9.1rc1: TRAP: FailedAssertion("!(item_width > 0)", File: "costsize.c", Line: 3274)
I am developing against 9.1beta3 and encountered this problem. I repeated it against rc1 (or
actually, REL9_1_STABLE taken from git today).
The below SQL causes:
TRAP: FailedAssertion("!(item_width > 0)", File: "costsize.c", Line: 3274)
and the session crashes.
select *
from (
select
col1
, col2
, reviewed
from
(values
( 1111, 'aweyu', 3)
, ( 2222, 'bwetu', 2)
, ( 3333, 'vwxyz', 1)
)
as r(col1,col2,col3)
left join (
select 1 as reviewed, c2 from ( values ('abcde') ) as t1(c2)
union all select 0 as reviewed, c2 from ( values ('vwxyz') ) as t2(c2)
)
as up_all on up_all.c2 = r.col2
order by col3
)
as f
;
To simplify I used 'values' for the actual tables that I am using, but the above still causes the
FailedAssertion.
Removing the outer select avoids the error and
removing order by avoids the error
Erik Rijkers
On Mon, Aug 22, 2011 at 4:16 PM, Erik Rijkers <er@xs4all.nl> wrote:
I am developing against 9.1beta3 and encountered this problem. I repeated it against rc1 (or
actually, REL9_1_STABLE taken from git today).The below SQL causes:
TRAP: FailedAssertion("!(item_width > 0)", File: "costsize.c", Line: 3274)
and the session crashes.
select *
from (
select
col1
, col2
, reviewed
from
(values
( 1111, 'aweyu', 3)
, ( 2222, 'bwetu', 2)
, ( 3333, 'vwxyz', 1)
)
as r(col1,col2,col3)
left join (
select 1 as reviewed, c2 from ( values ('abcde') ) as t1(c2)
union all select 0 as reviewed, c2 from ( values ('vwxyz') ) as t2(c2)
)
as up_all on up_all.c2 = r.col2
order by col3
)
as f
;To simplify I used 'values' for the actual tables that I am using, but the above still causes the
FailedAssertion.Removing the outer select avoids the error and
removing order by avoids the error
I can reproduce this on master but not on 9.0. I suspect the problem
was introduced by this commit:
commit 0f61d4dd1b4f95832dcd81c9688dac56fd6b5687
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri Nov 19 17:31:50 2010 -0500
Improve relation width estimation for subqueries.
...but I haven't confirmed that yet.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
Robert Haas <robertmhaas@gmail.com> writes:
On Mon, Aug 22, 2011 at 4:16 PM, Erik Rijkers <er@xs4all.nl> wrote:
The below SQL causes:
TRAP: FailedAssertion("!(item_width > 0)", File: "costsize.c", Line: 3274)
I can reproduce this on master but not on 9.0. I suspect the problem
was introduced by this commit:
commit 0f61d4dd1b4f95832dcd81c9688dac56fd6b5687
Well, that's a pretty safe bet considering the Assert is in code that
didn't exist before that commit ;-). The question is why the per-column
width estimate hasn't been set for that column. Looking at the
coredump, I see that the width *did* get set for the subquery's other
output column, which makes it even weirder. Too tired to dig further
right now though.
regards, tom lane