From 47b37a6bfaa073076c8607cdd4f65ddd569aaefa Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Thu, 22 Aug 2002 04:51:06 +0000
Subject: [PATCH] # Disallow TRUNCATE on tables that are involved in
referential constraints
The issue with finding and removing foreign key constraints is no longer
an issue, so please apply the attached.
It does NOT check for rules or on delete triggers (old style foreign
keys) as those are difficult to deal with (remove, truncate, re-add).
Rod Taylor
---
src/backend/commands/tablecmds.c | 36 +++++++++++++++++++++++-
src/test/regress/expected/truncate.out | 38 ++++++++++++++++++++++++++
src/test/regress/parallel_schedule | 2 +-
src/test/regress/serial_schedule | 3 +-
src/test/regress/sql/truncate.sql | 17 ++++++++++++
5 files changed, 93 insertions(+), 3 deletions(-)
create mode 100644 src/test/regress/expected/truncate.out
create mode 100644 src/test/regress/sql/truncate.sql
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index c6e8d686d41..1961ca1344a 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.30 2002/08/19 15:08:46 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.31 2002/08/22 04:51:05 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -332,6 +332,10 @@ TruncateRelation(const RangeVar *relation)
{
Relation rel;
Oid relid;
+ ScanKeyData key;
+ Relation fkeyRel;
+ SysScanDesc fkeyScan;
+ HeapTuple tuple;
/* Grab exclusive lock in preparation for truncate */
rel = heap_openrv(relation, AccessExclusiveLock);
@@ -356,6 +360,36 @@ TruncateRelation(const RangeVar *relation)
if (!pg_class_ownercheck(relid, GetUserId()))
aclcheck_error(ACLCHECK_NOT_OWNER, RelationGetRelationName(rel));
+ /*
+ * Don't allow truncate on tables which are referenced
+ * by foreign keys
+ */
+ fkeyRel = heap_openr(ConstraintRelationName, AccessShareLock);
+
+ ScanKeyEntryInitialize(&key, 0,
+ Anum_pg_constraint_confrelid,
+ F_OIDEQ,
+ ObjectIdGetDatum(relid));
+
+ fkeyScan = systable_beginscan(fkeyRel, 0, false,
+ SnapshotNow, 1, &key);
+
+ /*
+ * First foriegn key found with us as the reference
+ * should throw an error.
+ */
+ while (HeapTupleIsValid(tuple = systable_getnext(fkeyScan)))
+ {
+ Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
+
+ if (con->contype == 'f')
+ elog(ERROR, "TRUNCATE cannot be used as other tables reference this one via foreign key constraint %s",
+ NameStr(con->conname));
+ }
+
+ systable_endscan(fkeyScan);
+ heap_close(fkeyRel, AccessShareLock);
+
/* Keep the lock until transaction commit */
heap_close(rel, NoLock);
diff --git a/src/test/regress/expected/truncate.out b/src/test/regress/expected/truncate.out
new file mode 100644
index 00000000000..19300f63a36
--- /dev/null
+++ b/src/test/regress/expected/truncate.out
@@ -0,0 +1,38 @@
+-- Test basic TRUNCATE functionality.
+CREATE TABLE truncate_a (col1 integer primary key);
+NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index 'truncate_a_pkey' for table 'truncate_a'
+INSERT INTO truncate_a VALUES (1);
+INSERT INTO truncate_a VALUES (2);
+SELECT * FROM truncate_a;
+ col1
+------
+ 1
+ 2
+(2 rows)
+
+TRUNCATE truncate_a;
+SELECT * FROM truncate_a;
+ col1
+------
+(0 rows)
+
+-- Test foreign constraint check
+CREATE TABLE truncate_b(col1 integer references truncate_a);
+NOTICE: CREATE TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
+INSERT INTO truncate_a VALUES (1);
+SELECT * FROM truncate_a;
+ col1
+------
+ 1
+(1 row)
+
+TRUNCATE truncate_a;
+ERROR: TRUNCATE cannot be used as other tables reference this one via foreign key constraint $1
+SELECT * FROM truncate_a;
+ col1
+------
+ 1
+(1 row)
+
+DROP TABLE truncate_b;
+DROP TABLE truncate_a;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 0ac26307063..e82d9421679 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -74,4 +74,4 @@ test: select_views alter_table portals_p2 rules foreign_key cluster
# The sixth group of parallel test
# ----------
# "plpgsql" cannot run concurrently with "rules"
-test: limit plpgsql temp domain rangefuncs copy2 conversion without_oid
+test: limit plpgsql temp domain rangefuncs copy2 conversion without_oid truncate
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index d7a6deed2c9..553df2dfe7d 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -1,4 +1,4 @@
-# $Header: /cvsroot/pgsql/src/test/regress/serial_schedule,v 1.15 2002/08/11 02:06:32 tgl Exp $
+# $Header: /cvsroot/pgsql/src/test/regress/serial_schedule,v 1.16 2002/08/22 04:51:06 momjian Exp $
# This should probably be in an order similar to parallel_schedule.
test: boolean
test: char
@@ -88,3 +88,4 @@ test: domain
test: rangefuncs
test: without_oid
test: conversion
+test: truncate
diff --git a/src/test/regress/sql/truncate.sql b/src/test/regress/sql/truncate.sql
new file mode 100644
index 00000000000..5333113a9e7
--- /dev/null
+++ b/src/test/regress/sql/truncate.sql
@@ -0,0 +1,17 @@
+-- Test basic TRUNCATE functionality.
+CREATE TABLE truncate_a (col1 integer primary key);
+INSERT INTO truncate_a VALUES (1);
+INSERT INTO truncate_a VALUES (2);
+SELECT * FROM truncate_a;
+TRUNCATE truncate_a;
+SELECT * FROM truncate_a;
+
+-- Test foreign constraint check
+CREATE TABLE truncate_b(col1 integer references truncate_a);
+INSERT INTO truncate_a VALUES (1);
+SELECT * FROM truncate_a;
+TRUNCATE truncate_a;
+SELECT * FROM truncate_a;
+
+DROP TABLE truncate_b;
+DROP TABLE truncate_a;
--
GitLab