surjective-index.patch

diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 6d1f22f..37fc407 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -130,6 +130,15 @@ static relopt_bool boolRelOpts[] =
 	},
 	{
 		{
+			"surjective",
+			"Reevaluate functional index expression on update to check if its values is changed",
+			RELOPT_KIND_INDEX,
+			AccessExclusiveLock
+		},
+		true
+	},
+	{
+		{
 			"security_barrier",
 			"View acts as a row security barrier",
 			RELOPT_KIND_VIEW,
@@ -1301,7 +1310,7 @@ fillRelOptions(void *rdopts, Size basesize,
 				break;
 			}
 		}
-		if (validate && !found)
+		if (validate && !found && options[i].gen->kinds != RELOPT_KIND_INDEX)
 			elog(ERROR, "reloption \"%s\" not found in parse table",
 				 options[i].gen->name);
 	}
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index e890e08..3525e3c 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -56,6 +56,7 @@
 #include "access/xlogutils.h"
 #include "catalog/catalog.h"
 #include "catalog/namespace.h"
+#include "catalog/index.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "storage/bufmgr.h"
@@ -73,7 +74,9 @@
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
 #include "utils/tqual.h"
-
+#include "utils/memutils.h"
+#include "nodes/execnodes.h"
+#include "executor/executor.h"
 
 /* GUC variable */
 bool		synchronize_seqscans = true;
@@ -4199,6 +4202,7 @@ l2:
 
 	if (use_hot_update)
 	{
+		elog(DEBUG1, "Use hot update");
 		/* Mark the old tuple as HOT-updated */
 		HeapTupleSetHotUpdated(&oldtup);
 		/* And mark the new tuple as heap-only */
@@ -4436,6 +4440,73 @@ HeapDetermineModifiedColumns(Relation relation, Bitmapset *interesting_cols,
 								attnum - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	if (hot_result && relation->rd_surjective)
+	{
+		ListCell       *l;
+		List	       *indexoidlist = RelationGetIndexList(relation);
+		EState         *estate = CreateExecutorState();
+		ExprContext    *econtext = GetPerTupleExprContext(estate);
+		TupleTableSlot *slot = MakeSingleTupleTableSlot(RelationGetDescr(relation));
+		Datum	   	    old_values[INDEX_MAX_KEYS];
+		bool		    old_isnull[INDEX_MAX_KEYS];
+		Datum	   	    new_values[INDEX_MAX_KEYS];
+		bool		    new_isnull[INDEX_MAX_KEYS];
+
+		econtext->ecxt_scantuple = slot;
+
+		foreach(l, indexoidlist)
+		{
+			Oid		    indexOid = lfirst_oid(l);
+			Relation    indexDesc = index_open(indexOid, AccessShareLock);
+			IndexInfo  *indexInfo = BuildIndexInfo(indexDesc);
+			int         i;
+
+			if (indexInfo->ii_Expressions && indexInfo->ii_Surjective)
+			{
+				ResetExprContext(econtext);
+				ExecStoreTuple(oldtup, slot, InvalidBuffer, false);
+				FormIndexDatum(indexInfo,
+							   slot,
+							   estate,
+							   old_values,
+							   old_isnull);
+
+				ExecStoreTuple(newtup, slot, InvalidBuffer, false);
+				FormIndexDatum(indexInfo,
+							   slot,
+							   estate,
+							   new_values,
+							   new_isnull);
+
+				for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
+				{
+					if (old_isnull[i] != new_isnull[i])
+					{
+						hot_result = false;
+						break;
+					}
+					else if (!old_isnull[i])
+					{
+						Form_pg_attribute att = RelationGetDescr(indexDesc)->attrs[i];
+						if (!datumIsEqual(old_values[i], new_values[i], att->attbyval, att->attlen))
+						{
+							hot_result = false;
+							break;
+						}
+
+					}
+				}
+			}
+			index_close(indexDesc, AccessShareLock);
+		}
+		ExecDropSingleTupleTableSlot(slot);
+		FreeExecutorState(estate);
+	}
+
+	*satisfies_hot = hot_result;
+	*satisfies_key = key_result;
+	*satisfies_id = id_result;
+
 	return modified;
 }
 
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 2328b92..91217fa 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -26,6 +26,7 @@
 #include "access/amapi.h"
 #include "access/multixact.h"
 #include "access/relscan.h"
+#include "access/reloptions.h"
 #include "access/sysattr.h"
 #include "access/transam.h"
 #include "access/visibilitymap.h"
@@ -86,6 +87,13 @@ typedef struct
 				tups_inserted;
 } v_i_state;
 
+/* options common to all indexes */
+typedef struct
+{
+	int32		vl_len_;
+	bool        surjective;
+} index_options;
+
 /* non-export function prototypes */
 static bool relationHasPrimaryKey(Relation rel);
 static TupleDesc ConstructTupleDescriptor(Relation heapRelation,
@@ -1676,6 +1684,40 @@ BuildIndexInfo(Relation index)
 		ii->ii_ExclusionStrats = NULL;
 	}
 
+	if (ii->ii_Expressions)
+	{
+		HeapTuple       tuple;
+		Datum           reloptions;
+		bool            isnull;
+
+		ii->ii_Surjective = true; /* by default functional index is considered as surjective */
+
+		tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(RelationGetRelid(index)));
+		if (!HeapTupleIsValid(tuple))
+			elog(ERROR, "cache lookup failed for relation %u", RelationGetRelid(index));
+
+		reloptions = SysCacheGetAttr(RELOID, tuple,
+									 Anum_pg_class_reloptions, &isnull);
+		if (!isnull)
+		{
+			static const relopt_parse_elt tab[] = {
+				{"surjective", RELOPT_TYPE_BOOL, offsetof(index_options, surjective)}
+			};
+			int                       numoptions;
+			relopt_value *options = parseRelOptions(reloptions, false,
+													RELOPT_KIND_INDEX,
+													&numoptions);
+			if (numoptions != 0)
+			{
+				index_options optstruct;
+				fillRelOptions((void *)&optstruct, sizeof(bool), options, numoptions, false, tab, lengthof(tab));
+				ii->ii_Surjective = optstruct.surjective;
+				pfree(options);
+			}
+		}
+		ReleaseSysCache(tuple);
+	}
+
 	/* other info */
 	ii->ii_Unique = indexStruct->indisunique;
 	ii->ii_ReadyForInserts = IndexIsReady(indexStruct);
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index c2e8361..d3b75f6 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -4854,6 +4854,7 @@ RelationGetIndexAttrBitmap(Relation relation, IndexAttrBitmapKind attrKind)
 	List	   *newindexoidlist;
 	Oid			relpkindex;
 	Oid			relreplindex;
+	bool        surjective = false;
 	ListCell   *l;
 	MemoryContext oldcxt;
 
@@ -4963,9 +4964,15 @@ restart:
 			}
 		}
 
-		/* Collect all attributes used in expressions, too */
-		pull_varattnos((Node *) indexInfo->ii_Expressions, 1, &indexattrs);
-
+		if (indexInfo->ii_Expressions && indexInfo->ii_Surjective)
+		{
+			surjective = true;
+		}
+		else
+		{
+			/* Collect all attributes used in expressions, too */
+			pull_varattnos((Node *) indexInfo->ii_Expressions, 1, &indexattrs);
+		}
 		/* Collect all attributes in the index predicate, too */
 		pull_varattnos((Node *) indexInfo->ii_Predicate, 1, &indexattrs);
 
@@ -5010,6 +5017,8 @@ restart:
 	bms_free(relation->rd_idattr);
 	relation->rd_idattr = NULL;
 
+	relation->rd_surjective = surjective;
+
 	/*
 	 * Now save copies of the bitmaps in the relcache entry.  We intentionally
 	 * set rd_indexattr last, because that's the one that signals validity of
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 2abd087..f404888 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -1647,11 +1647,11 @@ psql_completion(const char *text, int start, int end)
 		COMPLETE_WITH_CONST("(");
 	/* ALTER INDEX <foo> SET|RESET ( */
 	else if (Matches5("ALTER", "INDEX", MatchAny, "RESET", "("))
-		COMPLETE_WITH_LIST3("fillfactor", "fastupdate",
-							"gin_pending_list_limit");
+		COMPLETE_WITH_LIST4("fillfactor", "fastupdate",
+							"gin_pending_list_limit", "surjective");
 	else if (Matches5("ALTER", "INDEX", MatchAny, "SET", "("))
-		COMPLETE_WITH_LIST3("fillfactor =", "fastupdate =",
-							"gin_pending_list_limit =");
+		COMPLETE_WITH_LIST4("fillfactor =", "fastupdate =",
+							"gin_pending_list_limit =", "surjective = ");
 
 	/* ALTER LANGUAGE <name> */
 	else if (Matches3("ALTER", "LANGUAGE", MatchAny))
diff --git a/src/include/access/reloptions.h b/src/include/access/reloptions.h
index 91b2cd7..1fba0f0 100644
--- a/src/include/access/reloptions.h
+++ b/src/include/access/reloptions.h
@@ -51,6 +51,7 @@ typedef enum relopt_kind
 	RELOPT_KIND_PARTITIONED = (1 << 11),
 	/* if you add a new kind, make sure you update "last_default" too */
 	RELOPT_KIND_LAST_DEFAULT = RELOPT_KIND_PARTITIONED,
+	RELOPT_KIND_INDEX = RELOPT_KIND_BTREE|RELOPT_KIND_HASH|RELOPT_KIND_GIN|RELOPT_KIND_SPGIST,
 	/* some compilers treat enums as signed ints, so we can't use 1 << 31 */
 	RELOPT_KIND_MAX = (1 << 30)
 } relopt_kind;
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index d33392f..f67c9f0 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -147,6 +147,7 @@ typedef struct IndexInfo
 	bool		ii_ReadyForInserts;
 	bool		ii_Concurrent;
 	bool		ii_BrokenHotChain;
+	bool        ii_Surjective;
 	void	   *ii_AmCache;
 	MemoryContext ii_Context;
 } IndexInfo;
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 8476896..147ba89 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -125,6 +125,8 @@ typedef struct RelationData
 	List	   *rd_fkeylist;	/* list of ForeignKeyCacheInfo (see below) */
 	bool		rd_fkeyvalid;	/* true if list has been computed */
 
+	bool        rd_surjective;   /* relation contains functional index with surjective function */
+
 	MemoryContext rd_partkeycxt;	/* private memory cxt for the below */
 	struct PartitionKeyData *rd_partkey;		/* partition key, or NULL */
 	MemoryContext rd_pdcxt;		/* private context for partdesc */
diff --git a/src/test/regress/expected/func_index.out b/src/test/regress/expected/func_index.out
new file mode 100644
index 0000000..c57a46a
--- /dev/null
+++ b/src/test/regress/expected/func_index.out
@@ -0,0 +1,29 @@
+create table keyvalue(id integer primary key, info jsonb);
+create index nameindex on keyvalue((info->>'name')) with (surjective=false);
+set client_min_messages=debug1;
+insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
+update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
+set client_min_messages=notice;
+drop table keyvalue;
+create table keyvalue(id integer primary key, info jsonb);
+create index nameindex on keyvalue((info->>'name')) with (surjective=true);
+set client_min_messages=debug1;
+insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
+update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
+DEBUG:  Use hot update
+update keyvalue set info='{"name": "smith", "data": "some other data"}' where id=1;
+update keyvalue set info='{"name": "smith", "data": "some more data"}' where id=1;
+DEBUG:  Use hot update
+set client_min_messages=notice;
+drop table keyvalue;
+create table keyvalue(id integer primary key, info jsonb);
+create index nameindex on keyvalue((info->>'name'));
+set client_min_messages=debug1;
+insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
+update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
+DEBUG:  Use hot update
+update keyvalue set info='{"name": "smith", "data": "some other data"}' where id=1;
+update keyvalue set info='{"name": "smith", "data": "some more data"}' where id=1;
+DEBUG:  Use hot update
+set client_min_messages=notice;
+drop table keyvalue;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 1f8f098..06fd9aa 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -79,7 +79,7 @@ ignore: random
 # ----------
 # Another group of parallel tests
 # ----------
-test: select_into select_distinct select_distinct_on select_implicit select_having subselect union case join aggregates transactions random portals arrays btree_index hash_index update namespace prepared_xacts delete
+test: select_into select_distinct select_distinct_on select_implicit select_having subselect union case join aggregates transactions random portals arrays btree_index hash_index func_index update namespace prepared_xacts delete
 
 # ----------
 # Another group of parallel tests
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 04206c3..4f8b460 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -98,6 +98,7 @@ test: portals
 test: arrays
 test: btree_index
 test: hash_index
+test: func_index
 test: update
 test: delete
 test: namespace
diff --git a/src/test/regress/sql/func_index.sql b/src/test/regress/sql/func_index.sql
new file mode 100644
index 0000000..4923382
--- /dev/null
+++ b/src/test/regress/sql/func_index.sql
@@ -0,0 +1,29 @@
+create table keyvalue(id integer primary key, info jsonb);
+create index nameindex on keyvalue((info->>'name')) with (surjective=false);
+set client_min_messages=debug1;
+insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
+update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
+set client_min_messages=notice;
+drop table keyvalue;
+
+create table keyvalue(id integer primary key, info jsonb);
+create index nameindex on keyvalue((info->>'name')) with (surjective=true);
+set client_min_messages=debug1;
+insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
+update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
+update keyvalue set info='{"name": "smith", "data": "some other data"}' where id=1;
+update keyvalue set info='{"name": "smith", "data": "some more data"}' where id=1;
+set client_min_messages=notice;
+drop table keyvalue;
+
+create table keyvalue(id integer primary key, info jsonb);
+create index nameindex on keyvalue((info->>'name'));
+set client_min_messages=debug1;
+insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
+update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
+update keyvalue set info='{"name": "smith", "data": "some other data"}' where id=1;
+update keyvalue set info='{"name": "smith", "data": "some more data"}' where id=1;
+set client_min_messages=notice;
+drop table keyvalue;
+
+