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left join in cursor
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* left join in cursor
@ 2003-06-09 14:21 Alexey Dashevsky <alex@kpgaz.chernigov.ua>
  2003-06-10 13:35 ` Re: left join in cursor Tom Lane <tgl@sss.pgh.pa.us>
  0 siblings, 1 reply; 2+ messages in thread

From: Alexey Dashevsky @ 2003-06-09 14:21 UTC (permalink / raw)
  To: pgsql-sql

Hi.

Exists too tables (PostgreSQL 7.2.3):

a ("cl" integer primary key, a1, a2, ...) - 100000 records;

b ("cl" integer primary key, b1, b2, ...) - 800 records.

BEGIN;

DECLARE "c" SCROLL CURSOR FOR select a.*,r.b1 as rb1 from a left join b using 
(cl) order by a.cl;

FETCH FORWARD 100 in "c"; 

FETCH FORWARD 100 in "c";

MOVE -200 in "c";

NOTICE:  Message from PostgreSQL backend:
	The Postmaster has informed me that some other backend
	died abnormally and possibly corrupted shared memory.
	I have rolled back the current transaction and am
	going to terminate your database system connection and exit.
	Please reconnect to the database system and repeat your query.

Without left join - all rights.

Why?

Thanks in advance.



^ permalink  raw  reply  [nested|flat] 2+ messages in thread

* Re: left join in cursor
  2003-06-09 14:21 left join in cursor Alexey Dashevsky <alex@kpgaz.chernigov.ua>
@ 2003-06-10 13:35 ` Tom Lane <tgl@sss.pgh.pa.us>
  0 siblings, 0 replies; 2+ messages in thread

From: Tom Lane @ 2003-06-10 13:35 UTC (permalink / raw)
  To: Alexey Dashevsky <alex@kpgaz.chernigov.ua>; +Cc: pgsql-sql

Alexey Dashevsky <alex@kpgaz.chernigov.ua> writes:
> DECLARE "c" SCROLL CURSOR FOR select a.*,r.b1 as rb1 from a left join b using
> (cl) order by a.cl;
> FETCH FORWARD 100 in "c"; 
> FETCH FORWARD 100 in "c";
> MOVE -200 in "c";
> [ core dump ]

Some plan node types don't cope very well with being run backwards.

There is a workaround for this in CVS tip, but not in 7.2.* nor (IIRC)
in 7.3.*.

			regards, tom lane



^ permalink  raw  reply  [nested|flat] 2+ messages in thread


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2003-06-09 14:21 left join in cursor Alexey Dashevsky <alex@kpgaz.chernigov.ua>
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