From 4deb57de7dcfb66f850f16c0324731fdf3d86d09 Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Sat, 26 Jan 2013 13:33:24 -0500
Subject: [PATCH] Issue ERROR if FREEZE mode can't be honored by COPY
Previously non-honored FREEZE mode was ignored. This also issues an
appropriate error message based on the cause of the failure, per
suggestion from Tom. Additional regression test case added.
---
doc/src/sgml/ref/copy.sgml | 12 ++++-------
src/backend/commands/copy.c | 32 ++++++++++++++++++-----------
src/test/regress/expected/copy2.out | 18 ++++++++--------
src/test/regress/sql/copy2.sql | 9 +++++++-
4 files changed, 40 insertions(+), 31 deletions(-)
diff --git a/doc/src/sgml/ref/copy.sgml b/doc/src/sgml/ref/copy.sgml
index 6a0fabc978d..2137c67cb4b 100644
--- a/doc/src/sgml/ref/copy.sgml
+++ b/doc/src/sgml/ref/copy.sgml
@@ -190,18 +190,14 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
would be after running the <command>VACUUM FREEZE</> command.
This is intended as a performance option for initial data loading.
Rows will be frozen only if the table being loaded has been created
- in the current subtransaction, there are no cursors open and there
- are no older snapshots held by this transaction. If those conditions
- are not met the command will continue without error though will not
- freeze rows. It is also possible in rare cases that the request
- cannot be honoured for internal reasons, hence <literal>FREEZE</literal>
- is more of a guideline than a hard rule.
+ or truncated in the current subtransaction, there are no cursors
+ open and there are no older snapshots held by this transaction.
</para>
<para>
Note that all other sessions will immediately be able to see the data
once it has been successfully loaded. This violates the normal rules
- of MVCC visibility and by specifying this option the user acknowledges
- explicitly that this is understood.
+ of MVCC visibility and users specifying should be aware of the
+ potential problems this might cause.
</para>
</listitem>
</varlistentry>
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 8778e8b15c3..49cc8dd88f4 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -1978,8 +1978,6 @@ CopyFrom(CopyState cstate)
* ROLLBACK TO save;
* COPY ...
*
- * However this is OK since at worst we will fail to make the optimization.
- *
* Also, if the target file is new-in-transaction, we assume that checking
* FSM for free space is a waste of time, even if we must use WAL because
* of archiving. This could possibly be wrong, but it's unlikely.
@@ -1991,6 +1989,7 @@ CopyFrom(CopyState cstate)
* no additional work to enforce that.
*----------
*/
+ /* createSubid is creation check, newRelfilenodeSubid is truncation check */
if (cstate->rel->rd_createSubid != InvalidSubTransactionId ||
cstate->rel->rd_newRelfilenodeSubid != InvalidSubTransactionId)
{
@@ -2006,18 +2005,27 @@ CopyFrom(CopyState cstate)
* after xact cleanup. Note that the stronger test of exactly
* which subtransaction created it is crucial for correctness
* of this optimisation.
- *
- * As noted above rd_newRelfilenodeSubid is not set in all cases
- * where we can apply the optimization, so in those rare cases
- * where we cannot honour the request we do so silently.
*/
- if (cstate->freeze &&
- ThereAreNoPriorRegisteredSnapshots() &&
- ThereAreNoReadyPortals() &&
- (cstate->rel->rd_newRelfilenodeSubid == GetCurrentSubTransactionId() ||
- cstate->rel->rd_createSubid == GetCurrentSubTransactionId()))
- hi_options |= HEAP_INSERT_FROZEN;
+ if (cstate->freeze)
+ {
+ if (!ThereAreNoPriorRegisteredSnapshots() || !ThereAreNoReadyPortals())
+ ereport(ERROR,
+ (ERRCODE_INVALID_TRANSACTION_STATE,
+ errmsg("cannot perform FREEZE because of prior transaction activity")));
+
+ if (cstate->rel->rd_createSubid == GetCurrentSubTransactionId() ||
+ cstate->rel->rd_newRelfilenodeSubid == GetCurrentSubTransactionId())
+ hi_options |= HEAP_INSERT_FROZEN;
+ else
+ ereport(ERROR,
+ (ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE,
+ errmsg("cannot perform FREEZE because of transaction activity after table creation or truncation")));
+ }
}
+ else if (cstate->freeze)
+ ereport(ERROR,
+ (ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE,
+ errmsg("cannot perform FREEZE because the table was not created or truncated in the current transaction")));
/*
* We need a ResultRelInfo so we can use the regular executor's
diff --git a/src/test/regress/expected/copy2.out b/src/test/regress/expected/copy2.out
index 78c601fd9ba..5777b242747 100644
--- a/src/test/regress/expected/copy2.out
+++ b/src/test/regress/expected/copy2.out
@@ -334,22 +334,20 @@ SELECT * FROM vistest;
COMMIT;
TRUNCATE vistest;
COPY vistest FROM stdin CSV FREEZE;
+ERROR: cannot perform FREEZE because the table was not created or truncated in the current transaction
+BEGIN;
+TRUNCATE vistest;
+SAVEPOINT s1;
+COPY vistest FROM stdin CSV FREEZE;
+ERROR: cannot perform FREEZE because of transaction activity after table creation or truncation
+COMMIT;
BEGIN;
INSERT INTO vistest VALUES ('z');
SAVEPOINT s1;
TRUNCATE vistest;
ROLLBACK TO SAVEPOINT s1;
COPY vistest FROM stdin CSV FREEZE;
-SELECT * FROM vistest;
- a
-----
- p
- g
- z
- d3
- e
-(5 rows)
-
+ERROR: cannot perform FREEZE because the table was not created or truncated in the current transaction
COMMIT;
CREATE FUNCTION truncate_in_subxact() RETURNS VOID AS
$$
diff --git a/src/test/regress/sql/copy2.sql b/src/test/regress/sql/copy2.sql
index 55568e68e40..c46128b38a1 100644
--- a/src/test/regress/sql/copy2.sql
+++ b/src/test/regress/sql/copy2.sql
@@ -234,6 +234,14 @@ p
g
\.
BEGIN;
+TRUNCATE vistest;
+SAVEPOINT s1;
+COPY vistest FROM stdin CSV FREEZE;
+m
+k
+\.
+COMMIT;
+BEGIN;
INSERT INTO vistest VALUES ('z');
SAVEPOINT s1;
TRUNCATE vistest;
@@ -242,7 +250,6 @@ COPY vistest FROM stdin CSV FREEZE;
d3
e
\.
-SELECT * FROM vistest;
COMMIT;
CREATE FUNCTION truncate_in_subxact() RETURNS VOID AS
$$
--
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