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Avoid some table rewrites for ALTER TABLE .. SET DATA TYPE timestamp.

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When the timezone is UTC, timestamptz and timestamp are binary coercible
in both directions.  See b8a18ad485 and
c22ecc6562 for the previous attempt in
this problem space.  Skip the table rewrite; for now, continue to
needlessly rewrite any index on an affected column.

Reviewed by Simon Riggs and Tom Lane.

Discussion: https://postgr.es/m/20190226061450.GA1665944@rfd.leadboat.com
This commit is contained in:
Noah Misch
2019-03-08 20:16:27 -08:00
parent 82a5649fb9
commit 3c5926301a
5 changed files with 65 additions and 7 deletions
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11
src/test/regress/expected/event_trigger.out
View File

@ -435,7 +435,7 @@ END;
$$;
create event trigger no_rewrite_allowed on table_rewrite
execute procedure test_evtrig_no_rewrite();
create table rewriteme (id serial primary key, foo float);
create table rewriteme (id serial primary key, foo float, bar timestamptz);
insert into rewriteme
select x * 1.001 from generate_series(1, 500) as t(x);
alter table rewriteme alter column foo type numeric;
@ -458,6 +458,15 @@ alter table rewriteme
NOTICE: Table 'rewriteme' is being rewritten (reason = 4)
-- shouldn't trigger a table_rewrite event
alter table rewriteme alter column foo type numeric(12,4);
begin;
set timezone to 'UTC';
alter table rewriteme alter column bar type timestamp;
set timezone to '0';
alter table rewriteme alter column bar type timestamptz;
set timezone to 'Europe/London';
alter table rewriteme alter column bar type timestamp; -- does rewrite
NOTICE: Table 'rewriteme' is being rewritten (reason = 4)
rollback;
-- typed tables are rewritten when their type changes. Don't emit table
-- name, because firing order is not stable.
CREATE OR REPLACE FUNCTION test_evtrig_no_rewrite() RETURNS event_trigger

10
src/test/regress/sql/event_trigger.sql
View File

@ -329,7 +329,7 @@ $$;
create event trigger no_rewrite_allowed on table_rewrite
execute procedure test_evtrig_no_rewrite();
create table rewriteme (id serial primary key, foo float);
create table rewriteme (id serial primary key, foo float, bar timestamptz);
insert into rewriteme
select x * 1.001 from generate_series(1, 500) as t(x);
alter table rewriteme alter column foo type numeric;
@ -352,6 +352,14 @@ alter table rewriteme
-- shouldn't trigger a table_rewrite event
alter table rewriteme alter column foo type numeric(12,4);
begin;
set timezone to 'UTC';
alter table rewriteme alter column bar type timestamp;
set timezone to '0';
alter table rewriteme alter column bar type timestamptz;
set timezone to 'Europe/London';
alter table rewriteme alter column bar type timestamp; -- does rewrite
rollback;
-- typed tables are rewritten when their type changes. Don't emit table
-- name, because firing order is not stable.