database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-27 12:41:57 +03:00
Code Activity

Fix contrib/dblink to handle inconsistent DateStyle/IntervalStyle safely.

Browse Source 
If the remote database's settings of these GUCs are different from ours,
ambiguous datetime values may be read incorrectly.  To fix, temporarily
adopt the remote server's settings while we ingest a query result.

This is not a complete fix, since it doesn't do anything about ambiguous
values in commands sent to the remote server; but there seems little we
can do about that end of it given dblink's entirely textual API for
transmitted commands.

Back-patch to 9.2.  The hazard exists in all versions, but this patch
would need more work to apply before 9.2.  Given the lack of field
complaints about this issue, it doesn't seem worth the effort at present.

Daniel Farina and Tom Lane
This commit is contained in:
Tom Lane
2013-03-22 15:22:15 -04:00
parent 549dae0352
commit 8a3b6772ae
3 changed files with 372 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

96
contrib/dblink/sql/dblink.sql
View File

@ -426,3 +426,99 @@ SELECT dblink_build_sql_update('test_dropped', '1', 1,
SELECT dblink_build_sql_delete('test_dropped', '1', 1,
ARRAY['2'::TEXT]);
-- test local mimicry of remote GUC values that affect datatype I/O
SET datestyle = ISO, MDY;
SET intervalstyle = postgres;
SET timezone = UTC;
SELECT dblink_connect('myconn','dbname=contrib_regression');
SELECT dblink_exec('myconn', 'SET datestyle = GERMAN, DMY;');
-- single row synchronous case
SELECT *
FROM dblink('myconn',
'SELECT * FROM (VALUES (''12.03.2013 00:00:00+00'')) t')
AS t(a timestamptz);
-- multi-row synchronous case
SELECT *
FROM dblink('myconn',
'SELECT * FROM
(VALUES (''12.03.2013 00:00:00+00''),
(''12.03.2013 00:00:00+00'')) t')
AS t(a timestamptz);
-- single-row asynchronous case
SELECT *
FROM dblink_send_query('myconn',
'SELECT * FROM
(VALUES (''12.03.2013 00:00:00+00'')) t');
CREATE TEMPORARY TABLE result AS
(SELECT * from dblink_get_result('myconn') as t(t timestamptz))
UNION ALL
(SELECT * from dblink_get_result('myconn') as t(t timestamptz));
SELECT * FROM result;
DROP TABLE result;
-- multi-row asynchronous case
SELECT *
FROM dblink_send_query('myconn',
'SELECT * FROM
(VALUES (''12.03.2013 00:00:00+00''),
(''12.03.2013 00:00:00+00'')) t');
CREATE TEMPORARY TABLE result AS
(SELECT * from dblink_get_result('myconn') as t(t timestamptz))
UNION ALL
(SELECT * from dblink_get_result('myconn') as t(t timestamptz))
UNION ALL
(SELECT * from dblink_get_result('myconn') as t(t timestamptz));
SELECT * FROM result;
DROP TABLE result;
-- Try an ambiguous interval
SELECT dblink_exec('myconn', 'SET intervalstyle = sql_standard;');
SELECT *
FROM dblink('myconn',
'SELECT * FROM (VALUES (''-1 2:03:04'')) i')
AS i(i interval);
-- Try swapping to another format to ensure the GUCs are tracked
-- properly through a change.
CREATE TEMPORARY TABLE result (t timestamptz);
SELECT dblink_exec('myconn', 'SET datestyle = ISO, MDY;');
INSERT INTO result
SELECT *
FROM dblink('myconn',
'SELECT * FROM (VALUES (''03.12.2013 00:00:00+00'')) t')
AS t(a timestamptz);
SELECT dblink_exec('myconn', 'SET datestyle = GERMAN, DMY;');
INSERT INTO result
SELECT *
FROM dblink('myconn',
'SELECT * FROM (VALUES (''12.03.2013 00:00:00+00'')) t')
AS t(a timestamptz);
SELECT * FROM result;
DROP TABLE result;
-- Check error throwing in dblink_fetch
SELECT dblink_open('myconn','error_cursor',
'SELECT * FROM (VALUES (''1''), (''not an int'')) AS t(text);');
SELECT *
FROM dblink_fetch('myconn','error_cursor', 1) AS t(i int);
SELECT *
FROM dblink_fetch('myconn','error_cursor', 1) AS t(i int);
-- Make sure that the local settings have retained their values in spite
-- of shenanigans on the connection.
SHOW datestyle;
SHOW intervalstyle;
-- Clean up GUC-setting tests
SELECT dblink_disconnect('myconn');
RESET datestyle;
RESET intervalstyle;
RESET timezone;