From: | "Hou, Zhijie" <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com> |
---|---|
To: | Greg Nancarrow <gregn4422(at)gmail(dot)com> |
Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, vignesh C <vignesh21(at)gmail(dot)com>, "Amit Langote" <amitlangote09(at)gmail(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)fujitsu(dot)com>, "Tang, Haiying" <tanghy(dot)fnst(at)cn(dot)fujitsu(dot)com> |
Subject: | RE: Parallel INSERT (INTO ... SELECT ...) |
Date: | 2021-02-05 03:58:24 |
Message-ID: | eaeb347d297b4be6b2a660b89cdffb64@G08CNEXMBPEKD05.g08.fujitsu.local |
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Lists: | pgsql-hackers |
Hi,
I took a look into the hasModifyingCTE bugfix recently,
and found a possible bug case without the parallel insert patch.
---------------------------------
drop table if exists test_data1;
create table test_data1(a int, b int) ;
insert into test_data1 select generate_series(1,1000), generate_series(1,1000);
set force_parallel_mode=on;
CREATE TEMP TABLE bug6051 AS
select i from generate_series(1,3) as i;
SELECT * FROM bug6051;
CREATE RULE bug6051_ins AS ON INSERT TO bug6051 DO INSTEAD select a as i from test_data1;
WITH t1 AS ( DELETE FROM bug6051 RETURNING * ) INSERT INTO bug6051 SELECT * FROM t1;
*******
***ERROR: cannot assign XIDs during a parallel operation
*******
---------------------------------
I debugged it and it did have modifycte in the parsetree after rewrite.
I think if we can properly set the hasModifyingCTE, we can avoid this error by not consider parallel for this.
Thoughts ?
Best regards,
houzj
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