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Re: Bug with large results


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


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