performance issue

From: Steven varga <varga(at)yorku(dot)ca>
To: pgsql-jdbc(at)postgresql(dot)org
Subject: performance issue
Date: 2008-03-27 04:46:03
Message-ID: Pine.LNX.4.64.0803262321270.18973@localhost
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hi,

having about 10^6 records in a table indexed on names (http://www.upcdatabase.com)
and doing a query from psql I get response time in millisec order on the
other hand when executing the same query through JDBC it hangs about 80
seconds.
This is about 10^5 decrease in speed.

After profiling the JDBC driver simply waits for data
PGStream.ReceiveChar() spending enough time to do a sequencial scan on all
10^6 records.

Can anyone give a suggestion why is this lag?

PSQL:

test=# EXPLAIN ANALYZE SELECT count(*) from upc where name like 'Aba%';
QUERY PLAN
Aggregate (cost=14897.01..14897.02 rows=1 width=0) (actual
time=0.380..0.381 rows=1 loops=1)
-> Bitmap Heap Scan on upc (cost=57.67..14885.47 rows=4612
width=0) (actual time=0.216..0.326 rows=13 loops=1)
Filter: ((name)::text ~~ 'Aba%'::text)
-> Bitmap Index Scan on upc_name (cost=0.00..57.67
rows=4612 width=0) (actual time=0.155..0.155 rows=13 loops=1)
Index Cond: (((name)::text >= 'Aba'::character varying) AND
((name)::text < 'Abb'::character varying))
Total runtime: 0.670 ms
(6 rows)

JDBC:

PreparedStatement count =
connection.prepareStatement("SELECT count(*) FROM
upc WHERE name like upper(?)||'%' ");

count.setString(1,"Aba");
ResultSet rs = count.executeQuery(); //<== this takes about 82 seconds
to execute

psql (PostgreSQL) 8.1.5
postgresql-jdbc-8.3-603

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