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Re: Bug with large results
- From: Fernando Nasser <fnasser at redhat dot com>
- To: Jeffrey Melloy <jmelloy at visualdistortion dot org>
- Cc: rhdb-explain at sources dot redhat dot com
- Date: Fri, 22 Oct 2004 09:55:54 -0400
- Subject: Re: Bug with large results
- Organization: Red Hat Canada
- References: <2CDEED12-23D1-11D9-A663-000393C79B3C@visualdistortion.org>
Hi Jeffrey,
It is not the size of the result. It happens that a new type of node
was added to the 7.4 version after we had released this version.
There is a patch, posted to this list, by Peter Eisentraut, that
provides a workaround for this (it does not add the new nodes but
prevents the NPE).
I did not incorporate it as I keep expecting someone will send a patch
that includes code for all the new nodes, or that I myself find the time
to do it. In any case, it should not throw exception if a unknown type
of node is found, just print a warning or something.
If you have problems obtaining it from the list archives or rebuilding
rhdb-explain please send me a note and I will try and help.
Regards,
Fernando
Jeffrey Melloy wrote:
I downloaded RHDB-explain (CVS) and stumbled across a bug.
Small queries work fine, but a larger plan will fail with a null
pointer exception.
Using PostgreSQL 7.4.5 on OS X.
Thanks,
Jeff
Error:
java.lang.NullPointerException
at
com.redhat.rhdb.explain.ExplainParserV73.addQual(ExplainParserV73.java:
796)
at
com.redhat.rhdb.explain.ExplainParserV73.buildExplainTree(ExplainParserV
73.java:343)
at
com.redhat.rhdb.explain.ExplainParserV73.explain(ExplainParserV73.java:
187)
at
com.redhat.rhdb.explain.Explain$ExplainThread.run(Explain.java:298)
Query:
select * from message_v;
plan:
QUERY PLAN
------------------------------------------------------------------------
-----------------------------------
Hash Join (cost=34961.26..3454046.29 rows=155607 width=164)
Hash Cond: ("outer".sender_id = "inner".user_id)
Join Filter: (("inner".effdate <= "outer".message_date) AND (NOT
(subplan)))
-> Hash Join (cost=34923.29..2628055.36 rows=50978 width=115)
Hash Cond: ("outer".recipient_id = "inner".user_id)
Join Filter: (NOT (subplan))
-> Merge Join (cost=34916.77..50555.99 rows=297841 width=105)
Merge Cond: ("outer".user_id = "inner".recipient_id)
Join Filter: ("outer".effdate <= "inner".message_date)
-> Sort (cost=46.03..47.35 rows=526 width=39)
Sort Key: r_disp.user_id
-> Seq Scan on user_display_name r_disp
(cost=0.00..22.26 rows=526 width=39)
-> Sort (cost=34870.74..35279.24 rows=163399 width=66)
Sort Key: m.recipient_id
-> Seq Scan on messages m (cost=0.00..6361.99
rows=163399 width=66)
-> Hash (cost=5.81..5.81 rows=281 width=26)
-> Seq Scan on users r (cost=0.00..5.81 rows=281
width=26)
SubPlan
-> Index Scan using im_display_user on user_display_name
udn (cost=0.00..8.64 rows=1 width=0)
Index Cond: (user_id = $4)
Filter: ((effdate > $3) AND (effdate <= $2))
-> Hash (cost=36.66..36.66 rows=526 width=65)
-> Hash Join (cost=6.51..36.66 rows=526 width=65)
Hash Cond: ("outer".user_id = "inner".user_id)
-> Seq Scan on user_display_name s_disp
(cost=0.00..22.26 rows=526 width=39)
-> Hash (cost=5.81..5.81 rows=281 width=26)
-> Seq Scan on users s (cost=0.00..5.81 rows=281
width=26)
SubPlan
-> Index Scan using im_display_user on user_display_name udn
(cost=0.00..8.64 rows=1 width=0)
Index Cond: (user_id = $1)
Filter: ((effdate > $0) AND (effdate <= $2))
(31 rows)
--
Fernando Nasser
Red Hat Canada Ltd. E-Mail: fnasser@redhat.com
2323 Yonge Street, Suite #300
Toronto, Ontario M4P 2C9