postgres
diff --git a/‎doc/src/sgml/ref/alter_statistics.sgml
Lines changed: 17 additions & 0 deletions b/‎doc/src/sgml/ref/alter_statistics.sgml
Lines changed: 17 additions & 0 deletions
diff --git a/‎src/backend/commands/analyze.c
Lines changed: 12 additions & 1 deletion b/‎src/backend/commands/analyze.c
Lines changed: 12 additions & 1 deletion
diff --git a/‎src/backend/commands/statscmds.c
Lines changed: 108 additions & 0 deletions b/‎src/backend/commands/statscmds.c
Lines changed: 108 additions & 0 deletions
diff --git a/‎src/backend/nodes/copyfuncs.c
Lines changed: 15 additions & 0 deletions b/‎src/backend/nodes/copyfuncs.c
Lines changed: 15 additions & 0 deletions
diff --git a/‎src/backend/nodes/equalfuncs.c
Lines changed: 13 additions & 0 deletions b/‎src/backend/nodes/equalfuncs.c
Lines changed: 13 additions & 0 deletions
diff --git a/‎src/backend/nodes/outfuncs.c
Lines changed: 13 additions & 0 deletions b/‎src/backend/nodes/outfuncs.c
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diff --git a/‎src/backend/parser/gram.y
Lines changed: 30 additions & 1 deletion b/‎src/backend/parser/gram.y
Lines changed: 30 additions & 1 deletion
@@ -26,6 +26,7 @@ PostgreSQL documentation
 ALTER STATISTICS <replaceable class="parameter">name</replaceable> OWNER TO { <replaceable class="parameter">new_owner</replaceable> | CURRENT_USER | SESSION_USER }
 ALTER STATISTICS <replaceable class="parameter">name</replaceable> RENAME TO <replaceable class="parameter">new_name</replaceable>
 ALTER STATISTICS <replaceable class="parameter">name</replaceable> SET SCHEMA <replaceable class="parameter">new_schema</replaceable>
+ALTER STATISTICS <replaceable class="parameter">name</replaceable> SET STATISTICS <replaceable class="parameter">new_target</replaceable>
 </synopsis>
  </refsynopsisdiv>
 
@@ -93,6 +94,22 @@ ALTER STATISTICS <replaceable class="parameter">name</replaceable> SET SCHEMA <r
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><replaceable class="parameter">new_target</replaceable></term>
+      <listitem>
+       <para>
+        The statistic-gathering target for this statistics object for subsequent
+        <xref linkend="sql-analyze"/> operations.
+        The target can be set in the range 0 to 10000; alternatively, set it
+        to -1 to revert to using the system default statistics
+        target (<xref linkend="guc-default-statistics-target"/>).
+        For more information on the use of statistics by the
+        <productname>PostgreSQL</productname> query planner, refer to
+        <xref linkend="planner-stats"/>.
+       </para>
+      </listitem>
+     </varlistentry>
+
     </variablelist>
    </para>
   </refsect1>
 
@@ -307,7 +307,8 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 	VacAttrStats **vacattrstats;
 	AnlIndexData *indexdata;
 	int			targrows,
-				numrows;
+				numrows,
+				minrows;
 	double		totalrows,
 				totaldeadrows;
 	HeapTuple  *rows;
@@ -491,6 +492,16 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 		}
 	}
 
+	/*
+	 * Look at extended statistics objects too, as those may define custom
+	 * statistics target. So we may need to sample more rows and then build
+	 * the statistics with enough detail.
+	 */
+	minrows = ComputeExtStatisticsRows(onerel, attr_cnt, vacattrstats);
+
+	if (targrows < minrows)
+		targrows = minrows;
+
 	/*
 	 * Acquire the sample rows
 	 */
 
@@ -14,13 +14,15 @@
  */
 #include "postgres.h"
 
+#include "access/heapam.h"
 #include "access/relation.h"
 #include "access/relscan.h"
 #include "access/table.h"
 #include "catalog/catalog.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
 #include "catalog/namespace.h"
+#include "catalog/objectaccess.h"
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_statistic_ext.h"
 #include "catalog/pg_statistic_ext_data.h"
@@ -29,6 +31,7 @@
 #include "miscadmin.h"
 #include "statistics/statistics.h"
 #include "utils/builtins.h"
+#include "utils/fmgroids.h"
 #include "utils/inval.h"
 #include "utils/memutils.h"
 #include "utils/rel.h"
@@ -336,6 +339,7 @@ CreateStatistics(CreateStatsStmt *stmt)
 	values[Anum_pg_statistic_ext_stxrelid - 1] = ObjectIdGetDatum(relid);
 	values[Anum_pg_statistic_ext_stxname - 1] = NameGetDatum(&stxname);
 	values[Anum_pg_statistic_ext_stxnamespace - 1] = ObjectIdGetDatum(namespaceId);
+	values[Anum_pg_statistic_ext_stxstattarget - 1] = Int32GetDatum(-1);
 	values[Anum_pg_statistic_ext_stxowner - 1] = ObjectIdGetDatum(stxowner);
 	values[Anum_pg_statistic_ext_stxkeys - 1] = PointerGetDatum(stxkeys);
 	values[Anum_pg_statistic_ext_stxkind - 1] = PointerGetDatum(stxkind);
@@ -414,6 +418,110 @@ CreateStatistics(CreateStatsStmt *stmt)
 	return myself;
 }
 
+/*
+ *		ALTER STATISTICS
+ */
+ObjectAddress
+AlterStatistics(AlterStatsStmt *stmt)
+{
+	Relation	rel;
+	Oid			stxoid;
+	HeapTuple	oldtup;
+	HeapTuple	newtup;
+	Datum		repl_val[Natts_pg_statistic_ext];
+	bool		repl_null[Natts_pg_statistic_ext];
+	bool		repl_repl[Natts_pg_statistic_ext];
+	ObjectAddress	address;
+	int			newtarget = stmt->stxstattarget;
+
+	/* Limit statistics target to a sane range */
+	if (newtarget < -1)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("statistics target %d is too low",
+						newtarget)));
+	}
+	else if (newtarget > 10000)
+	{
+		newtarget = 10000;
+		ereport(WARNING,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("lowering statistics target to %d",
+						newtarget)));
+	}
+
+	/* lookup OID of the statistics object */
+	stxoid = get_statistics_object_oid(stmt->defnames, stmt->missing_ok);
+
+	/*
+	 * If we got here and the OID is not valid, it means the statistics
+	 * does not exist, but the command specified IF EXISTS. So report
+	 * this as a simple NOTICE and we're done.
+	 */
+	if (!OidIsValid(stxoid))
+	{
+		char	   *schemaname;
+		char	   *statname;
+
+		Assert(stmt->missing_ok);
+
+		DeconstructQualifiedName(stmt->defnames, &schemaname, &statname);
+
+		if (schemaname)
+			ereport(NOTICE,
+					(errmsg("statistics object \"%s.%s\" does not exist, skipping",
+							schemaname, statname)));
+		else
+			ereport(NOTICE,
+					(errmsg("statistics object \"%s\" does not exist, skipping",
+							statname)));
+
+		return InvalidObjectAddress;
+	}
+
+	/* Search pg_statistic_ext */
+	rel = table_open(StatisticExtRelationId, RowExclusiveLock);
+
+	oldtup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(stxoid));
+
+	/* Must be owner of the existing statistics object */
+	if (!pg_statistics_object_ownercheck(stxoid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_STATISTIC_EXT,
+					   NameListToString(stmt->defnames));
+
+	/* Build new tuple. */
+	memset(repl_val, 0, sizeof(repl_val));
+	memset(repl_null, false, sizeof(repl_null));
+	memset(repl_repl, false, sizeof(repl_repl));
+
+	/* replace the stxstattarget column */
+	repl_repl[Anum_pg_statistic_ext_stxstattarget - 1] = true;
+	repl_val[Anum_pg_statistic_ext_stxstattarget - 1] = Int32GetDatum(newtarget);
+
+	newtup = heap_modify_tuple(oldtup, RelationGetDescr(rel),
+							   repl_val, repl_null, repl_repl);
+
+	/* Update system catalog. */
+	CatalogTupleUpdate(rel, &newtup->t_self, newtup);
+
+	InvokeObjectPostAlterHook(StatisticExtRelationId, stxoid, 0);
+
+	ObjectAddressSet(address, StatisticExtRelationId, stxoid);
+
+	/*
+	 * NOTE: because we only support altering the statistics target, not the
+	 * other fields, there is no need to update dependencies.
+	 */
+
+	heap_freetuple(newtup);
+	ReleaseSysCache(oldtup);
+
+	table_close(rel, RowExclusiveLock);
+
+	return address;
+}
+
 /*
  * Guts of statistics object deletion.
  */
 
@@ -3497,6 +3497,18 @@ _copyCreateStatsStmt(const CreateStatsStmt *from)
 	return newnode;
 }
 
+static AlterStatsStmt *
+_copyAlterStatsStmt(const AlterStatsStmt *from)
+{
+	AlterStatsStmt *newnode = makeNode(AlterStatsStmt);
+
+	COPY_NODE_FIELD(defnames);
+	COPY_SCALAR_FIELD(stxstattarget);
+	COPY_SCALAR_FIELD(missing_ok);
+
+	return newnode;
+}
+
 static CreateFunctionStmt *
 _copyCreateFunctionStmt(const CreateFunctionStmt *from)
 {
@@ -5211,6 +5223,9 @@ copyObjectImpl(const void *from)
 		case T_CreateStatsStmt:
 			retval = _copyCreateStatsStmt(from);
 			break;
+		case T_AlterStatsStmt:
+			retval = _copyAlterStatsStmt(from);
+			break;
 		case T_CreateFunctionStmt:
 			retval = _copyCreateFunctionStmt(from);
 			break;
 
@@ -1365,6 +1365,16 @@ _equalCreateStatsStmt(const CreateStatsStmt *a, const CreateStatsStmt *b)
 	return true;
 }
 
+static bool
+_equalAlterStatsStmt(const AlterStatsStmt *a, const AlterStatsStmt *b)
+{
+	COMPARE_NODE_FIELD(defnames);
+	COMPARE_SCALAR_FIELD(stxstattarget);
+	COMPARE_SCALAR_FIELD(missing_ok);
+
+	return true;
+}
+
 static bool
 _equalCreateFunctionStmt(const CreateFunctionStmt *a, const CreateFunctionStmt *b)
 {
@@ -3309,6 +3319,9 @@ equal(const void *a, const void *b)
 		case T_CreateStatsStmt:
 			retval = _equalCreateStatsStmt(a, b);
 			break;
+		case T_AlterStatsStmt:
+			retval = _equalAlterStatsStmt(a, b);
+			break;
 		case T_CreateFunctionStmt:
 			retval = _equalCreateFunctionStmt(a, b);
 			break;
 
@@ -2668,6 +2668,16 @@ _outCreateStatsStmt(StringInfo str, const CreateStatsStmt *node)
 	WRITE_BOOL_FIELD(if_not_exists);
 }
 
+static void
+_outAlterStatsStmt(StringInfo str, const AlterStatsStmt *node)
+{
+	WRITE_NODE_TYPE("ALTERSTATSSTMT");
+
+	WRITE_NODE_FIELD(defnames);
+	WRITE_INT_FIELD(stxstattarget);
+	WRITE_BOOL_FIELD(missing_ok);
+}
+
 static void
 _outNotifyStmt(StringInfo str, const NotifyStmt *node)
 {
@@ -4130,6 +4140,9 @@ outNode(StringInfo str, const void *obj)
 			case T_CreateStatsStmt:
 				_outCreateStatsStmt(str, obj);
 				break;
+			case T_AlterStatsStmt:
+				_outAlterStatsStmt(str, obj);
+				break;
 			case T_NotifyStmt:
 				_outNotifyStmt(str, obj);
 				break;
 
@@ -252,7 +252,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 		AlterOperatorStmt AlterSeqStmt AlterSystemStmt AlterTableStmt
 		AlterTblSpcStmt AlterExtensionStmt AlterExtensionContentsStmt AlterForeignTableStmt
 		AlterCompositeTypeStmt AlterUserMappingStmt
-		AlterRoleStmt AlterRoleSetStmt AlterPolicyStmt
+		AlterRoleStmt AlterRoleSetStmt AlterPolicyStmt AlterStatsStmt
 		AlterDefaultPrivilegesStmt DefACLAction
 		AnalyzeStmt CallStmt ClosePortalStmt ClusterStmt CommentStmt
 		ConstraintsSetStmt CopyStmt CreateAsStmt CreateCastStmt
@@ -852,6 +852,7 @@ stmt :
 			| AlterRoleSetStmt
 			| AlterRoleStmt
 			| AlterSubscriptionStmt
+			| AlterStatsStmt
 			| AlterTSConfigurationStmt
 			| AlterTSDictionaryStmt
 			| AlterUserMappingStmt
@@ -3984,6 +3985,34 @@ CreateStatsStmt:
 				}
 			;
 
+
+/*****************************************************************************
+ *
+ *		QUERY :
+ *				ALTER STATISTICS [IF EXISTS] stats_name
+ *					SET STATISTICS  <SignedIconst>
+ *
+ *****************************************************************************/
+
+AlterStatsStmt:
+			ALTER STATISTICS any_name SET STATISTICS SignedIconst
+				{
+					AlterStatsStmt *n = makeNode(AlterStatsStmt);
+					n->defnames = $3;
+					n->missing_ok = false;
+					n->stxstattarget = $6;
+					$$ = (Node *)n;
+				}
+			| ALTER STATISTICS IF_P EXISTS any_name SET STATISTICS SignedIconst
+				{
+					AlterStatsStmt *n = makeNode(AlterStatsStmt);
+					n->defnames = $5;
+					n->missing_ok = true;
+					n->stxstattarget = $8;
+					$$ = (Node *)n;
+				}
+			;
+
 /*****************************************************************************
  *
  *		QUERY :