1 files changed, 98 insertions, 6 deletions

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index efac06f72c7..88a68a4697a 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -41,6 +41,7 @@
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_opclass.h"
 #include "catalog/pg_tablespace.h"
+#include "catalog/pg_statistic_ext.h"
 #include "catalog/pg_trigger.h"
 #include "catalog/pg_type.h"
 #include "catalog/storage.h"
@@ -188,6 +189,8 @@ typedef struct AlteredTableInfo
 	List	   *changedIndexDefs;	/* string definitions of same */
 	char	   *replicaIdentityIndex;	/* index to reset as REPLICA IDENTITY */
 	char	   *clusterOnIndex; /* index to use for CLUSTER */
+	List	   *changedStatisticsOids;	/* OIDs of statistics to rebuild */
+	List	   *changedStatisticsDefs;	/* string definitions of same */
 } AlteredTableInfo;
 
 /* Struct describing one new constraint to check in Phase 3 scan */
@@ -440,6 +443,8 @@ static ObjectAddress ATExecDropColumn(List **wqueue, Relation rel, const char *c
 									  ObjectAddresses *addrs);
 static ObjectAddress ATExecAddIndex(AlteredTableInfo *tab, Relation rel,
 									IndexStmt *stmt, bool is_rebuild, LOCKMODE lockmode);
+static ObjectAddress ATExecAddStatistics(AlteredTableInfo *tab, Relation rel,
+										 CreateStatsStmt *stmt, bool is_rebuild, LOCKMODE lockmode);
 static ObjectAddress ATExecAddConstraint(List **wqueue,
 										 AlteredTableInfo *tab, Relation rel,
 										 Constraint *newConstraint, bool recurse, bool is_readd,
@@ -496,6 +501,7 @@ static ObjectAddress ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 										   AlterTableCmd *cmd, LOCKMODE lockmode);
 static void RememberConstraintForRebuilding(Oid conoid, AlteredTableInfo *tab);
 static void RememberIndexForRebuilding(Oid indoid, AlteredTableInfo *tab);
+static void RememberStatisticsForRebuilding(Oid indoid, AlteredTableInfo *tab);
 static void ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab,
 								   LOCKMODE lockmode);
 static void ATPostAlterTypeParse(Oid oldId, Oid oldRelId, Oid refRelId,
@@ -4756,6 +4762,10 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 			address = ATExecAddIndex(tab, rel, (IndexStmt *) cmd->def, true,
 									 lockmode);
 			break;
+		case AT_ReAddStatistics:	/* ADD STATISTICS */
+			address = ATExecAddStatistics(tab, rel, (CreateStatsStmt *) cmd->def,
+										  true, lockmode);
+			break;
 		case AT_AddConstraint:	/* ADD CONSTRAINT */
 			/* Transform the command only during initial examination */
 			if (cur_pass == AT_PASS_ADD_CONSTR)
@@ -8284,6 +8294,29 @@ ATExecAddIndex(AlteredTableInfo *tab, Relation rel,
 }
 
 /*
+ * ALTER TABLE ADD STATISTICS
+ *
+ * This is no such command in the grammar, but we use this internally to add
+ * AT_ReAddStatistics subcommands to rebuild extended statistics after a table
+ * column type change.
+ */
+static ObjectAddress
+ATExecAddStatistics(AlteredTableInfo *tab, Relation rel,
+					CreateStatsStmt *stmt, bool is_rebuild, LOCKMODE lockmode)
+{
+	ObjectAddress address;
+
+	Assert(IsA(stmt, CreateStatsStmt));
+
+	/* The CreateStatsStmt has already been through transformStatsStmt */
+	Assert(stmt->transformed);
+
+	address = CreateStatistics(stmt);
+
+	return address;
+}
+
+/*
  * ALTER TABLE ADD CONSTRAINT USING INDEX
  *
  * Returns the address of the new constraint.
@@ -11830,9 +11863,7 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 				 * Give the extended-stats machinery a chance to fix anything
 				 * that this column type change would break.
 				 */
-				UpdateStatisticsForTypeChange(foundObject.objectId,
-											  RelationGetRelid(rel), attnum,
-											  attTup->atttypid, targettype);
+				RememberStatisticsForRebuilding(foundObject.objectId, tab);
 				break;
 
 			case OCLASS_PROC:
@@ -12203,6 +12234,32 @@ RememberIndexForRebuilding(Oid indoid, AlteredTableInfo *tab)
 }
 
 /*
+ * Subroutine for ATExecAlterColumnType: remember that a statistics object
+ * needs to be rebuilt (which we might already know).
+ */
+static void
+RememberStatisticsForRebuilding(Oid stxoid, AlteredTableInfo *tab)
+{
+	/*
+	 * This de-duplication check is critical for two independent reasons: we
+	 * mustn't try to recreate the same statistics object twice, and if the
+	 * statistics depends on more than one column whose type is to be altered,
+	 * we must capture its definition string before applying any of the type
+	 * changes. ruleutils.c will get confused if we ask again later.
+	 */
+	if (!list_member_oid(tab->changedStatisticsOids, stxoid))
+	{
+		/* OK, capture the index's existing definition string */
+		char	   *defstring = pg_get_statisticsobjdef_string(stxoid);
+
+		tab->changedStatisticsOids = lappend_oid(tab->changedStatisticsOids,
+												 stxoid);
+		tab->changedStatisticsDefs = lappend(tab->changedStatisticsDefs,
+											 defstring);
+	}
+}
+
+/*
  * Cleanup after we've finished all the ALTER TYPE operations for a
  * particular relation.  We have to drop and recreate all the indexes
  * and constraints that depend on the altered columns.  We do the
@@ -12306,6 +12363,22 @@ ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode)
 		add_exact_object_address(&obj, objects);
 	}
 
+	/* add dependencies for new statistics */
+	forboth(oid_item, tab->changedStatisticsOids,
+			def_item, tab->changedStatisticsDefs)
+	{
+		Oid			oldId = lfirst_oid(oid_item);
+		Oid			relid;
+
+		relid = StatisticsGetRelation(oldId, false);
+		ATPostAlterTypeParse(oldId, relid, InvalidOid,
+							 (char *) lfirst(def_item),
+							 wqueue, lockmode, tab->rewrite);
+
+		ObjectAddressSet(obj, StatisticExtRelationId, oldId);
+		add_exact_object_address(&obj, objects);
+	}
+
 	/*
 	 * Queue up command to restore replica identity index marking
 	 */
@@ -12354,9 +12427,9 @@ ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode)
 }
 
 /*
- * Parse the previously-saved definition string for a constraint or index
- * against the newly-established column data type(s), and queue up the
- * resulting command parsetrees for execution.
+ * Parse the previously-saved definition string for a constraint, index or
+ * statistics object against the newly-established column data type(s), and
+ * queue up the resulting command parsetrees for execution.
  *
  * This might fail if, for example, you have a WHERE clause that uses an
  * operator that's not available for the new column type.
@@ -12402,6 +12475,11 @@ ATPostAlterTypeParse(Oid oldId, Oid oldRelId, Oid refRelId, char *cmd,
 			querytree_list = lappend(querytree_list, stmt);
 			querytree_list = list_concat(querytree_list, afterStmts);
 		}
+		else if (IsA(stmt, CreateStatsStmt))
+			querytree_list = lappend(querytree_list,
+									 transformStatsStmt(oldRelId,
+														(CreateStatsStmt *) stmt,
+														cmd));
 		else
 			querytree_list = lappend(querytree_list, stmt);
 	}
@@ -12540,6 +12618,20 @@ ATPostAlterTypeParse(Oid oldId, Oid oldRelId, Oid refRelId, char *cmd,
 				elog(ERROR, "unexpected statement subtype: %d",
 					 (int) stmt->subtype);
 		}
+		else if (IsA(stm, CreateStatsStmt))
+		{
+			CreateStatsStmt  *stmt = (CreateStatsStmt *) stm;
+			AlterTableCmd *newcmd;
+
+			/* keep the statistics object's comment */
+			stmt->stxcomment = GetComment(oldId, StatisticExtRelationId, 0);
+
+			newcmd = makeNode(AlterTableCmd);
+			newcmd->subtype = AT_ReAddStatistics;
+			newcmd->def = (Node *) stmt;
+			tab->subcmds[AT_PASS_MISC] =
+				lappend(tab->subcmds[AT_PASS_MISC], newcmd);
+		}
 		else
 			elog(ERROR, "unexpected statement type: %d",
 				 (int) nodeTag(stm));