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postgres_fdw: Account for triggers in non-direct remote UPDATE planning.

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Previously, in postgresPlanForeignModify, we planned an UPDATE operation
on a foreign table so that we transmit only columns that were explicitly
targets of the UPDATE, so as to avoid unnecessary data transmission, but
if there were BEFORE ROW UPDATE triggers on the foreign table, those
triggers might change values for non-target columns, in which case we
would miss sending changed values for those columns.  Prevent optimizing
away transmitting all columns if there are BEFORE ROW UPDATE triggers on
the foreign table.

This is an oversight in commit 7cbe57c34 which added triggers on foreign
tables, so apply the patch all the way back to 9.4 where that came in.

Author: Shohei Mochizuki
Reviewed-by: Amit Langote
Discussion: https://postgr.es/m/201905270152.x4R1q3qi014550@toshiba.co.jp
This commit is contained in:
Etsuro Fujita
2019-06-13 17:59:13 +09:00
parent 457dab1e7b
commit 1ade21e7fa
3 changed files with 43 additions and 12 deletions
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5
contrib/postgres_fdw/sql/postgres_fdw.sql
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@ -1065,6 +1065,11 @@ SELECT * from loc1;
UPDATE rem1 set f2 = 'skidoo' RETURNING f2;
SELECT * from loc1;
EXPLAIN (verbose, costs off)
UPDATE rem1 set f1 = 10; -- all columns should be transmitted
UPDATE rem1 set f1 = 10;
SELECT * from loc1;
DELETE FROM rem1;
-- Add a second trigger, to check that the changes are propagated correctly