From f00c4400270f21905305a4648d1f3d57400a2e15 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 | 19 +++++++++++++++++++ src/test/regress/sql/create_table_like.sql | 8 ++++++++ 8 files changed, 43 insertions(+), 3 deletions(-) diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c index c2b1ccf99f1..fcdb7d2cdb2 100644 --- a/src/backend/nodes/copyfuncs.c +++ b/src/backend/nodes/copyfuncs.c @@ -3025,6 +3025,7 @@ _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 a7e1694e23b..1d9475965a1 100644 --- a/src/backend/nodes/equalfuncs.c +++ b/src/backend/nodes/equalfuncs.c @@ -1172,6 +1172,7 @@ _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 96cefabb8f8..b89251586bc 100644 --- a/src/backend/nodes/outfuncs.c +++ b/src/backend/nodes/outfuncs.c @@ -2541,6 +2541,7 @@ _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 6e15df231fa..31ec7d196f2 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -3174,6 +3174,7 @@ 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 57ea3fa1163..ebf9d19b874 100644 --- a/src/backend/parser/parse_utilcmd.c +++ b/src/backend/parser/parse_utilcmd.c @@ -909,12 +909,16 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla * 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. + * 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_CONSTRAINTS | CREATE_TABLE_LIKE_INDEXES)) + { + table_like_clause->relationOid = RelationGetRelid(relation); cxt->likeclauses = lappend(cxt->likeclauses, table_like_clause); + } /* * Close the parent rel, but keep our AccessShareLock on it until xact @@ -948,9 +952,13 @@ 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 e6e11142a84..4dd2d4ecfb7 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -610,6 +610,7 @@ 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 4739cd5ee3c..734319ef023 100644 --- a/src/test/regress/expected/create_table_like.out +++ b/src/test/regress/expected/create_table_like.out @@ -275,6 +275,25 @@ Check constraints: "ctlt1_a_check" CHECK (length(a) > 2) 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 | Modifiers | 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) + +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 86fa43415ed..dd0b212661f 100644 --- a/src/test/regress/sql/create_table_like.sql +++ b/src/test/regress/sql/create_table_like.sql @@ -122,6 +122,14 @@ 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;