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Re: BUG #2106: EXPLAIN ANALYZE with SELECT query causes a single backend server process to segfault

From: Michael Fuhr <mike(at)fuhr(dot)org>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: bugrep(at)oldanygroup(dot)cz, pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #2106: EXPLAIN ANALYZE with SELECT query causes a single backend server process to segfault
Date: 2005-12-10 18:41:59
Message-ID: 20051210184159.GA60282@winnie.fuhr.org (view raw or flat)
Thread:
Lists: pgsql-bugs
On Sat, Dec 10, 2005 at 12:57:13PM -0500, Tom Lane wrote:
> "" <bugrep(at)oldanygroup(dot)cz> writes:
> > Description:        EXPLAIN ANALYZE with SELECT query causes a single
> > backend server process to segfault
> 
> Could you provide a self-contained test case, please?

Here's a test case:

CREATE TABLE foo (x integer);

EXPLAIN
SELECT CASE x = 1 WHEN true THEN 1 ELSE 0 END AS y
FROM foo
ORDER BY y;

I get a segfault in 8.1.1 with EXPLAIN but not for the query alone.
Here's the stack trace:

#0  0x081bfdcf in get_rule_expr (node=0x83ac460, context=0xbfbfd4b0, showimplicit=80 'P') at pg_list.h:82
#1  0x081c0e73 in deparse_expression_pretty (expr=0x83ac460, dpcontext=0x83ac7b0, forceprefix=0 '\0', showimplicit=1 '\001', prettyFlags=32, startIndent=32)
    at ruleutils.c:1388
#2  0x080ef4a5 in explain_outNode (str=0x83ac648, plan=0x83ac388, planstate=0x83ad1f0, outer_plan=0x0, indent=0, es=0x83ac638) at explain.c:1160
#3  0x080ef90d in ExplainOnePlan (queryDesc=0x83ac5f0, stmt=0x835b708, tstate=0x8305b00) at explain.c:282
#4  0x080efca5 in ExplainOneQuery (query=0x83c7580, stmt=0x835b708, tstate=0x8305b00) at explain.c:214
#5  0x080efdcd in ExplainQuery (stmt=0x835b708, dest=0x83c7530) at explain.c:121
#6  0x0818cb2f in PortalRunUtility (portal=0x83ca018, query=0x835b228, dest=0x83c7530, completionTag=0x0) at pquery.c:987
#7  0x0818ce16 in PortalRun (portal=0x83ca018, count=2147483647, dest=0x835b748, altdest=0x835b748, completionTag=0xbfbfd7b0 "") at pg_list.h:81
#8  0x08189127 in exec_simple_query (query_string=0x835b018 "EXPLAIN\nSELECT CASE x = 1 WHEN true THEN 1 ELSE 0 END AS y\nFROM foo\nORDER BY y;") at postgres.c:1002
#9  0x0818b693 in PostgresMain (argc=4, argv=0x82e4d98, username=0x82e4d78 "mfuhr") at postgres.c:3168
#10 0x081684e6 in ServerLoop () at postmaster.c:2853
#11 0x08169a01 in PostmasterMain (argc=3, argv=0xbfbfecb8) at postmaster.c:943
#12 0x08133612 in main (argc=3, argv=0xbfbfecb8) at main.c:256

-- 
Michael Fuhr

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Next:From: Tom LaneDate: 2005-12-10 18:46:57
Subject: Re: BUG #2106: EXPLAIN ANALYZE with SELECT query causes a single backend server process to segfault
Previous:From: Bruno Wolff IIIDate: 2005-12-10 18:39:12
Subject: Re: BUG #2105: ERROR: relation "comoma" does not exist

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