From 5f9b05ada1bb4b5576944227a2d330cde29683cb Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 1 Dec 2020 14:02:28 -0500 Subject: [PATCH] Ensure that expandTableLikeClause() re-examines the same table. As it stood, expandTableLikeClause() re-did the same relation_openrv call that transformTableLikeClause() had done. However there are scenarios where this would not find the same table as expected. We hold lock on the LIKE source table, so it can't be renamed or dropped, but another table could appear before it in the search path. This explains the odd behavior reported in bug #16758 when cloning a table as a temp table of the same name. This case worked as expected before commit 502898192 introduced the need to open the source table twice, so we should fix it. To make really sure we get the same table, let's re-open it by OID not name. That requires adding an OID field to struct TableLikeClause, which is a little nervous-making from an ABI standpoint, but as long as it's at the end I don't think there's any serious risk. Per bug #16758 from Marc Boeren. Like the previous patch, back-patch to all supported branches. Discussion: https://postgr.es/m/16758-840e84a6cfab276d@postgresql.org --- src/backend/nodes/copyfuncs.c | 1 + src/backend/nodes/equalfuncs.c | 1 + src/backend/nodes/outfuncs.c | 1 + src/backend/parser/gram.y | 1 + src/backend/parser/parse_utilcmd.c | 14 ++++++++++--- src/include/nodes/parsenodes.h | 1 + .../regress/expected/create_table_like.out | 21 +++++++++++++++++++ src/test/regress/sql/create_table_like.sql | 8 +++++++ 8 files changed, 45 insertions(+), 3 deletions(-) diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c index b4a597bb83c..a0ef3ff1407 100644 --- a/src/backend/nodes/copyfuncs.c +++ b/src/backend/nodes/copyfuncs.c @@ -3368,6 +3368,7 @@ _copyTableLikeClause(const TableLikeClause *from) COPY_NODE_FIELD(relation); COPY_SCALAR_FIELD(options); + COPY_SCALAR_FIELD(relationOid); return newnode; } diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c index 4f2ebe5118e..88e17a3a604 100644 --- a/src/backend/nodes/equalfuncs.c +++ b/src/backend/nodes/equalfuncs.c @@ -1252,6 +1252,7 @@ _equalTableLikeClause(const TableLikeClause *a, const TableLikeClause *b) { COMPARE_NODE_FIELD(relation); COMPARE_SCALAR_FIELD(options); + COMPARE_SCALAR_FIELD(relationOid); return true; } diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c index fc75384c07b..4a0e461d366 100644 --- a/src/backend/nodes/outfuncs.c +++ b/src/backend/nodes/outfuncs.c @@ -2746,6 +2746,7 @@ _outTableLikeClause(StringInfo str, const TableLikeClause *node) WRITE_NODE_FIELD(relation); WRITE_UINT_FIELD(options); + WRITE_OID_FIELD(relationOid); } static void diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y index 32797728d2e..9de9dbd8a8a 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -3595,6 +3595,7 @@ TableLikeClause: TableLikeClause *n = makeNode(TableLikeClause); n->relation = $2; n->options = $3; + n->relationOid = InvalidOid; $$ = (Node *)n; } ; diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c index d3ef6f4ab58..577fe1e752e 100644 --- a/src/backend/parser/parse_utilcmd.c +++ b/src/backend/parser/parse_utilcmd.c @@ -1091,14 +1091,18 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla * we don't yet know what column numbers the copied columns will have in * the finished table. If any of those options are specified, add the * LIKE clause to cxt->likeclauses so that expandTableLikeClause will be - * called after we do know that. + * called after we do know that. Also, remember the relation OID so that + * expandTableLikeClause is certain to open the same table. */ if (table_like_clause->options & (CREATE_TABLE_LIKE_DEFAULTS | CREATE_TABLE_LIKE_GENERATED | CREATE_TABLE_LIKE_CONSTRAINTS | CREATE_TABLE_LIKE_INDEXES)) + { + table_like_clause->relationOid = RelationGetRelid(relation); cxt->likeclauses = lappend(cxt->likeclauses, table_like_clause); + } /* * We may copy extended statistics if requested, since the representation @@ -1171,9 +1175,13 @@ expandTableLikeClause(RangeVar *heapRel, TableLikeClause *table_like_clause) * Open the relation referenced by the LIKE clause. We should still have * the table lock obtained by transformTableLikeClause (and this'll throw * an assertion failure if not). Hence, no need to recheck privileges - * etc. + * etc. We must open the rel by OID not name, to be sure we get the same + * table. */ - relation = relation_openrv(table_like_clause->relation, NoLock); + if (!OidIsValid(table_like_clause->relationOid)) + elog(ERROR, "expandTableLikeClause called on untransformed LIKE clause"); + + relation = relation_open(table_like_clause->relationOid, NoLock); tupleDesc = RelationGetDescr(relation); constr = tupleDesc->constr; diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h index 439dfea29ad..96ad25208c0 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -671,6 +671,7 @@ typedef struct TableLikeClause NodeTag type; RangeVar *relation; bits32 options; /* OR of TableLikeOption flags */ + Oid relationOid; /* If table has been looked up, its OID */ } TableLikeClause; typedef enum TableLikeOption diff --git a/src/test/regress/expected/create_table_like.out b/src/test/regress/expected/create_table_like.out index 59acaf394df..2877436cb49 100644 --- a/src/test/regress/expected/create_table_like.out +++ b/src/test/regress/expected/create_table_like.out @@ -455,6 +455,27 @@ Statistics objects: "public"."pg_attrdef_a_b_stat" (ndistinct, dependencies, mcv) ON a, b FROM public.pg_attrdef DROP TABLE public.pg_attrdef; +-- Check that LIKE isn't confused when new table masks the old, either +BEGIN; +CREATE SCHEMA ctl_schema; +SET LOCAL search_path = ctl_schema, public; +CREATE TABLE ctlt1 (LIKE ctlt1 INCLUDING ALL); +\d+ ctlt1 + Table "ctl_schema.ctlt1" + Column | Type | Collation | Nullable | Default | Storage | Stats target | Description +--------+------+-----------+----------+---------+----------+--------------+------------- + a | text | | not null | | main | | A + b | text | | | | extended | | B +Indexes: + "ctlt1_pkey" PRIMARY KEY, btree (a) + "ctlt1_b_idx" btree (b) + "ctlt1_expr_idx" btree ((a || b)) +Check constraints: + "ctlt1_a_check" CHECK (length(a) > 2) +Statistics objects: + "ctl_schema"."ctlt1_a_b_stat" (ndistinct, dependencies, mcv) ON a, b FROM ctlt1 + +ROLLBACK; DROP TABLE ctlt1, ctlt2, ctlt3, ctlt4, ctlt12_storage, ctlt12_comments, ctlt1_inh, ctlt13_inh, ctlt13_like, ctlt_all, ctla, ctlb CASCADE; NOTICE: drop cascades to table inhe /* LIKE with other relation kinds */ diff --git a/src/test/regress/sql/create_table_like.sql b/src/test/regress/sql/create_table_like.sql index 00dff231e39..20374c8c669 100644 --- a/src/test/regress/sql/create_table_like.sql +++ b/src/test/regress/sql/create_table_like.sql @@ -173,6 +173,14 @@ CREATE TABLE pg_attrdef (LIKE ctlt1 INCLUDING ALL); \d+ public.pg_attrdef DROP TABLE public.pg_attrdef; +-- Check that LIKE isn't confused when new table masks the old, either +BEGIN; +CREATE SCHEMA ctl_schema; +SET LOCAL search_path = ctl_schema, public; +CREATE TABLE ctlt1 (LIKE ctlt1 INCLUDING ALL); +\d+ ctlt1 +ROLLBACK; + DROP TABLE ctlt1, ctlt2, ctlt3, ctlt4, ctlt12_storage, ctlt12_comments, ctlt1_inh, ctlt13_inh, ctlt13_like, ctlt_all, ctla, ctlb CASCADE;