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Add tg_updatedcols to TriggerData

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This allows a trigger function to determine for an UPDATE trigger
which columns were actually updated.  This allows some optimizations
in generic trigger functions such as lo_manage and
tsvector_update_trigger.

Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://www.postgresql.org/message-id/flat/11c5f156-67a9-0fb5-8200-2a8018eb2e0c@2ndquadrant.com
This commit is contained in:
Peter Eisentraut
2020-03-09 09:22:22 +01:00
parent 8f152b6c50
commit 71d60e2aa0
7 changed files with 68 additions and 9 deletions
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8
contrib/lo/expected/lo.out
View File

@ -36,6 +36,14 @@ SELECT lo_get(43214);
\x
(1 row)
-- test updating of unrelated column
UPDATE image SET title = 'beautiful picture' WHERE title = 'beautiful image';
SELECT lo_get(43214);
lo_get
--------
\x
(1 row)
DELETE FROM image;
SELECT lo_get(43214);
ERROR: large object 43214 does not exist

3
contrib/lo/lo.c
View File

@ -74,7 +74,8 @@ lo_manage(PG_FUNCTION_ARGS)
* Here, if the value of the monitored attribute changes, then the large
* object associated with the original value is unlinked.
*/
if (newtuple != NULL)
if (newtuple != NULL &&
bms_is_member(attnum - FirstLowInvalidHeapAttributeNumber, trigdata->tg_updatedcols))
{
char *orig = SPI_getvalue(trigtuple, tupdesc, attnum);
char *newv = SPI_getvalue(newtuple, tupdesc, attnum);

5
contrib/lo/sql/lo.sql
View File

@ -18,6 +18,11 @@ UPDATE image SET raster = 43214 WHERE title = 'beautiful image';
SELECT lo_get(43213);
SELECT lo_get(43214);
-- test updating of unrelated column
UPDATE image SET title = 'beautiful picture' WHERE title = 'beautiful image';
SELECT lo_get(43214);
DELETE FROM image;
SELECT lo_get(43214);