extstats_pg_dump_and_comment_support.patch

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 40af053..1e42f05 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -16418,6 +16418,10 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
    </indexterm>
 
    <indexterm>
+    <primary>pg_get_statisticsextdef</primary>
+   </indexterm>
+
+   <indexterm>
     <primary>pg_get_triggerdef</primary>
    </indexterm>
 
@@ -16587,6 +16591,11 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
        uses</entry>
       </row>
       <row>
+       <entry><literal><function>pg_get_statisticsextdef(<parameter>statext_oid</parameter>)</function></literal></entry>
+       <entry><type>text</type></entry>
+       <entry>get <command>CREATE STATISTICS</> command for extended statistics objects</entry>
+      </row>
+      <row>
        <entry><function>pg_get_triggerdef</function>(<parameter>trigger_oid</parameter>)</entry>
        <entry><type>text</type></entry>
        <entry>get <command>CREATE [ CONSTRAINT ] TRIGGER</> command for trigger</entry>
@@ -16730,20 +16739,22 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
 
   <para>
    <function>pg_get_constraintdef</function>,
-   <function>pg_get_indexdef</function>, <function>pg_get_ruledef</function>,
-   and <function>pg_get_triggerdef</function>, respectively reconstruct the
-   creating command for a constraint, index, rule, or trigger. (Note that this
-   is a decompiled reconstruction, not the original text of the command.)
-   <function>pg_get_expr</function> decompiles the internal form of an
-   individual expression, such as the default value for a column.  It can be
-   useful when examining the contents of system catalogs.  If the expression
-   might contain Vars, specify the OID of the relation they refer to as the
-   second parameter; if no Vars are expected, zero is sufficient.
-   <function>pg_get_viewdef</function> reconstructs the <command>SELECT</>
-   query that defines a view. Most of these functions come in two variants,
-   one of which can optionally <quote>pretty-print</> the result.  The
-   pretty-printed format is more readable, but the default format is more
-   likely to be interpreted the same way by future versions of
+   <function>pg_get_indexdef</function>,
+   <function>pg_get_statisticsextdef</function>,
+   <function>pg_get_ruledef</function>, and
+   <function>pg_get_triggerdef</function>, respectively reconstruct the
+   creating command for a constraint, index, extended statistics object, rule,
+   or trigger. (Note that this is a decompiled reconstruction, not the
+   original text of the command.) <function>pg_get_expr</function> decompiles
+   the internal form of an individual expression, such as the default value
+   for a column.  It can be useful when examining the contents of system
+   catalogs.  If the expression might contain Vars, specify the OID of the
+   relation they refer to as the second parameter; if no Vars are expected,
+   zero is sufficient. <function>pg_get_viewdef</function> reconstructs the
+   <command>SELECT</> query that defines a view. Most of these functions come
+   in two variants, one of which can optionally <quote>pretty-print</> the
+   result.  The pretty-printed format is more readable, but the default format
+   is more likely to be interpreted the same way by future versions of
    <productname>PostgreSQL</>; avoid using pretty-printed output for dump
    purposes.  Passing <literal>false</> for the pretty-print parameter yields
    the same result as the variant that does not have the parameter at all.
diff --git a/doc/src/sgml/ref/comment.sgml b/doc/src/sgml/ref/comment.sgml
index c1cf587..d94bc85 100644
--- a/doc/src/sgml/ref/comment.sgml
+++ b/doc/src/sgml/ref/comment.sgml
@@ -51,6 +51,7 @@ COMMENT ON
   SCHEMA <replaceable class="PARAMETER">object_name</replaceable> |
   SEQUENCE <replaceable class="PARAMETER">object_name</replaceable> |
   SERVER <replaceable class="PARAMETER">object_name</replaceable> |
+  STATISTICS <replaceable class="PARAMETER">object_name</replaceable> |
   TABLE <replaceable class="PARAMETER">object_name</replaceable> |
   TABLESPACE <replaceable class="PARAMETER">object_name</replaceable> |
   TEXT SEARCH CONFIGURATION <replaceable class="PARAMETER">object_name</replaceable> |
@@ -125,8 +126,8 @@ COMMENT ON
       The name of the object to be commented.  Names of tables,
       aggregates, collations, conversions, domains, foreign tables, functions,
       indexes, operators, operator classes, operator families, sequences,
-      text search objects, types, and views can be schema-qualified.
-      When commenting on a column,
+      statistics, text search objects, types, and views can be
+      schema-qualified. When commenting on a column,
       <replaceable class="parameter">relation_name</replaceable> must refer
       to a table, view, composite type, or foreign table.
      </para>
@@ -327,6 +328,7 @@ COMMENT ON RULE my_rule ON my_table IS 'Logs updates of employee records';
 COMMENT ON SCHEMA my_schema IS 'Departmental data';
 COMMENT ON SEQUENCE my_sequence IS 'Used to generate primary keys';
 COMMENT ON SERVER myserver IS 'my foreign server';
+COMMENT ON STATISTICS my_statistics IS 'Improves planner row estimations';
 COMMENT ON TABLE my_schema.my_table IS 'Employee Information';
 COMMENT ON TABLESPACE my_tablespace IS 'Tablespace for indexes';
 COMMENT ON TEXT SEARCH CONFIGURATION my_config IS 'Special word filtering';
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index a755646..2ca8e75 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -6197,7 +6197,7 @@ opt_restart_seqs:
  *                 EXTENSION | EVENT TRIGGER | FOREIGN DATA WRAPPER |
  *                 FOREIGN TABLE | INDEX | [PROCEDURAL] LANGUAGE |
  *                 MATERIALIZED VIEW | POLICY | ROLE | SCHEMA | SEQUENCE |
- *                 SERVER | TABLE | TABLESPACE |
+ *                 SERVER | STATISTICS | TABLE | TABLESPACE |
  *                 TEXT SEARCH CONFIGURATION | TEXT SEARCH DICTIONARY |
  *                 TEXT SEARCH PARSER | TEXT SEARCH TEMPLATE | TYPE |
  *                 VIEW] <objname> |
@@ -6384,6 +6384,7 @@ comment_type:
 			| SCHEMA							{ $$ = OBJECT_SCHEMA; }
 			| INDEX								{ $$ = OBJECT_INDEX; }
 			| SEQUENCE							{ $$ = OBJECT_SEQUENCE; }
+			| STATISTICS						{ $$ = OBJECT_STATISTICS; }
 			| TABLE								{ $$ = OBJECT_TABLE; }
 			| VIEW								{ $$ = OBJECT_VIEW; }
 			| MATERIALIZED VIEW					{ $$ = OBJECT_MATVIEW; }
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index b27b77d..680aef9 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -35,6 +35,7 @@
 #include "catalog/pg_operator.h"
 #include "catalog/pg_partitioned_table.h"
 #include "catalog/pg_proc.h"
+#include "catalog/pg_statistic_ext.h"
 #include "catalog/pg_trigger.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
@@ -317,6 +318,7 @@ static char *pg_get_indexdef_worker(Oid indexrelid, int colno,
 					   const Oid *excludeOps,
 					   bool attrsOnly, bool showTblSpc,
 					   int prettyFlags, bool missing_ok);
+static char *pg_get_statisticsext_worker(Oid statextid, bool missing_ok);
 static char *pg_get_partkeydef_worker(Oid relid, int prettyFlags);
 static char *pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
 							int prettyFlags, bool missing_ok);
@@ -1419,6 +1421,85 @@ pg_get_indexdef_worker(Oid indexrelid, int colno,
 }
 
 /*
+ * pg_get_statisticsextdef
+ *		Get the definition of an extended statistics object
+ */
+Datum
+pg_get_statisticsextdef(PG_FUNCTION_ARGS)
+{
+	Oid			statextid = PG_GETARG_OID(0);
+	char	   *res;
+
+	res = pg_get_statisticsext_worker(statextid, true);
+
+	if (res == NULL)
+		PG_RETURN_NULL();
+
+	PG_RETURN_TEXT_P(string_to_text(res));
+}
+
+/*
+ * Internal workhorse to decompile an extended statistics object.
+ */
+static char *
+pg_get_statisticsext_worker(Oid statextid, bool missing_ok)
+{
+	Form_pg_statistic_ext	statextrec;
+	Form_pg_class			pgclassrec;
+	HeapTuple	statexttup;
+	HeapTuple	pgclasstup;
+	StringInfoData buf;
+	int			colno;
+
+	statexttup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(statextid));
+
+	if (!HeapTupleIsValid(statexttup))
+	{
+		if (missing_ok)
+			return NULL;
+		elog(ERROR, "cache lookup failed for extended statistics %u", statextid);
+	}
+
+	statextrec = (Form_pg_statistic_ext) GETSTRUCT(statexttup);
+
+	pgclasstup = SearchSysCache1(RELOID, ObjectIdGetDatum(statextrec->starelid));
+
+	if (!HeapTupleIsValid(statexttup))
+	{
+		ReleaseSysCache(statexttup);
+		elog(ERROR, "cache lookup failed for relation %u", statextrec->starelid);
+	}
+
+	pgclassrec = (Form_pg_class) GETSTRUCT(pgclasstup);
+
+	initStringInfo(&buf);
+
+	appendStringInfo(&buf, "CREATE STATISTICS %s ON (",
+							quote_identifier(NameStr(statextrec->staname)));
+
+	for (colno = 0; colno < statextrec->stakeys.dim1; colno++)
+	{
+		AttrNumber	attnum = statextrec->stakeys.values[colno];
+		char	   *attname;
+
+		if (colno > 0)
+			appendStringInfoString(&buf, ", ");
+
+		attname = get_relid_attribute_name(statextrec->starelid, attnum);
+
+		appendStringInfoString(&buf, attname);
+	}
+
+	appendStringInfo(&buf, ") FROM %s",
+							quote_identifier(NameStr(pgclassrec->relname)));
+
+	ReleaseSysCache(statexttup);
+	ReleaseSysCache(pgclasstup);
+
+	return buf.data;
+}
+
+/*
  * pg_get_partkeydef
  *
  * Returns the partition key specification, ie, the following:
diff --git a/src/bin/pg_dump/common.c b/src/bin/pg_dump/common.c
index 89530a9..e2bc357 100644
--- a/src/bin/pg_dump/common.c
+++ b/src/bin/pg_dump/common.c
@@ -273,6 +273,10 @@ getSchemaData(Archive *fout, int *numTablesPtr)
 	getIndexes(fout, tblinfo, numTables);
 
 	if (g_verbose)
+		write_msg(NULL, "reading extended statistics\n");
+	getExtendedStatistics(fout, tblinfo, numTables);
+
+	if (g_verbose)
 		write_msg(NULL, "reading constraints\n");
 	getConstraints(fout, tblinfo, numTables);
 
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 7273ec8..0ab2cc6 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -190,6 +190,7 @@ static void dumpAttrDef(Archive *fout, AttrDefInfo *adinfo);
 static void dumpSequence(Archive *fout, TableInfo *tbinfo);
 static void dumpSequenceData(Archive *fout, TableDataInfo *tdinfo);
 static void dumpIndex(Archive *fout, IndxInfo *indxinfo);
+static void dumpStatisticsExt(Archive *fout, StatsExtInfo *statsextinfo);
 static void dumpConstraint(Archive *fout, ConstraintInfo *coninfo);
 static void dumpTableConstraintComment(Archive *fout, ConstraintInfo *coninfo);
 static void dumpTSParser(Archive *fout, TSParserInfo *prsinfo);
@@ -6507,6 +6508,100 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 }
 
 /*
+ * getExtendedStatistics
+ *	  get information about extended statistics on a dumpable table
+ *	  or materialized view.
+ *
+ * Note: extended statistics data is not returned directly to the caller, but
+ * it does get entered into the DumpableObject tables.
+ */
+void
+getExtendedStatistics(Archive *fout, TableInfo tblinfo[], int numTables)
+{
+	int				i,
+					j;
+	PQExpBuffer		query;
+	PGresult	   *res;
+	StatsExtInfo   *statsextinfo;
+	int				ntups;
+	int				i_tableoid;
+	int				i_oid;
+	int				i_staname;
+	int				i_stadef;
+
+	/* Extended statistics were new in v10 */
+	if (fout->remoteVersion < 100000)
+		return;
+
+	query = createPQExpBuffer();
+
+	for (i = 0; i < numTables; i++)
+	{
+		TableInfo  *tbinfo = &tblinfo[i];
+
+		/* Only plain tables and materialized views can have extended statistics. */
+		/* XXX ensure this is true. It was broken in v25 0002 */
+		if (tbinfo->relkind != RELKIND_RELATION &&
+			tbinfo->relkind != RELKIND_MATVIEW)
+			continue;
+
+		/*
+		 * Ignore extended statistics of tables whose definitions are not to
+		 * be dumped.
+		 */
+		if (!(tbinfo->dobj.dump & DUMP_COMPONENT_DEFINITION))
+			continue;
+
+		if (g_verbose)
+			write_msg(NULL, "reading extended statistics for table \"%s.%s\"\n",
+					  tbinfo->dobj.namespace->dobj.name,
+					  tbinfo->dobj.name);
+
+		/* Make sure we are in proper schema so stadef is right */
+		selectSourceSchema(fout, tbinfo->dobj.namespace->dobj.name);
+
+		resetPQExpBuffer(query);
+
+		appendPQExpBuffer(query,
+						  "SELECT "
+							"tableoid, "
+							"oid, "
+							"staname, "
+						  "pg_catalog.pg_get_statisticsextdef(oid) AS stadef "
+						  "FROM pg_statistic_ext "
+						  "WHERE starelid = '%u' "
+						  "ORDER BY staname", tbinfo->dobj.catId.oid);
+
+		res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
+
+		ntups = PQntuples(res);
+
+		i_tableoid = PQfnumber(res, "tableoid");
+		i_oid = PQfnumber(res, "oid");
+		i_staname = PQfnumber(res, "staname");
+		i_stadef = PQfnumber(res, "stadef");
+
+		statsextinfo = (StatsExtInfo *) pg_malloc(ntups * sizeof(StatsExtInfo));
+
+		for (j = 0; j < ntups; j++)
+		{
+			statsextinfo[j].dobj.objType = DO_STATSEXT;
+			statsextinfo[j].dobj.catId.tableoid = atooid(PQgetvalue(res, j, i_tableoid));
+			statsextinfo[j].dobj.catId.oid = atooid(PQgetvalue(res, j, i_oid));
+			AssignDumpId(&statsextinfo[j].dobj);
+			statsextinfo[j].dobj.name = pg_strdup(PQgetvalue(res, j, i_staname));
+			statsextinfo[j].dobj.namespace = tbinfo->dobj.namespace;
+			statsextinfo[j].statsexttable = tbinfo;
+			statsextinfo[j].statsextdef = pg_strdup(PQgetvalue(res, j, i_stadef));
+		}
+
+		PQclear(res);
+	}
+
+	destroyPQExpBuffer(query);
+}
+
+/*
  * getConstraints
  *
  * Get info about constraints on dumpable tables.
@@ -9157,6 +9252,9 @@ dumpDumpableObject(Archive *fout, DumpableObject *dobj)
 		case DO_INDEX:
 			dumpIndex(fout, (IndxInfo *) dobj);
 			break;
+		case DO_STATSEXT:
+			dumpStatisticsExt(fout, (StatsExtInfo *) dobj);
+			break;
 		case DO_REFRESH_MATVIEW:
 			refreshMatViewData(fout, (TableDataInfo *) dobj);
 			break;
@@ -15596,6 +15694,61 @@ dumpIndex(Archive *fout, IndxInfo *indxinfo)
 }
 
 /*
+ * dumpStatisticsExt
+ *	  write out to fout an extended statistics object
+ */
+static void
+dumpStatisticsExt(Archive *fout, StatsExtInfo *statsextinfo)
+{
+	DumpOptions *dopt = fout->dopt;
+	TableInfo  *tbinfo = statsextinfo->statsexttable;
+	PQExpBuffer q;
+	PQExpBuffer delq;
+	PQExpBuffer labelq;
+
+	if (dopt->dataOnly)
+		return;
+
+	q = createPQExpBuffer();
+	delq = createPQExpBuffer();
+	labelq = createPQExpBuffer();
+
+	appendPQExpBuffer(labelq, "STATISTICS %s",
+					  fmtId(statsextinfo->dobj.name));
+
+	appendPQExpBuffer(q, "%s;\n", statsextinfo->statsextdef);
+
+	appendPQExpBuffer(delq, "DROP STATISTICS %s.",
+						  fmtId(tbinfo->dobj.namespace->dobj.name));
+	appendPQExpBuffer(delq, "%s;\n",
+						  fmtId(statsextinfo->dobj.name));
+
+	if (statsextinfo->dobj.dump & DUMP_COMPONENT_DEFINITION)
+			ArchiveEntry(fout, statsextinfo->dobj.catId,
+						 statsextinfo->dobj.dumpId,
+						 statsextinfo->dobj.name,
+						 tbinfo->dobj.namespace->dobj.name,
+						 NULL,
+						 tbinfo->rolname, false,
+						 "STATISTICS", SECTION_POST_DATA,
+						 q->data, delq->data, NULL,
+						 NULL, 0,
+						 NULL, NULL);
+
+	/* Dump Statistics Comments */
+	if (statsextinfo->dobj.dump & DUMP_COMPONENT_COMMENT)
+		dumpComment(fout, labelq->data,
+					tbinfo->dobj.namespace->dobj.name,
+					tbinfo->rolname,
+					statsextinfo->dobj.catId, 0,
+					statsextinfo->dobj.dumpId);
+
+	destroyPQExpBuffer(q);
+	destroyPQExpBuffer(delq);
+	destroyPQExpBuffer(labelq);
+}
+
+/*
  * dumpConstraint
  *	  write out to fout a user-defined constraint
  */
@@ -17133,6 +17286,7 @@ addBoundaryDependencies(DumpableObject **dobjs, int numObjs,
 				addObjectDependency(postDataBound, dobj->dumpId);
 				break;
 			case DO_INDEX:
+			case DO_STATSEXT:
 			case DO_REFRESH_MATVIEW:
 			case DO_TRIGGER:
 			case DO_EVENT_TRIGGER:
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index a466527..cb22f63 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -56,6 +56,7 @@ typedef enum
 	DO_TABLE,
 	DO_ATTRDEF,
 	DO_INDEX,
+	DO_STATSEXT,
 	DO_RULE,
 	DO_TRIGGER,
 	DO_CONSTRAINT,
@@ -362,6 +363,13 @@ typedef struct _indxInfo
 	int			relpages;		/* relpages of the underlying table */
 } IndxInfo;
 
+typedef struct _statsExtInfo
+{
+	DumpableObject dobj;
+	TableInfo  *statsexttable;	/* link to table the stats ext is for */
+	char	   *statsextdef;
+} StatsExtInfo;
+
 typedef struct _ruleInfo
 {
 	DumpableObject dobj;
@@ -682,6 +690,7 @@ extern void getOwnedSeqs(Archive *fout, TableInfo tblinfo[], int numTables);
 extern InhInfo *getInherits(Archive *fout, int *numInherits);
 extern PartInfo *getPartitions(Archive *fout, int *numPartitions);
 extern void getIndexes(Archive *fout, TableInfo tblinfo[], int numTables);
+extern void getExtendedStatistics(Archive *fout, TableInfo tblinfo[], int numTables);
 extern void getConstraints(Archive *fout, TableInfo tblinfo[], int numTables);
 extern RuleInfo *getRules(Archive *fout, int *numRules);
 extern void getTriggers(Archive *fout, TableInfo tblinfo[], int numTables);
diff --git a/src/bin/pg_dump/pg_dump_sort.c b/src/bin/pg_dump/pg_dump_sort.c
index ea64339..9ca58cc 100644
--- a/src/bin/pg_dump/pg_dump_sort.c
+++ b/src/bin/pg_dump/pg_dump_sort.c
@@ -48,10 +48,11 @@ static const int dbObjectTypePriority[] =
 	18,							/* DO_TABLE */
 	20,							/* DO_ATTRDEF */
 	28,							/* DO_INDEX */
-	29,							/* DO_RULE */
-	30,							/* DO_TRIGGER */
+	29,							/* DO_STATSEXT */
+	30,							/* DO_RULE */
+	31,							/* DO_TRIGGER */
 	27,							/* DO_CONSTRAINT */
-	31,							/* DO_FK_CONSTRAINT */
+	32,							/* DO_FK_CONSTRAINT */
 	2,							/* DO_PROCLANG */
 	10,							/* DO_CAST */
 	23,							/* DO_TABLE_DATA */
@@ -63,18 +64,18 @@ static const int dbObjectTypePriority[] =
 	15,							/* DO_TSCONFIG */
 	16,							/* DO_FDW */
 	17,							/* DO_FOREIGN_SERVER */
-	32,							/* DO_DEFAULT_ACL */
+	33,							/* DO_DEFAULT_ACL */
 	3,							/* DO_TRANSFORM */
 	21,							/* DO_BLOB */
 	25,							/* DO_BLOB_DATA */
 	22,							/* DO_PRE_DATA_BOUNDARY */
 	26,							/* DO_POST_DATA_BOUNDARY */
-	33,							/* DO_EVENT_TRIGGER */
-	34,							/* DO_REFRESH_MATVIEW */
-	35,							/* DO_POLICY */
-	36,							/* DO_PUBLICATION */
-	37,							/* DO_PUBLICATION_REL */
-	38							/* DO_SUBSCRIPTION */
+	34,							/* DO_EVENT_TRIGGER */
+	35,							/* DO_REFRESH_MATVIEW */
+	36,							/* DO_POLICY */
+	37,							/* DO_PUBLICATION */
+	38,							/* DO_PUBLICATION_REL */
+	39							/* DO_SUBSCRIPTION */
 };
 
 static DumpId preDataBoundId;
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 9bdeef0..340f1e5 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -1981,6 +1981,8 @@ DESCR("select statement of a view");
 DATA(insert OID = 1642 (  pg_get_userbyid	   PGNSP PGUID 12 1 0 0 0 f f f f t f s s 1 0 19 "26" _null_ _null_ _null_ _null_ _null_ pg_get_userbyid _null_ _null_ _null_ ));
 DESCR("role name by OID (with fallback)");
 DATA(insert OID = 1643 (  pg_get_indexdef	   PGNSP PGUID 12 1 0 0 0 f f f f t f s s 1 0 25 "26" _null_ _null_ _null_ _null_ _null_ pg_get_indexdef _null_ _null_ _null_ ));
+DESCR("extended statistics description");
+DATA(insert OID = 3353 (  pg_get_statisticsextdef	   PGNSP PGUID 12 1 0 0 0 f f f f t f s s 1 0 25 "26" _null_ _null_ _null_ _null_ _null_ pg_get_statisticsextdef _null_ _null_ _null_ ));
 DESCR("index description");
 DATA(insert OID = 3352 (  pg_get_partkeydef    PGNSP PGUID 12 1 0 0 0 f f f f t f s s 1 0 25 "26" _null_ _null_ _null_ _null_ _null_ pg_get_partkeydef _null_ _null_ _null_ ));
 DESCR("partition key description");