From c2793d9200948d693150a5bbeb3815e3b5404be2 Mon Sep 17 00:00:00 2001 From: Kyotaro Horiguchi Date: Tue, 12 Dec 2017 17:38:12 +0900 Subject: [PATCH 2/2] Lock parent on ALTER TABLE NO INHERIT NO INHERIT doesn't modify the parent at all but lock is required to avoid error caused when a concurrent access see a false child. --- src/backend/commands/tablecmds.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index d979ce2..a8d119f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -13246,7 +13246,28 @@ RangeVarCallbackForAlterRelation(const RangeVar *rv, Oid relid, Oid oldrelid, reltype = ((AlterObjectSchemaStmt *) stmt)->objectType; else if (IsA(stmt, AlterTableStmt)) - reltype = ((AlterTableStmt *) stmt)->relkind; + { + AlterTableStmt *alterstmt = (AlterTableStmt *)stmt; + ListCell *lc; + + reltype = alterstmt->relkind; + + foreach (lc, alterstmt->cmds) + { + AlterTableCmd *cmd = lfirst_node(AlterTableCmd, lc); + Assert(IsA(cmd, AlterTableCmd)); + + /* + * Though NO INHERIT doesn't modify the parent, lock on the parent + * is necessary so that no concurrent expansion of inheritances + * sees a false child and ends with ERROR. But no need to ascend + * further. + */ + if (cmd->subtype == AT_DropInherit) + RangeVarGetRelid((RangeVar *)cmd->def, + AccessExclusiveLock, false); + } + } else { reltype = OBJECT_TABLE; /* placate compiler */ -- 2.9.2