead by itself. Firstly, it has to
+ * detect the sort groups. This is roughly equal to one extra copy and
+ * comparison per tuple. Secondly, it has to reset the tuplesort context
+ * for every group.
+ */
+ run_cost += (cpu_tuple_cost + comparison_cost) * output_tuples;
+ run_cost += 2.0 * cpu_tuple_cost * output_groups;
+
+ path->rows = input_tuples;
+ path->startup_cost = startup_cost;
+ path->total_cost = startup_cost + run_cost;
+}
+
+/*
+ * cost_sort
+ * Determines and returns the cost of sorting a relation, including
+ * the cost of reading the input data.
+ *
+ * NOTE: some callers currently pass NIL for pathkeys because they
+ * can't conveniently supply the sort keys. Since this routine doesn't
+ * currently do anything with pathkeys anyway, that doesn't matter...
+ * but if it ever does, it should react gracefully to lack of key data.
+ * (Actually, the thing we'd most likely be interested in is just the number
+ * of sort keys, which all callers *could* supply.)
+ */
+void
+cost_sort(Path *path, PlannerInfo *root,
+ List *pathkeys, Cost input_cost, double tuples, int width,
+ Cost comparison_cost, int sort_mem,
+ double limit_tuples)
+
+{
+ Cost startup_cost;
+ Cost run_cost;
+
+ cost_full_sort(&startup_cost, &run_cost,
+ input_cost,
+ tuples, width, comparison_cost, sort_mem,
+ limit_tuples);
+
+ path->rows = tuples;
path->startup_cost = startup_cost;
path->total_cost = startup_cost + run_cost;
}
diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c
index 6d1cc3b8a0..6b2ba366c9 100644
--- a/src/backend/optimizer/path/pathkeys.c
+++ b/src/backend/optimizer/path/pathkeys.c
@@ -327,6 +327,51 @@ pathkeys_contained_in(List *keys1, List *keys2)
return false;
}
+
+/*
+ * pathkeys_common_contained_in
+ * Same as pathkeys_contained_in, but also sets length of longest
+ * common prefix of keys1 and keys2.
+ */
+bool
+pathkeys_common_contained_in(List *keys1, List *keys2, int *n_common)
+{
+ int n = 0;
+ ListCell *key1,
+ *key2;
+
+ forboth(key1, keys1, key2, keys2)
+ {
+ PathKey *pathkey1 = (PathKey *) lfirst(key1);
+ PathKey *pathkey2 = (PathKey *) lfirst(key2);
+
+ if (pathkey1 != pathkey2)
+ {
+ *n_common = n;
+ return false;
+ }
+ n++;
+ }
+
+ *n_common = n;
+ return (key1 == NULL);
+}
+
+
+/*
+ * pathkeys_common
+ * Returns length of longest common prefix of keys1 and keys2.
+ */
+int
+pathkeys_common(List *keys1, List *keys2)
+{
+ int n;
+
+ (void) pathkeys_common_contained_in(keys1, keys2, &n);
+ return n;
+}
+
+
/*
* get_cheapest_path_for_pathkeys
* Find the cheapest path (according to the specified criterion) that
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 99d0736029..34b2417c4c 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -96,6 +96,8 @@ static Plan *create_projection_plan(PlannerInfo *root,
int flags);
static Plan *inject_projection_plan(Plan *subplan, List *tlist, bool parallel_safe);
static Sort *create_sort_plan(PlannerInfo *root, SortPath *best_path, int flags);
+static IncrementalSort *create_incrementalsort_plan(PlannerInfo *root,
+ IncrementalSortPath *best_path, int flags);
static Group *create_group_plan(PlannerInfo *root, GroupPath *best_path);
static Unique *create_upper_unique_plan(PlannerInfo *root, UpperUniquePath *best_path,
int flags);
@@ -245,6 +247,10 @@ static MergeJoin *make_mergejoin(List *tlist,
static Sort *make_sort(Plan *lefttree, int numCols,
AttrNumber *sortColIdx, Oid *sortOperators,
Oid *collations, bool *nullsFirst);
+static IncrementalSort *make_incrementalsort(Plan *lefttree,
+ int numCols, int presortedCols,
+ AttrNumber *sortColIdx, Oid *sortOperators,
+ Oid *collations, bool *nullsFirst);
static Plan *prepare_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
Relids relids,
const AttrNumber *reqColIdx,
@@ -259,6 +265,8 @@ static EquivalenceMember *find_ec_member_for_tle(EquivalenceClass *ec,
Relids relids);
static Sort *make_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
Relids relids);
+static IncrementalSort *make_incrementalsort_from_pathkeys(Plan *lefttree,
+ List *pathkeys, Relids relids, int presortedCols);
static Sort *make_sort_from_groupcols(List *groupcls,
AttrNumber *grpColIdx,
Plan *lefttree);
@@ -458,6 +466,11 @@ create_plan_recurse(PlannerInfo *root, Path *best_path, int flags)
(SortPath *) best_path,
flags);
break;
+ case T_IncrementalSort:
+ plan = (Plan *) create_incrementalsort_plan(root,
+ (IncrementalSortPath *) best_path,
+ flags);
+ break;
case T_Group:
plan = (Plan *) create_group_plan(root,
(GroupPath *) best_path);
@@ -1741,6 +1754,32 @@ create_sort_plan(PlannerInfo *root, SortPath *best_path, int flags)
return plan;
}
+/*
+ * create_incrementalsort_plan
+ *
+ * Do the same as create_sort_plan, but create IncrementalSort plan.
+ */
+static IncrementalSort *
+create_incrementalsort_plan(PlannerInfo *root, IncrementalSortPath *best_path,
+ int flags)
+{
+ IncrementalSort *plan;
+ Plan *subplan;
+
+ /* See comments in create_sort_plan() above */
+ subplan = create_plan_recurse(root, best_path->spath.subpath,
+ flags | CP_SMALL_TLIST);
+ plan = make_incrementalsort_from_pathkeys(subplan,
+ best_path->spath.path.pathkeys,
+ IS_OTHER_REL(best_path->spath.subpath->parent) ?
+ best_path->spath.path.parent->relids : NULL,
+ best_path->presortedCols);
+
+ copy_generic_path_info(&plan->sort.plan, (Path *) best_path);
+
+ return plan;
+}
+
/*
* create_group_plan
*
@@ -5000,17 +5039,24 @@ static void
label_sort_with_costsize(PlannerInfo *root, Sort *plan, double limit_tuples)
{
Plan *lefttree = plan->plan.lefttree;
- Path sort_path; /* dummy for result of cost_sort */
+ Cost startup_cost,
+ run_cost;
+
+ /*
+ * This function shouldn't have to deal with IncrementalSort plans
+ * because they are only created from corresponding Path nodes.
+ */
+ Assert(IsA(plan, Sort));
- cost_sort(&sort_path, root, NIL,
+ cost_full_sort(&startup_cost, &run_cost,
lefttree->total_cost,
lefttree->plan_rows,
lefttree->plan_width,
0.0,
work_mem,
limit_tuples);
- plan->plan.startup_cost = sort_path.startup_cost;
- plan->plan.total_cost = sort_path.total_cost;
+ plan->plan.startup_cost = startup_cost;
+ plan->plan.total_cost = startup_cost + run_cost;
plan->plan.plan_rows = lefttree->plan_rows;
plan->plan.plan_width = lefttree->plan_width;
plan->plan.parallel_aware = false;
@@ -5597,9 +5643,12 @@ make_sort(Plan *lefttree, int numCols,
AttrNumber *sortColIdx, Oid *sortOperators,
Oid *collations, bool *nullsFirst)
{
- Sort *node = makeNode(Sort);
- Plan *plan = &node->plan;
+ Sort *node;
+ Plan *plan;
+ node = makeNode(Sort);
+
+ plan = &node->plan;
plan->targetlist = lefttree->targetlist;
plan->qual = NIL;
plan->lefttree = lefttree;
@@ -5613,6 +5662,37 @@ make_sort(Plan *lefttree, int numCols,
return node;
}
+/*
+ * make_incrementalsort --- basic routine to build a IncrementalSort plan node
+ *
+ * Caller must have built the sortColIdx, sortOperators, collations, and
+ * nullsFirst arrays already.
+ */
+static IncrementalSort *
+make_incrementalsort(Plan *lefttree, int numCols, int presortedCols,
+ AttrNumber *sortColIdx, Oid *sortOperators,
+ Oid *collations, bool *nullsFirst)
+{
+ IncrementalSort *node;
+ Plan *plan;
+
+ node = makeNode(IncrementalSort);
+
+ plan = &node->sort.plan;
+ plan->targetlist = lefttree->targetlist;
+ plan->qual = NIL;
+ plan->lefttree = lefttree;
+ plan->righttree = NULL;
+ node->presortedCols = presortedCols;
+ node->sort.numCols = numCols;
+ node->sort.sortColIdx = sortColIdx;
+ node->sort.sortOperators = sortOperators;
+ node->sort.collations = collations;
+ node->sort.nullsFirst = nullsFirst;
+
+ return node;
+}
+
/*
* prepare_sort_from_pathkeys
* Prepare to sort according to given pathkeys
@@ -5959,6 +6039,42 @@ make_sort_from_pathkeys(Plan *lefttree, List *pathkeys, Relids relids)
collations, nullsFirst);
}
+/*
+ * make_incrementalsort_from_pathkeys
+ * Create sort plan to sort according to given pathkeys
+ *
+ * 'lefttree' is the node which yields input tuples
+ * 'pathkeys' is the list of pathkeys by which the result is to be sorted
+ * 'relids' is the set of relations required by prepare_sort_from_pathkeys()
+ * 'presortedCols' is the number of presorted columns in input tuples
+ */
+static IncrementalSort *
+make_incrementalsort_from_pathkeys(Plan *lefttree, List *pathkeys,
+ Relids relids, int presortedCols)
+{
+ int numsortkeys;
+ AttrNumber *sortColIdx;
+ Oid *sortOperators;
+ Oid *collations;
+ bool *nullsFirst;
+
+ /* Compute sort column info, and adjust lefttree as needed */
+ lefttree = prepare_sort_from_pathkeys(lefttree, pathkeys,
+ relids,
+ NULL,
+ false,
+ &numsortkeys,
+ &sortColIdx,
+ &sortOperators,
+ &collations,
+ &nullsFirst);
+
+ /* Now build the Sort node */
+ return make_incrementalsort(lefttree, numsortkeys, presortedCols,
+ sortColIdx, sortOperators,
+ collations, nullsFirst);
+}
+
/*
* make_sort_from_sortclauses
* Create sort plan to sort according to given sortclauses
@@ -6723,6 +6839,7 @@ is_projection_capable_plan(Plan *plan)
case T_Hash:
case T_Material:
case T_Sort:
+ case T_IncrementalSort:
case T_Unique:
case T_SetOp:
case T_LockRows:
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 008492bad5..b37c4ff933 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -4840,8 +4840,8 @@ create_distinct_paths(PlannerInfo *root,
* Build a new upperrel containing Paths for ORDER BY evaluation.
*
* All paths in the result must satisfy the ORDER BY ordering.
- * The only new path we need consider is an explicit sort on the
- * cheapest-total existing path.
+ * The only new paths we need consider is an explicit full or
+ * incremental sort on the cheapest-total existing path.
*
* input_rel: contains the source-data Paths
* target: the output tlist the result Paths must emit
@@ -4880,29 +4880,58 @@ create_ordered_paths(PlannerInfo *root,
foreach(lc, input_rel->pathlist)
{
- Path *path = (Path *) lfirst(lc);
+ Path *input_path = (Path *) lfirst(lc);
+ Path *sorted_path = input_path;
bool is_sorted;
+ int presorted_keys;
+
+ is_sorted = pathkeys_common_contained_in(root->sort_pathkeys,
+ input_path->pathkeys, &presorted_keys);
- is_sorted = pathkeys_contained_in(root->sort_pathkeys,
- path->pathkeys);
- if (path == cheapest_input_path || is_sorted)
+ if (is_sorted)
{
- if (!is_sorted)
- {
- /* An explicit sort here can take advantage of LIMIT */
- path = (Path *) create_sort_path(root,
- ordered_rel,
- path,
- root->sort_pathkeys,
- limit_tuples);
- }
+ /* Use the input path as is, but add a projection step if needed */
+ if (sorted_path->pathtarget != target)
+ sorted_path = apply_projection_to_path(root, ordered_rel,
+ sorted_path, target);
+ add_path(ordered_rel, sorted_path);
+ }
+ else if (input_path == cheapest_input_path)
+ {
+ /*
+ * Sort the cheapest input path. An explicit sort here can take
+ * advantage of LIMIT.
+ */
+ sorted_path = (Path *) create_sort_path(root,
+ ordered_rel,
+ input_path,
+ root->sort_pathkeys,
+ limit_tuples);
/* Add projection step if needed */
- if (path->pathtarget != target)
- path = apply_projection_to_path(root, ordered_rel,
- path, target);
+ if (sorted_path->pathtarget != target)
+ sorted_path = apply_projection_to_path(root, ordered_rel,
+ sorted_path, target);
- add_path(ordered_rel, path);
+ add_path(ordered_rel, sorted_path);
+
+ /* Also consider incremental sort. */
+ if (presorted_keys > 0)
+ {
+ sorted_path = (Path *) create_incremental_sort_path(root,
+ ordered_rel,
+ input_path,
+ root->sort_pathkeys,
+ presorted_keys,
+ limit_tuples);
+
+ /* Add projection step if needed */
+ if (sorted_path->pathtarget != target)
+ sorted_path = apply_projection_to_path(root, ordered_rel,
+ sorted_path, target);
+
+ add_path(ordered_rel, sorted_path);
+ }
}
}
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 833a92f538..af0b720067 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -642,6 +642,7 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
case T_Hash:
case T_Material:
case T_Sort:
+ case T_IncrementalSort:
case T_Unique:
case T_SetOp:
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 83008d7661..313cad266f 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -2795,6 +2795,7 @@ finalize_plan(PlannerInfo *root, Plan *plan,
case T_Hash:
case T_Material:
case T_Sort:
+ case T_IncrementalSort:
case T_Unique:
case T_SetOp:
case T_Group:
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index 416b3f9578..dfee78c43e 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -2593,6 +2593,57 @@ create_set_projection_path(PlannerInfo *root,
return pathnode;
}
+/*
+ * create_incremental_sort_path
+ * Creates a pathnode that represents performing an incremental sort.
+ *
+ * 'rel' is the parent relation associated with the result
+ * 'subpath' is the path representing the source of data
+ * 'pathkeys' represents the desired sort order
+ * 'presorted_keys' is the number of keys by which the input path is
+ * already sorted
+ * 'limit_tuples' is the estimated bound on the number of output tuples,
+ * or -1 if no LIMIT or couldn't estimate
+ */
+SortPath *
+create_incremental_sort_path(PlannerInfo *root,
+ RelOptInfo *rel,
+ Path *subpath,
+ List *pathkeys,
+ int presorted_keys,
+ double limit_tuples)
+{
+ IncrementalSortPath *sort = makeNode(IncrementalSortPath);
+ SortPath *pathnode = &sort->spath;
+
+ pathnode->path.pathtype = T_IncrementalSort;
+ pathnode->path.parent = rel;
+ /* Sort doesn't project, so use source path's pathtarget */
+ pathnode->path.pathtarget = subpath->pathtarget;
+ /* For now, assume we are above any joins, so no parameterization */
+ pathnode->path.param_info = NULL;
+ pathnode->path.parallel_aware = false;
+ pathnode->path.parallel_safe = rel->consider_parallel &&
+ subpath->parallel_safe;
+ pathnode->path.parallel_workers = subpath->parallel_workers;
+ pathnode->path.pathkeys = pathkeys;
+
+ pathnode->subpath = subpath;
+
+ cost_incremental_sort(&pathnode->path,
+ root, pathkeys, presorted_keys,
+ subpath->startup_cost,
+ subpath->total_cost,
+ subpath->rows,
+ subpath->pathtarget->width,
+ 0.0, /* XXX comparison_cost shouldn't be 0? */
+ work_mem, limit_tuples);
+
+ sort->presortedCols = presorted_keys;
+
+ return pathnode;
+}
+
/*
* create_sort_path
* Creates a pathnode that represents performing an explicit sort.
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 71c2b4eff1..060790198a 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -873,6 +873,15 @@ static struct config_bool ConfigureNamesBool[] =
true,
NULL, NULL, NULL
},
+ {
+ {"enable_incrementalsort", PGC_USERSET, QUERY_TUNING_METHOD,
+ gettext_noop("Enables the planner's use of incremental sort steps."),
+ NULL
+ },
+ &enable_incrementalsort,
+ true,
+ NULL, NULL, NULL
+ },
{
{"enable_hashagg", PGC_USERSET, QUERY_TUNING_METHOD,
gettext_noop("Enables the planner's use of hashed aggregation plans."),
diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index e433faad86..029c43b1d5 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -125,6 +125,15 @@
#define PARALLEL_SORT(state) ((state)->shared == NULL ? 0 : \
(state)->worker >= 0 ? 1 : 2)
+/*
+ * Initial size of memtuples array. We're trying to select this size so that
+ * array don't exceed ALLOCSET_SEPARATE_THRESHOLD and overhead of allocation
+ * be possible less. However, we don't cosider array sizes less than 1024
+ *
+ */
+#define INITIAL_MEMTUPSIZE Max(1024, \
+ ALLOCSET_SEPARATE_THRESHOLD / sizeof(SortTuple) + 1)
+
/* GUC variables */
#ifdef TRACE_SORT
bool trace_sort = false;
@@ -243,6 +252,14 @@ struct Tuplesortstate
int64 allowedMem; /* total memory allowed, in bytes */
int maxTapes; /* number of tapes (Knuth's T) */
int tapeRange; /* maxTapes-1 (Knuth's P) */
+ int64 maxSpace; /* maximum amount of space occupied among sort
+ of groups, either in-memory or on-disk */
+ bool maxSpaceOnDisk; /* true when maxSpace is value for on-disk
+ space, false when it's value for in-memory
+ space */
+ TupSortStatus maxSpaceStatus; /* sort status when maxSpace was reached */
+ MemoryContext maincontext; /* memory context for tuple sort metadata
+ that persist across multiple batches */
MemoryContext sortcontext; /* memory context holding most sort data */
MemoryContext tuplecontext; /* sub-context of sortcontext for tuple data */
LogicalTapeSet *tapeset; /* logtape.c object for tapes in a temp file */
@@ -647,6 +664,8 @@ static void worker_freeze_result_tape(Tuplesortstate *state);
static void worker_nomergeruns(Tuplesortstate *state);
static void leader_takeover_tapes(Tuplesortstate *state);
static void free_sort_tuple(Tuplesortstate *state, SortTuple *stup);
+static void tuplesort_free(Tuplesortstate *state);
+static void tuplesort_updatemax(Tuplesortstate *state);
/*
* Special versions of qsort just for SortTuple objects. qsort_tuple() sorts
@@ -682,6 +701,7 @@ tuplesort_begin_common(int workMem, SortCoordinate coordinate,
bool randomAccess)
{
Tuplesortstate *state;
+ MemoryContext maincontext;
MemoryContext sortcontext;
MemoryContext tuplecontext;
MemoryContext oldcontext;
@@ -691,13 +711,21 @@ tuplesort_begin_common(int workMem, SortCoordinate coordinate,
elog(ERROR, "random access disallowed under parallel sort");
/*
- * Create a working memory context for this sort operation. All data
- * needed by the sort will live inside this context.
+ * Memory context surviving tuplesort_reset. This memory context holds
+ * data which is useful to keep while sorting multiple similar batches.
*/
- sortcontext = AllocSetContextCreate(CurrentMemoryContext,
+ maincontext = AllocSetContextCreate(CurrentMemoryContext,
"TupleSort main",
ALLOCSET_DEFAULT_SIZES);
+ /*
+ * Create a working memory context for one sort operation. The content of
+ * this context is deleted by tuplesort_reset.
+ */
+ sortcontext = AllocSetContextCreate(maincontext,
+ "TupleSort sort",
+ ALLOCSET_DEFAULT_SIZES);
+
/*
* Caller tuple (e.g. IndexTuple) memory context.
*
@@ -715,7 +743,7 @@ tuplesort_begin_common(int workMem, SortCoordinate coordinate,
* Make the Tuplesortstate within the per-sort context. This way, we
* don't need a separate pfree() operation for it at shutdown.
*/
- oldcontext = MemoryContextSwitchTo(sortcontext);
+ oldcontext = MemoryContextSwitchTo(maincontext);
state = (Tuplesortstate *) palloc0(sizeof(Tuplesortstate));
@@ -740,6 +768,7 @@ tuplesort_begin_common(int workMem, SortCoordinate coordinate,
state->availMem = state->allowedMem;
state->sortcontext = sortcontext;
state->tuplecontext = tuplecontext;
+ state->maincontext = maincontext;
state->tapeset = NULL;
state->memtupcount = 0;
@@ -748,9 +777,7 @@ tuplesort_begin_common(int workMem, SortCoordinate coordinate,
* Initial size of array must be more than ALLOCSET_SEPARATE_THRESHOLD;
* see comments in grow_memtuples().
*/
- state->memtupsize = Max(1024,
- ALLOCSET_SEPARATE_THRESHOLD / sizeof(SortTuple) + 1);
-
+ state->memtupsize = INITIAL_MEMTUPSIZE;
state->growmemtuples = true;
state->slabAllocatorUsed = false;
state->memtuples = (SortTuple *) palloc(state->memtupsize * sizeof(SortTuple));
@@ -814,7 +841,7 @@ tuplesort_begin_heap(TupleDesc tupDesc,
MemoryContext oldcontext;
int i;
- oldcontext = MemoryContextSwitchTo(state->sortcontext);
+ oldcontext = MemoryContextSwitchTo(state->maincontext);
AssertArg(nkeys > 0);
@@ -890,7 +917,7 @@ tuplesort_begin_cluster(TupleDesc tupDesc,
Assert(indexRel->rd_rel->relam == BTREE_AM_OID);
- oldcontext = MemoryContextSwitchTo(state->sortcontext);
+ oldcontext = MemoryContextSwitchTo(state->maincontext);
#ifdef TRACE_SORT
if (trace_sort)
@@ -985,7 +1012,7 @@ tuplesort_begin_index_btree(Relation heapRel,
MemoryContext oldcontext;
int i;
- oldcontext = MemoryContextSwitchTo(state->sortcontext);
+ oldcontext = MemoryContextSwitchTo(state->maincontext);
#ifdef TRACE_SORT
if (trace_sort)
@@ -1064,7 +1091,7 @@ tuplesort_begin_index_hash(Relation heapRel,
randomAccess);
MemoryContext oldcontext;
- oldcontext = MemoryContextSwitchTo(state->sortcontext);
+ oldcontext = MemoryContextSwitchTo(state->maincontext);
#ifdef TRACE_SORT
if (trace_sort)
@@ -1107,7 +1134,7 @@ tuplesort_begin_datum(Oid datumType, Oid sortOperator, Oid sortCollation,
int16 typlen;
bool typbyval;
- oldcontext = MemoryContextSwitchTo(state->sortcontext);
+ oldcontext = MemoryContextSwitchTo(state->maincontext);
#ifdef TRACE_SORT
if (trace_sort)
@@ -1224,16 +1251,12 @@ tuplesort_set_bound(Tuplesortstate *state, int64 bound)
}
/*
- * tuplesort_end
- *
- * Release resources and clean up.
+ * tuplesort_free
*
- * NOTE: after calling this, any pointers returned by tuplesort_getXXX are
- * pointing to garbage. Be careful not to attempt to use or free such
- * pointers afterwards!
+ * Internal routine for freeing resources of tuplesort.
*/
-void
-tuplesort_end(Tuplesortstate *state)
+static void
+tuplesort_free(Tuplesortstate *state)
{
/* context swap probably not needed, but let's be safe */
MemoryContext oldcontext = MemoryContextSwitchTo(state->sortcontext);
@@ -1294,7 +1317,111 @@ tuplesort_end(Tuplesortstate *state)
* Free the per-sort memory context, thereby releasing all working memory,
* including the Tuplesortstate struct itself.
*/
- MemoryContextDelete(state->sortcontext);
+ MemoryContextReset(state->sortcontext);
+}
+
+/*
+ * tuplesort_end
+ *
+ * Release resources and clean up.
+ *
+ * NOTE: after calling this, any pointers returned by tuplesort_getXXX are
+ * pointing to garbage. Be careful not to attempt to use or free such
+ * pointers afterwards!
+ */
+void
+tuplesort_end(Tuplesortstate *state)
+{
+ tuplesort_free(state);
+ MemoryContextDelete(state->maincontext);
+}
+
+/*
+ * tuplesort_updatemax
+ *
+ * Update maximum resource usage statistics.
+ */
+static void
+tuplesort_updatemax(Tuplesortstate *state)
+{
+ int64 spaceUsed;
+ bool spaceUsedOnDisk;
+
+ /*
+ * Note: it might seem we should provide both memory and disk usage for a
+ * disk-based sort. However, the current code doesn't track memory space
+ * accurately once we have begun to return tuples to the caller (since we
+ * don't account for pfree's the caller is expected to do), so we cannot
+ * rely on availMem in a disk sort. This does not seem worth the overhead
+ * to fix. Is it worth creating an API for the memory context code to
+ * tell us how much is actually used in sortcontext?
+ */
+ if (state->tapeset)
+ {
+ spaceUsedOnDisk = true;
+ spaceUsed = LogicalTapeSetBlocks(state->tapeset) * BLCKSZ;
+ }
+ else
+ {
+ spaceUsedOnDisk = false;
+ spaceUsed = state->allowedMem - state->availMem;
+ }
+
+ /*
+ * Sort evicts data to the disk when it didn't manage to fit those data
+ * to the main memory. This is why we assume space used on the disk to
+ * be more important for tracking resource usage than space used in memory.
+ * Note that amount of space occupied by some tuple set on the disk might
+ * be less than amount of space occupied by the same tuple set in the
+ * memory due to more compact representation.
+ */
+ if ((spaceUsedOnDisk && !state->maxSpaceOnDisk) ||
+ (spaceUsedOnDisk == state->maxSpaceOnDisk && spaceUsed > state->maxSpace))
+ {
+ state->maxSpace = spaceUsed;
+ state->maxSpaceOnDisk = spaceUsedOnDisk;
+ state->maxSpaceStatus = state->status;
+ }
+}
+
+/*
+ * tuplesort_reset
+ *
+ * Reset the tuplesort. Reset all the data in the tuplesort, but leave the
+ * meta-information in. After tuplesort_reset, tuplesort is ready to start
+ * a new sort. It allows evade recreation of tuple sort (and save resources)
+ * when sorting multiple small batches.
+ */
+void
+tuplesort_reset(Tuplesortstate *state)
+{
+ tuplesort_updatemax(state);
+ tuplesort_free(state);
+
+ state->status = TSS_INITIAL;
+ state->memtupcount = 0;
+ state->boundUsed = false;
+ state->tapeset = NULL;
+ state->currentRun = 0;
+ state->result_tape = -1;
+ state->bounded = false;
+ state->availMem = state->allowedMem;
+ state->lastReturnedTuple = NULL;
+ state->slabAllocatorUsed = false;
+ state->slabMemoryBegin = NULL;
+ state->slabMemoryEnd = NULL;
+ state->slabFreeHead = NULL;
+ state->growmemtuples = true;
+
+ if (state->memtupsize < INITIAL_MEMTUPSIZE)
+ {
+ if (state->memtuples)
+ pfree(state->memtuples);
+ state->memtuples = (SortTuple *) palloc(INITIAL_MEMTUPSIZE * sizeof(SortTuple));
+ state->memtupsize = INITIAL_MEMTUPSIZE;
+ }
+
+ USEMEM(state, GetMemoryChunkSpace(state->memtuples));
}
/*
@@ -2591,8 +2718,7 @@ mergeruns(Tuplesortstate *state)
* Reset tuple memory. We've freed all the tuples that we previously
* allocated. We will use the slab allocator from now on.
*/
- MemoryContextDelete(state->tuplecontext);
- state->tuplecontext = NULL;
+ MemoryContextResetOnly(state->tuplecontext);
/*
* We no longer need a large memtuples array. (We will allocate a smaller
@@ -2642,7 +2768,8 @@ mergeruns(Tuplesortstate *state)
* from each input tape.
*/
state->memtupsize = numInputTapes;
- state->memtuples = (SortTuple *) palloc(numInputTapes * sizeof(SortTuple));
+ state->memtuples = (SortTuple *) MemoryContextAlloc(state->maincontext,
+ numInputTapes * sizeof(SortTuple));
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
/*
@@ -3139,18 +3266,15 @@ tuplesort_get_stats(Tuplesortstate *state,
* to fix. Is it worth creating an API for the memory context code to
* tell us how much is actually used in sortcontext?
*/
- if (state->tapeset)
- {
+ tuplesort_updatemax(state);
+
+ if (state->maxSpaceOnDisk)
stats->spaceType = SORT_SPACE_TYPE_DISK;
- stats->spaceUsed = LogicalTapeSetBlocks(state->tapeset) * (BLCKSZ / 1024);
- }
else
- {
stats->spaceType = SORT_SPACE_TYPE_MEMORY;
- stats->spaceUsed = (state->allowedMem - state->availMem + 1023) / 1024;
- }
+ stats->spaceUsed = (state->maxSpace + 1023) / 1024;
- switch (state->status)
+ switch (state->maxSpaceStatus)
{
case TSS_SORTEDINMEM:
if (state->boundUsed)
diff --git a/src/include/executor/nodeIncrementalSort.h b/src/include/executor/nodeIncrementalSort.h
new file mode 100644
index 0000000000..90d7a81711
--- /dev/null
+++ b/src/include/executor/nodeIncrementalSort.h
@@ -0,0 +1,30 @@
+/*-------------------------------------------------------------------------
+ *
+ * nodeIncrementalSort.h
+ *
+ *
+ *
+ * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/executor/nodeIncrementalSort.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef NODEINCREMENTALSORT_H
+#define NODEINCREMENTALSORT_H
+
+#include "access/parallel.h"
+#include "nodes/execnodes.h"
+
+extern IncrementalSortState *ExecInitIncrementalSort(IncrementalSort *node, EState *estate, int eflags);
+extern void ExecEndIncrementalSort(IncrementalSortState *node);
+extern void ExecReScanIncrementalSort(IncrementalSortState *node);
+
+/* parallel instrumentation support */
+extern void ExecIncrementalSortEstimate(IncrementalSortState *node, ParallelContext *pcxt);
+extern void ExecIncrementalSortInitializeDSM(IncrementalSortState *node, ParallelContext *pcxt);
+extern void ExecIncrementalSortInitializeWorker(IncrementalSortState *node, ParallelWorkerContext *pcxt);
+extern void ExecIncrementalSortRetrieveInstrumentation(IncrementalSortState *node);
+
+#endif /* NODEINCREMENTALSORT_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 538e679cdf..88f18e3701 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1876,6 +1876,20 @@ typedef struct MaterialState
Tuplestorestate *tuplestorestate;
} MaterialState;
+
+/* ----------------
+ * When performing sorting by multiple keys input dataset could be already
+ * presorted by some prefix of these keys. We call them "presorted keys".
+ * PresortedKeyData represents information about one such key.
+ * ----------------
+ */
+typedef struct PresortedKeyData
+{
+ FmgrInfo flinfo; /* comparison function info */
+ FunctionCallInfoData fcinfo; /* comparison function call info */
+ OffsetNumber attno; /* attribute number in tuple */
+} PresortedKeyData;
+
/* ----------------
* Shared memory container for per-worker sort information
* ----------------
@@ -1904,6 +1918,46 @@ typedef struct SortState
SharedSortInfo *shared_info; /* one entry per worker */
} SortState;
+/* ----------------
+ * Shared memory container for per-worker incremental sort information
+ * ----------------
+ */
+typedef struct IncrementalSortInfo
+{
+ TuplesortInstrumentation sinstrument;
+ int64 group_count;
+} IncrementalSortInfo;
+
+typedef struct SharedIncrementalSortInfo
+{
+ int num_workers;
+ IncrementalSortInfo sinfo[FLEXIBLE_ARRAY_MEMBER];
+} SharedIncrementalSortInfo;
+
+/* ----------------
+ * IncrementalSortState information
+ * ----------------
+ */
+typedef struct IncrementalSortState
+{
+ ScanState ss; /* its first field is NodeTag */
+ bool bounded; /* is the result set bounded? */
+ int64 bound; /* if bounded, how many tuples are needed */
+ bool sort_Done; /* sort completed yet? */
+ bool finished; /* fetching tuples from outer node
+ is finished ? */
+ bool bounded_Done; /* value of bounded we did the sort with */
+ int64 bound_Done; /* value of bound we did the sort with */
+ void *tuplesortstate; /* private state of tuplesort.c */
+ /* the keys by which the input path is already sorted */
+ PresortedKeyData *presorted_keys;
+ int64 group_count; /* number of groups with equal presorted keys */
+ /* slot for pivot tuple defining values of presorted keys within group */
+ TupleTableSlot *group_pivot;
+ bool am_worker; /* are we a worker? */
+ SharedIncrementalSortInfo *shared_info; /* one entry per worker */
+} IncrementalSortState;
+
/* ---------------------
* GroupState information
* ---------------------
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 4fc2de7184..cf9e2e64f9 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -74,6 +74,7 @@ typedef enum NodeTag
T_HashJoin,
T_Material,
T_Sort,
+ T_IncrementalSort,
T_Group,
T_Agg,
T_WindowAgg,
@@ -127,6 +128,7 @@ typedef enum NodeTag
T_HashJoinState,
T_MaterialState,
T_SortState,
+ T_IncrementalSortState,
T_GroupState,
T_AggState,
T_WindowAggState,
@@ -245,6 +247,7 @@ typedef enum NodeTag
T_ProjectionPath,
T_ProjectSetPath,
T_SortPath,
+ T_IncrementalSortPath,
T_GroupPath,
T_UpperUniquePath,
T_AggPath,
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 0a797f0a05..81f1844574 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -757,6 +757,17 @@ typedef struct Sort
bool *nullsFirst; /* NULLS FIRST/LAST directions */
} Sort;
+
+/* ----------------
+ * incremental sort node
+ * ----------------
+ */
+typedef struct IncrementalSort
+{
+ Sort sort;
+ int presortedCols; /* number of presorted columns */
+} IncrementalSort;
+
/* ---------------
* group node -
* Used for queries with GROUP BY (but no aggregates) specified.
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index acb8814924..75569203f3 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -1534,6 +1534,15 @@ typedef struct SortPath
Path *subpath; /* path representing input source */
} SortPath;
+/*
+ * IncrementalSortPath
+ */
+typedef struct IncrementalSortPath
+{
+ SortPath spath;
+ int presortedCols; /* number of presorted columns */
+} IncrementalSortPath;
+
/*
* GroupPath represents grouping (of presorted input)
*
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index d3269eae71..13b1c80632 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -61,6 +61,7 @@ extern PGDLLIMPORT bool enable_indexonlyscan;
extern PGDLLIMPORT bool enable_bitmapscan;
extern PGDLLIMPORT bool enable_tidscan;
extern PGDLLIMPORT bool enable_sort;
+extern PGDLLIMPORT bool enable_incrementalsort;
extern PGDLLIMPORT bool enable_hashagg;
extern PGDLLIMPORT bool enable_nestloop;
extern PGDLLIMPORT bool enable_material;
@@ -109,6 +110,15 @@ extern void cost_sort(Path *path, PlannerInfo *root,
List *pathkeys, Cost input_cost, double tuples, int width,
Cost comparison_cost, int sort_mem,
double limit_tuples);
+extern void cost_full_sort(Cost *startup_cost, Cost *run_cost,
+ Cost input_total_cost, double tuples, int width,
+ Cost comparison_cost, int sort_mem,
+ double limit_tuples);
+extern void cost_incremental_sort(Path *path,
+ PlannerInfo *root, List *pathkeys, int presorted_keys,
+ Cost input_startup_cost, Cost input_total_cost,
+ double input_tuples, int width, Cost comparison_cost, int sort_mem,
+ double limit_tuples);
extern void cost_append(AppendPath *path);
extern void cost_merge_append(Path *path, PlannerInfo *root,
List *pathkeys, int n_streams,
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index 895bf6959d..72da4cec08 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -170,6 +170,12 @@ extern ProjectSetPath *create_set_projection_path(PlannerInfo *root,
RelOptInfo *rel,
Path *subpath,
PathTarget *target);
+extern SortPath *create_incremental_sort_path(PlannerInfo *root,
+ RelOptInfo *rel,
+ Path *subpath,
+ List *pathkeys,
+ int presorted_keys,
+ double limit_tuples);
extern SortPath *create_sort_path(PlannerInfo *root,
RelOptInfo *rel,
Path *subpath,
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 50e180c554..3285a8055b 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -189,6 +189,8 @@ typedef enum
extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2);
extern bool pathkeys_contained_in(List *keys1, List *keys2);
+extern bool pathkeys_common_contained_in(List *keys1, List *keys2, int *n_common);
+extern int pathkeys_common(List *keys1, List *keys2);
extern Path *get_cheapest_path_for_pathkeys(List *paths, List *pathkeys,
Relids required_outer,
CostSelector cost_criterion,
diff --git a/src/include/utils/tuplesort.h b/src/include/utils/tuplesort.h
index d2e6754f04..4cad0d4fc2 100644
--- a/src/include/utils/tuplesort.h
+++ b/src/include/utils/tuplesort.h
@@ -192,8 +192,7 @@ extern Tuplesortstate *tuplesort_begin_heap(TupleDesc tupDesc,
int nkeys, AttrNumber *attNums,
Oid *sortOperators, Oid *sortCollations,
bool *nullsFirstFlags,
- int workMem, SortCoordinate coordinate,
- bool randomAccess);
+ int workMem, SortCoordinate coordinate, bool randomAccess);
extern Tuplesortstate *tuplesort_begin_cluster(TupleDesc tupDesc,
Relation indexRel, int workMem,
SortCoordinate coordinate, bool randomAccess);
@@ -240,6 +239,8 @@ extern bool tuplesort_skiptuples(Tuplesortstate *state, int64 ntuples,
extern void tuplesort_end(Tuplesortstate *state);
+extern void tuplesort_reset(Tuplesortstate *state);
+
extern void tuplesort_get_stats(Tuplesortstate *state,
TuplesortInstrumentation *stats);
extern const char *tuplesort_method_name(TuplesortMethod m);
diff --git a/src/test/isolation/expected/drop-index-concurrently-1.out b/src/test/isolation/expected/drop-index-concurrently-1.out
index 75dff56bc4..e11fb617b5 100644
--- a/src/test/isolation/expected/drop-index-concurrently-1.out
+++ b/src/test/isolation/expected/drop-index-concurrently-1.out
@@ -19,9 +19,10 @@ Sort
step explains: EXPLAIN (COSTS OFF) EXECUTE getrow_seq;
QUERY PLAN
-Sort
+Incremental Sort
Sort Key: id, data
- -> Seq Scan on test_dc
+ Presorted Key: id
+ -> Index Scan using test_dc_pkey on test_dc
Filter: ((data)::text = '34'::text)
step select2: SELECT * FROM test_dc WHERE data=34 ORDER BY id,data;
id data
diff --git a/src/test/regress/expected/incremental_sort.out b/src/test/regress/expected/incremental_sort.out
new file mode 100644
index 0000000000..fa7fb23319
--- /dev/null
+++ b/src/test/regress/expected/incremental_sort.out
@@ -0,0 +1,45 @@
+-- When we have to sort the entire table, incremental sort will
+-- be slower than plain sort, so it should not be used.
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten;
+ QUERY PLAN
+-----------------------------------
+ Sort
+ Sort Key: tenk1.four, tenk1.ten
+ -> Sort
+ Sort Key: tenk1.four
+ -> Seq Scan on tenk1
+(5 rows)
+
+-- When there is a LIMIT clause, incremental sort is beneficial because
+-- it only has to sort some of the groups, and not the entire table.
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten
+limit 1;
+ QUERY PLAN
+-----------------------------------------
+ Limit
+ -> Incremental Sort
+ Sort Key: tenk1.four, tenk1.ten
+ Presorted Key: tenk1.four
+ -> Sort
+ Sort Key: tenk1.four
+ -> Seq Scan on tenk1
+(7 rows)
+
+-- When work_mem is not enough to sort the entire table, incremental sort
+-- may be faster if individual groups still fit into work_mem.
+set work_mem to '2MB';
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten;
+ QUERY PLAN
+-----------------------------------
+ Incremental Sort
+ Sort Key: tenk1.four, tenk1.ten
+ Presorted Key: tenk1.four
+ -> Sort
+ Sort Key: tenk1.four
+ -> Seq Scan on tenk1
+(6 rows)
+
+reset work_mem;
diff --git a/src/test/regress/expected/partition_aggregate.out b/src/test/regress/expected/partition_aggregate.out
index 76a8209ec2..b7b65fc62d 100644
--- a/src/test/regress/expected/partition_aggregate.out
+++ b/src/test/regress/expected/partition_aggregate.out
@@ -8,6 +8,8 @@ SET enable_partitionwise_aggregate TO true;
SET enable_partitionwise_join TO true;
-- Disable parallel plans.
SET max_parallel_workers_per_gather TO 0;
+-- Disable incremental sort, which can influence selected plans due to fuzz factor.
+SET enable_incrementalsort TO off;
--
-- Tests for list partitioned tables.
--
diff --git a/src/test/regress/expected/sysviews.out b/src/test/regress/expected/sysviews.out
index a19ee08749..9dec75060d 100644
--- a/src/test/regress/expected/sysviews.out
+++ b/src/test/regress/expected/sysviews.out
@@ -76,6 +76,7 @@ select name, setting from pg_settings where name like 'enable%';
enable_gathermerge | on
enable_hashagg | on
enable_hashjoin | on
+ enable_incrementalsort | on
enable_indexonlyscan | on
enable_indexscan | on
enable_material | on
@@ -88,7 +89,7 @@ select name, setting from pg_settings where name like 'enable%';
enable_seqscan | on
enable_sort | on
enable_tidscan | on
-(16 rows)
+(17 rows)
-- Test that the pg_timezone_names and pg_timezone_abbrevs views are
-- more-or-less working. We can't test their contents in any great detail
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 00c324dd44..1e0d6f4b62 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -84,7 +84,7 @@ test: select_into select_distinct select_distinct_on select_implicit select_havi
# ----------
# Another group of parallel tests
# ----------
-test: brin gin gist spgist privileges init_privs security_label collate matview lock replica_identity rowsecurity object_address tablesample groupingsets drop_operator password func_index merge
+test: brin gin gist spgist privileges init_privs security_label collate matview lock replica_identity rowsecurity object_address tablesample groupingsets drop_operator password func_index merge incremental_sort
# ----------
# Another group of parallel tests
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 39c3fa9c85..c43abdf1fc 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -90,6 +90,7 @@ test: select_distinct_on
test: select_implicit
test: select_having
test: subselect
+test: incremental_sort
test: union
test: case
test: join
diff --git a/src/test/regress/sql/incremental_sort.sql b/src/test/regress/sql/incremental_sort.sql
new file mode 100644
index 0000000000..bd66228ada
--- /dev/null
+++ b/src/test/regress/sql/incremental_sort.sql
@@ -0,0 +1,18 @@
+-- When we have to sort the entire table, incremental sort will
+-- be slower than plain sort, so it should not be used.
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten;
+
+-- When there is a LIMIT clause, incremental sort is beneficial because
+-- it only has to sort some of the groups, and not the entire table.
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten
+limit 1;
+
+-- When work_mem is not enough to sort the entire table, incremental sort
+-- may be faster if individual groups still fit into work_mem.
+set work_mem to '2MB';
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten;
+reset work_mem;
+
diff --git a/src/test/regress/sql/partition_aggregate.sql b/src/test/regress/sql/partition_aggregate.sql
index c60d7d2342..1b05456316 100644
--- a/src/test/regress/sql/partition_aggregate.sql
+++ b/src/test/regress/sql/partition_aggregate.sql
@@ -9,6 +9,8 @@ SET enable_partitionwise_aggregate TO true;
SET enable_partitionwise_join TO true;
-- Disable parallel plans.
SET max_parallel_workers_per_gather TO 0;
+-- Disable incremental sort, which can influence selected plans due to fuzz factor.
+SET enable_incrementalsort TO off;
--
-- Tests for list partitioned tables.