v3-0001-Make-attstattarget-nullable.patch

From d937c26d8c471c999aa53c96dce86c68fad71a7a Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Thu, 11 Jan 2024 10:09:02 +0100
Subject: [PATCH v3 1/3] Make attstattarget nullable

This changes the pg_attribute field attstattarget into a nullable
field in the variable-length part of the row.  If no value is set by
the user for attstattarget, it is now null instead of previously -1.
This saves space in pg_attribute and tuple descriptors for most
practical scenarios.  (ATTRIBUTE_FIXED_PART_SIZE is reduced from 108
to 104.)  Also, null is the semantically more correct value.

The ANALYZE code internally continues to represent the default
statistics target by -1, so that that code can avoid having to deal
with null values.  But that is now contained to the ANALYZE code.
Only the DDL code deals with attstattarget possibly null.

For system columns, the field is now always null.  The ANALYZE code
skips system columns anyway.

To set a column's statistics target to the default value, the new
command form ALTER TABLE ... SET STATISTICS DEFAULT can be used.  (SET
STATISTICS -1 still works.)

Discussion: https://www.postgresql.org/message-id/flat/4da8d211-d54d-44b9-9847-f2a9f1184c76@eisentraut.org

TODO: catversion
---
 doc/src/sgml/ref/alter_table.sgml          | 10 +++--
 src/backend/access/common/tupdesc.c        |  4 --
 src/backend/bootstrap/bootstrap.c          |  1 -
 src/backend/catalog/genbki.pl              |  1 -
 src/backend/catalog/heap.c                 | 18 ++++-----
 src/backend/catalog/index.c                | 21 ++++++++---
 src/backend/commands/analyze.c             | 21 ++++++++++-
 src/backend/commands/tablecmds.c           | 44 +++++++++++++++++-----
 src/backend/parser/gram.y                  | 18 ++++++---
 src/backend/utils/cache/lsyscache.c        | 27 -------------
 src/bin/pg_dump/pg_dump.c                  |  7 +++-
 src/include/catalog/pg_attribute.h         | 16 ++++----
 src/include/commands/vacuum.h              |  2 +-
 src/include/utils/lsyscache.h              |  1 -
 src/test/regress/expected/create_index.out |  4 +-
 15 files changed, 110 insertions(+), 85 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index eaada230248..9670671107e 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -51,7 +51,7 @@
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> { SET GENERATED { ALWAYS | BY DEFAULT } | SET <replaceable>sequence_option</replaceable> | RESTART [ [ WITH ] <replaceable class="parameter">restart</replaceable> ] } [...]
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> DROP IDENTITY [ IF EXISTS ]
-    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STATISTICS <replaceable class="parameter">integer</replaceable>
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STATISTICS { <replaceable class="parameter">integer</replaceable> | DEFAULT }
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN | DEFAULT }
@@ -328,9 +328,11 @@ <title>Description</title>
       This form
       sets the per-column statistics-gathering target for subsequent
       <link linkend="sql-analyze"><command>ANALYZE</command></link> 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"/>).
+      The target can be set in the range 0 to 10000.  Set it
+      to <literal>DEFAULT</literal> to revert to using the system default
+      statistics target (<xref linkend="guc-default-statistics-target"/>).
+      (Setting to a value of -1 is an obsolete way spelling to get the same
+      outcome.)
       For more information on the use of statistics by the
       <productname>PostgreSQL</productname> query planner, refer to
       <xref linkend="planner-stats"/>.
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 6e7ad79834f..bc80caee117 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -453,8 +453,6 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 			return false;
 		if (attr1->atttypid != attr2->atttypid)
 			return false;
-		if (attr1->attstattarget != attr2->attstattarget)
-			return false;
 		if (attr1->attlen != attr2->attlen)
 			return false;
 		if (attr1->attndims != attr2->attndims)
@@ -639,7 +637,6 @@ TupleDescInitEntry(TupleDesc desc,
 	else if (attributeName != NameStr(att->attname))
 		namestrcpy(&(att->attname), attributeName);
 
-	att->attstattarget = -1;
 	att->attcacheoff = -1;
 	att->atttypmod = typmod;
 
@@ -702,7 +699,6 @@ TupleDescInitBuiltinEntry(TupleDesc desc,
 	Assert(attributeName != NULL);
 	namestrcpy(&(att->attname), attributeName);
 
-	att->attstattarget = -1;
 	att->attcacheoff = -1;
 	att->atttypmod = typmod;
 
diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 55c53d01f87..141b25ddd7a 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -552,7 +552,6 @@ DefineAttr(char *name, char *type, int attnum, int nullness)
 	if (OidIsValid(attrtypes[attnum]->attcollation))
 		attrtypes[attnum]->attcollation = C_COLLATION_OID;
 
-	attrtypes[attnum]->attstattarget = -1;
 	attrtypes[attnum]->attcacheoff = -1;
 	attrtypes[attnum]->atttypmod = -1;
 	attrtypes[attnum]->attislocal = true;
diff --git a/src/backend/catalog/genbki.pl b/src/backend/catalog/genbki.pl
index 531d7cd0d52..93553e8c3c4 100644
--- a/src/backend/catalog/genbki.pl
+++ b/src/backend/catalog/genbki.pl
@@ -840,7 +840,6 @@ sub gen_pg_attribute
 				my %row;
 				$row{attnum} = $attnum;
 				$row{attrelid} = $table->{relation_oid};
-				$row{attstattarget} = '0';
 
 				morph_row_for_pgattr(\%row, $schema, $attr, 1);
 				print_bki_insert(\%row, $schema);
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index e80a90ef4c0..45a71081d42 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -749,14 +749,16 @@ InsertPgAttributeTuples(Relation pg_attribute_rel,
 		slot[slotCount]->tts_values[Anum_pg_attribute_attisdropped - 1] = BoolGetDatum(attrs->attisdropped);
 		slot[slotCount]->tts_values[Anum_pg_attribute_attislocal - 1] = BoolGetDatum(attrs->attislocal);
 		slot[slotCount]->tts_values[Anum_pg_attribute_attinhcount - 1] = Int16GetDatum(attrs->attinhcount);
-		slot[slotCount]->tts_values[Anum_pg_attribute_attstattarget - 1] = Int16GetDatum(attrs->attstattarget);
 		slot[slotCount]->tts_values[Anum_pg_attribute_attcollation - 1] = ObjectIdGetDatum(attrs->attcollation);
 		if (attoptions && attoptions[natts] != (Datum) 0)
 			slot[slotCount]->tts_values[Anum_pg_attribute_attoptions - 1] = attoptions[natts];
 		else
 			slot[slotCount]->tts_isnull[Anum_pg_attribute_attoptions - 1] = true;
 
-		/* start out with empty permissions and empty options */
+		/*
+		 * The remaining fields are not set for new columns.
+		 */
+		slot[slotCount]->tts_isnull[Anum_pg_attribute_attstattarget - 1] = true;
 		slot[slotCount]->tts_isnull[Anum_pg_attribute_attacl - 1] = true;
 		slot[slotCount]->tts_isnull[Anum_pg_attribute_attfdwoptions - 1] = true;
 		slot[slotCount]->tts_isnull[Anum_pg_attribute_attmissingval - 1] = true;
@@ -818,9 +820,6 @@ AddNewAttributeTuples(Oid new_rel_oid,
 
 	indstate = CatalogOpenIndexes(rel);
 
-	/* set stats detail level to a sane default */
-	for (int i = 0; i < natts; i++)
-		tupdesc->attrs[i].attstattarget = -1;
 	InsertPgAttributeTuples(rel, tupdesc, new_rel_oid, NULL, indstate);
 
 	/* add dependencies on their datatypes and collations */
@@ -1685,9 +1684,6 @@ RemoveAttributeById(Oid relid, AttrNumber attnum)
 	/* Remove any not-null constraint the column may have */
 	attStruct->attnotnull = false;
 
-	/* We don't want to keep stats for it anymore */
-	attStruct->attstattarget = 0;
-
 	/* Unset this so no one tries to look up the generation expression */
 	attStruct->attgenerated = '\0';
 
@@ -1704,9 +1700,11 @@ RemoveAttributeById(Oid relid, AttrNumber attnum)
 	replacesAtt[Anum_pg_attribute_attmissingval - 1] = true;
 
 	/*
-	 * Clear the other variable-length fields.  This saves some space in
-	 * pg_attribute and removes no longer useful information.
+	 * Clear the other nullable fields.  This saves some space in pg_attribute
+	 * and removes no longer useful information.
 	 */
+	nullsAtt[Anum_pg_attribute_attstattarget - 1] = true;
+	replacesAtt[Anum_pg_attribute_attstattarget - 1] = true;
 	nullsAtt[Anum_pg_attribute_attacl - 1] = true;
 	replacesAtt[Anum_pg_attribute_attacl - 1] = true;
 	nullsAtt[Anum_pg_attribute_attoptions - 1] = true;
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 88f7994b5a6..fbef3d5382d 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -325,7 +325,6 @@ ConstructTupleDescriptor(Relation heapRelation,
 
 		MemSet(to, 0, ATTRIBUTE_FIXED_PART_SIZE);
 		to->attnum = i + 1;
-		to->attstattarget = -1;
 		to->attcacheoff = -1;
 		to->attislocal = true;
 		to->attcollation = (i < numkeyatts) ? collationIds[i] : InvalidOid;
@@ -1780,10 +1779,12 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName)
 		while (HeapTupleIsValid((attrTuple = systable_getnext(scan))))
 		{
 			Form_pg_attribute att = (Form_pg_attribute) GETSTRUCT(attrTuple);
+			HeapTuple	tp;
+			Datum		dat;
+			bool		isnull;
 			Datum		repl_val[Natts_pg_attribute];
 			bool		repl_null[Natts_pg_attribute];
 			bool		repl_repl[Natts_pg_attribute];
-			int			attstattarget;
 			HeapTuple	newTuple;
 
 			/* Ignore dropped columns */
@@ -1793,10 +1794,18 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName)
 			/*
 			 * Get attstattarget from the old index and refresh the new value.
 			 */
-			attstattarget = get_attstattarget(oldIndexId, att->attnum);
+			tp = SearchSysCache2(ATTNUM, ObjectIdGetDatum(oldIndexId), Int16GetDatum(att->attnum));
+			if (!HeapTupleIsValid(tp))
+				elog(ERROR, "cache lookup failed for attribute %d of relation %u",
+					 att->attnum, oldIndexId);
+			dat = SysCacheGetAttr(ATTNUM, tp, Anum_pg_attribute_attstattarget, &isnull);
+			ReleaseSysCache(tp);
 
-			/* no need for a refresh if both match */
-			if (attstattarget == att->attstattarget)
+			/*
+			 * No need for a refresh if old index value is null.  (All new
+			 * index values are null at this point.)
+			 */
+			if (isnull)
 				continue;
 
 			memset(repl_val, 0, sizeof(repl_val));
@@ -1804,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName)
 			memset(repl_repl, false, sizeof(repl_repl));
 
 			repl_repl[Anum_pg_attribute_attstattarget - 1] = true;
-			repl_val[Anum_pg_attribute_attstattarget - 1] = Int16GetDatum(attstattarget);
+			repl_val[Anum_pg_attribute_attstattarget - 1] = dat;
 
 			newTuple = heap_modify_tuple(attrTuple,
 										 RelationGetDescr(pg_attribute),
diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index deef865ce6d..a03495d6c95 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -1004,6 +1004,10 @@ static VacAttrStats *
 examine_attribute(Relation onerel, int attnum, Node *index_expr)
 {
 	Form_pg_attribute attr = TupleDescAttr(onerel->rd_att, attnum - 1);
+	int			attstattarget;
+	HeapTuple	atttuple;
+	Datum		dat;
+	bool		isnull;
 	HeapTuple	typtuple;
 	VacAttrStats *stats;
 	int			i;
@@ -1013,15 +1017,28 @@ examine_attribute(Relation onerel, int attnum, Node *index_expr)
 	if (attr->attisdropped)
 		return NULL;
 
+	/*
+	 * Get attstattarget value.  Set to -1 if null.  (Analyze functions expect
+	 * -1 to mean use default_statistics_target; see for example
+	 * std_typanalyze.)
+	 */
+	atttuple = SearchSysCache2(ATTNUM, ObjectIdGetDatum(RelationGetRelid(onerel)), Int16GetDatum(attnum));
+	if (!HeapTupleIsValid(atttuple))
+		elog(ERROR, "cache lookup failed for attribute %d of relation %u",
+			 attnum, RelationGetRelid(onerel));
+	dat = SysCacheGetAttr(ATTNUM, atttuple, Anum_pg_attribute_attstattarget, &isnull);
+	attstattarget = isnull ? -1 : DatumGetInt16(dat);
+	ReleaseSysCache(atttuple);
+
 	/* Don't analyze column if user has specified not to */
-	if (attr->attstattarget == 0)
+	if (attstattarget == 0)
 		return NULL;
 
 	/*
 	 * Create the VacAttrStats struct.
 	 */
 	stats = (VacAttrStats *) palloc0(sizeof(VacAttrStats));
-	stats->attstattarget = attr->attstattarget;
+	stats->attstattarget = attstattarget;
 
 	/*
 	 * When analyzing an expression index, believe the expression tree's type
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 2822b2bb440..86a70599062 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -7143,7 +7143,6 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	attribute.attrelid = myrelid;
 	namestrcpy(&(attribute.attname), colDef->colname);
 	attribute.atttypid = typeOid;
-	attribute.attstattarget = -1;
 	attribute.attlen = tform->typlen;
 	attribute.attnum = newattnum;
 	if (list_length(colDef->typeName->arrayBounds) > PG_INT16_MAX)
@@ -8588,10 +8587,14 @@ ATExecSetStatistics(Relation rel, const char *colName, int16 colNum, Node *newVa
 {
 	int			newtarget;
 	Relation	attrelation;
-	HeapTuple	tuple;
+	HeapTuple	tuple,
+				newtuple;
 	Form_pg_attribute attrtuple;
 	AttrNumber	attnum;
 	ObjectAddress address;
+	Datum		repl_val[Natts_pg_attribute];
+	bool		repl_null[Natts_pg_attribute];
+	bool		repl_repl[Natts_pg_attribute];
 
 	/*
 	 * We allow referencing columns by numbers only for indexes, since table
@@ -8604,8 +8607,18 @@ ATExecSetStatistics(Relation rel, const char *colName, int16 colNum, Node *newVa
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot refer to non-index column by number")));
 
-	Assert(IsA(newValue, Integer));
-	newtarget = intVal(newValue);
+	if (newValue)
+	{
+		Assert(IsA(newValue, Integer));
+		newtarget = intVal(newValue);
+	}
+	else
+	{
+		/*
+		 * -1 was used in previous versions to represent the default setting
+		 */
+		newtarget = -1;
+	}
 
 	/*
 	 * Limit target to a sane range
@@ -8630,7 +8643,7 @@ ATExecSetStatistics(Relation rel, const char *colName, int16 colNum, Node *newVa
 
 	if (colName)
 	{
-		tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+		tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
 
 		if (!HeapTupleIsValid(tuple))
 			ereport(ERROR,
@@ -8640,7 +8653,7 @@ ATExecSetStatistics(Relation rel, const char *colName, int16 colNum, Node *newVa
 	}
 	else
 	{
-		tuple = SearchSysCacheCopyAttNum(RelationGetRelid(rel), colNum);
+		tuple = SearchSysCacheAttNum(RelationGetRelid(rel), colNum);
 
 		if (!HeapTupleIsValid(tuple))
 			ereport(ERROR,
@@ -8674,16 +8687,27 @@ ATExecSetStatistics(Relation rel, const char *colName, int16 colNum, Node *newVa
 					 errhint("Alter statistics on table column instead.")));
 	}
 
-	attrtuple->attstattarget = newtarget;
-
-	CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+	/* Build new tuple. */
+	memset(repl_null, false, sizeof(repl_null));
+	memset(repl_repl, false, sizeof(repl_repl));
+	if (newtarget != -1)
+		repl_val[Anum_pg_attribute_attstattarget - 1] = newtarget;
+	else
+		repl_null[Anum_pg_attribute_attstattarget - 1] = true;
+	repl_repl[Anum_pg_attribute_attstattarget - 1] = true;
+	newtuple = heap_modify_tuple(tuple, RelationGetDescr(attrelation),
+								 repl_val, repl_null, repl_repl);
+	CatalogTupleUpdate(attrelation, &tuple->t_self, newtuple);
 
 	InvokeObjectPostAlterHook(RelationRelationId,
 							  RelationGetRelid(rel),
 							  attrtuple->attnum);
 	ObjectAddressSubSet(address, RelationRelationId,
 						RelationGetRelid(rel), attnum);
-	heap_freetuple(tuple);
+
+	heap_freetuple(newtuple);
+
+	ReleaseSysCache(tuple);
 
 	table_close(attrelation, RowExclusiveLock);
 
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 6b88096e8e1..3460fea56ba 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -337,6 +337,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <list>	alter_table_cmds alter_type_cmds
 %type <list>    alter_identity_column_option_list
 %type <defelt>  alter_identity_column_option
+%type <node>	set_statistics_value
 
 %type <list>	createdb_opt_list createdb_opt_items copy_opt_list
 				transaction_mode_list
@@ -2446,18 +2447,18 @@ alter_table_cmd:
 					n->missing_ok = true;
 					$$ = (Node *) n;
 				}
-			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET STATISTICS <SignedIconst> */
-			| ALTER opt_column ColId SET STATISTICS SignedIconst
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET STATISTICS */
+			| ALTER opt_column ColId SET STATISTICS set_statistics_value
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);
 
 					n->subtype = AT_SetStatistics;
 					n->name = $3;
-					n->def = (Node *) makeInteger($6);
+					n->def = $6;
 					$$ = (Node *) n;
 				}
-			/* ALTER TABLE <name> ALTER [COLUMN] <colnum> SET STATISTICS <SignedIconst> */
-			| ALTER opt_column Iconst SET STATISTICS SignedIconst
+			/* ALTER TABLE <name> ALTER [COLUMN] <colnum> SET STATISTICS */
+			| ALTER opt_column Iconst SET STATISTICS set_statistics_value
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);
 
@@ -2469,7 +2470,7 @@ alter_table_cmd:
 
 					n->subtype = AT_SetStatistics;
 					n->num = (int16) $3;
-					n->def = (Node *) makeInteger($6);
+					n->def = $6;
 					$$ = (Node *) n;
 				}
 			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET ( column_parameter = value [, ... ] ) */
@@ -3070,6 +3071,11 @@ alter_identity_column_option:
 				}
 		;
 
+set_statistics_value:
+			SignedIconst					{ $$ = (Node *) makeInteger($1); }
+			| DEFAULT						{ $$ = NULL; }
+		;
+
 PartitionBoundSpec:
 			/* a HASH partition */
 			FOR VALUES WITH '(' hash_partbound ')'
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 8ec83561bfa..f730aa26c47 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -872,33 +872,6 @@ get_attnum(Oid relid, const char *attname)
 		return InvalidAttrNumber;
 }
 
-/*
- * get_attstattarget
- *
- *		Given the relation id and the attribute number,
- *		return the "attstattarget" field from the attribute relation.
- *
- *		Errors if not found.
- */
-int
-get_attstattarget(Oid relid, AttrNumber attnum)
-{
-	HeapTuple	tp;
-	Form_pg_attribute att_tup;
-	int			result;
-
-	tp = SearchSysCache2(ATTNUM,
-						 ObjectIdGetDatum(relid),
-						 Int16GetDatum(attnum));
-	if (!HeapTupleIsValid(tp))
-		elog(ERROR, "cache lookup failed for attribute %d of relation %u",
-			 attnum, relid);
-	att_tup = (Form_pg_attribute) GETSTRUCT(tp);
-	result = att_tup->attstattarget;
-	ReleaseSysCache(tp);
-	return result;
-}
-
 /*
  * get_attgenerated
  *
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 22d1e6cf922..d4a888f5f13 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -8925,7 +8925,10 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 						 tbinfo->dobj.name);
 			tbinfo->attnames[j] = pg_strdup(PQgetvalue(res, r, i_attname));
 			tbinfo->atttypnames[j] = pg_strdup(PQgetvalue(res, r, i_atttypname));
-			tbinfo->attstattarget[j] = atoi(PQgetvalue(res, r, i_attstattarget));
+			if (PQgetisnull(res, r, i_attstattarget))
+				tbinfo->attstattarget[j] = -1;
+			else
+				tbinfo->attstattarget[j] = atoi(PQgetvalue(res, r, i_attstattarget));
 			tbinfo->attstorage[j] = *(PQgetvalue(res, r, i_attstorage));
 			tbinfo->typstorage[j] = *(PQgetvalue(res, r, i_typstorage));
 			tbinfo->attidentity[j] = *(PQgetvalue(res, r, i_attidentity));
@@ -16507,7 +16510,7 @@ dumpTableSchema(Archive *fout, const TableInfo *tbinfo)
 			/*
 			 * Dump per-column statistics information. We only issue an ALTER
 			 * TABLE statement if the attstattarget entry for this column is
-			 * non-negative (i.e. it's not the default value)
+			 * not the default value.
 			 */
 			if (tbinfo->attstattarget[j] >= 0)
 				appendPQExpBuffer(q, "ALTER %sTABLE ONLY %s ALTER COLUMN %s SET STATISTICS %d;\n",
diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index 7f4d308e8dd..1a487441e50 100644
--- a/src/include/catalog/pg_attribute.h
+++ b/src/include/catalog/pg_attribute.h
@@ -158,22 +158,22 @@ CATALOG(pg_attribute,1249,AttributeRelationId) BKI_BOOTSTRAP BKI_ROWTYPE_OID(75,
 	/* Number of times inherited from direct parent relation(s) */
 	int16		attinhcount BKI_DEFAULT(0);
 
+	/* attribute's collation, if any */
+	Oid			attcollation BKI_LOOKUP_OPT(pg_collation);
+
+#ifdef CATALOG_VARLEN			/* variable-length/nullable fields start here */
+	/* NOTE: The following fields are not present in tuple descriptors. */
+
 	/*
 	 * attstattarget is the target number of statistics datapoints to collect
 	 * during VACUUM ANALYZE of this column.  A zero here indicates that we do
-	 * not wish to collect any stats about this column. A "-1" here indicates
+	 * not wish to collect any stats about this column. A NULL here indicates
 	 * that no value has been explicitly set for this column, so ANALYZE
 	 * should use the default setting.
 	 *
 	 * int16 is sufficient for the current max value (MAX_STATISTICS_TARGET).
 	 */
-	int16		attstattarget BKI_DEFAULT(-1);
-
-	/* attribute's collation, if any */
-	Oid			attcollation BKI_LOOKUP_OPT(pg_collation);
-
-#ifdef CATALOG_VARLEN			/* variable-length fields start here */
-	/* NOTE: The following fields are not present in tuple descriptors. */
+	int16		attstattarget BKI_DEFAULT(_null_) BKI_FORCE_NULL;
 
 	/* Column-level access permissions */
 	aclitem		attacl[1] BKI_DEFAULT(_null_);
diff --git a/src/include/commands/vacuum.h b/src/include/commands/vacuum.h
index 5cacefc7670..7f623b37fdc 100644
--- a/src/include/commands/vacuum.h
+++ b/src/include/commands/vacuum.h
@@ -121,7 +121,7 @@ typedef struct VacAttrStats
 	 * than the underlying column/expression.  Therefore, use these fields for
 	 * information about the datatype being fed to the typanalyze function.
 	 */
-	int			attstattarget;
+	int			attstattarget;	/* -1 to use default */
 	Oid			attrtypid;		/* type of data being analyzed */
 	int32		attrtypmod;		/* typmod of data being analyzed */
 	Form_pg_type attrtype;		/* copy of pg_type row for attrtypid */
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index be9ed70e841..e4a200b00ec 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -90,7 +90,6 @@ extern Oid	get_opfamily_proc(Oid opfamily, Oid lefttype, Oid righttype,
 							  int16 procnum);
 extern char *get_attname(Oid relid, AttrNumber attnum, bool missing_ok);
 extern AttrNumber get_attnum(Oid relid, const char *attname);
-extern int	get_attstattarget(Oid relid, AttrNumber attnum);
 extern char get_attgenerated(Oid relid, AttrNumber attnum);
 extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index 446cfa678b7..79fa117cb54 100644
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -2707,8 +2707,8 @@ SELECT attrelid::regclass, attnum, attstattarget
          attrelid          | attnum | attstattarget 
 ---------------------------+--------+---------------
  concur_exprs_index_expr   |      1 |           100
- concur_exprs_index_pred   |      1 |            -1
- concur_exprs_index_pred_2 |      1 |            -1
+ concur_exprs_index_pred   |      1 |              
+ concur_exprs_index_pred_2 |      1 |              
 (3 rows)
 
 DROP TABLE concur_exprs_tab;

base-commit: 6f97ef05d62a9c4ed5c53e98ac8a44cf3e0a2780
-- 
2.43.0