From: | "Etsuro Fujita" <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp> |
---|---|
To: | <pgsql-hackers(at)postgresql(dot)org> |
Subject: | not null validation option in contrib/file_fdw |
Date: | 2012-04-13 07:59:23 |
Message-ID: | 001901cd194b$56b50d40$041f27c0$@lab.ntt.co.jp |
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Lists: | pgsql-hackers |
I updated the patch added to CF 2012-Next [1]. Attached is the updated
version of the patch.
For the discussion in [2], I've introduced a new generic option, validate
for file_fdw foreign tables, which specifies if file_fdw verifies that
tuples meet NOT NULL constraints. The default value for the option is
'false', and if the value is set to 'true', then file_fdw verifies NOT NULL
constraints. For example, a user can issue the following to let file_fdw
verify the constraint of the msg column.
CREATE FOREIGN TABLE ft (id INTEGER, msg TEXT NOT NULL)
SERVER fs
OPTIONS (filename '/path/to/file', format 'csv',
delimiter ',', validate 'true');
At the SELECT time, ABORT is issued when a NOT NULL violation error has been
found, like COPY FROM. Once the validation is done successfully using e.g.
SELECT COUNT(*), the user can set the option to 'false' using ALTER FOREIGN
TABLE. I think this option is needed for flat files due to their lack of
ability to check such a constraint.
(I added NOT NULL checking to ileIterateForeignScan(), but not to
file_acquire_sample_rows(). Should we do that at
file_acquire_sample_rows()? I think it is good to just recommend that users
do ANALYZE a foreign table after the validation.)
For the discussion in [3], I've added a new external function
ExecNotNullCheck() and call it from fileIterateForeignScan.
Any comments are welcome.
Best regards,
Etsuro Fujita
[1] https://commitfest.postgresql.org/action/patch_view?id=822
[2] http://archives.postgresql.org/message-id/1038.1331738954@sss.pgh.pa.us
[3] http://archives.postgresql.org/pgsql-hackers/2012-03/msg00809.php
Attachment | Content-Type | Size |
---|---|---|
file_fdw_notnull_v2.patch | application/octet-stream | 10.6 KB |
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