Re: Performance of jdbc insert statements and select nextval

thanks for your hint.

i have tested this, and you'r right. Packaging my requests into chunks of
1000 each, i can execute 10000 inserts within 2 seconds. This is exactly
the performance of PGAdmin Tool and 5 times faster then performing an
execute per each object. By the way, when i was talking about explain i
was thinking of explain analyse and this statement produces a total
runtime in milliseconds. So the execution time of 0,2 ms per insert is
close to the cost estimate of explain (analyse).

Thanks for your help,
Ralf

Kris Jurka <books(at)ejurka(dot)com>
Gesendet von: pgsql-jdbc-owner(at)postgresql(dot)org
20.02.2009 18:59

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ralf(dot)baumhof(at)bgs-ag(dot)de
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Re: [JDBC] Performance of jdbc insert statements and select nextval

On Fri, 20 Feb 2009, ralf(dot)baumhof(at)bgs-ag(dot)de wrote:

> [insert with pgadmin is faster than JDBC]

As I explained previously I believe pgadmin is sending all of your inserts

in one network roundtrip rather than a single insert at a time. So for
example:

StringBuffer sql = new StringBuffer();
for (int i=0; i<100; i++) {
sql.append("INSERT INTO mytable (a) VALUES (");
sql.append(i).append(")");
}
Statement.execute(sql.toString())

will be faster than

for (int i=0; i<100; i++) {
String sql = "INSERT INTO mytable (a) VALUES (" + i +
")";
Statement.execute(sql);
}

because the second sample has to make 100 network trips instead of just
one.

> I made a test with "logical" insert of objects which results in 50000
> inserts can be done within 2 minutes, what means 416 inserts per second,

> or 1 insert in 2/1000 sec (2ms). The cost estimate with explain for an
> insert is on the other hand is 0,4 ms.

Explain cost estimates do not have units of milliseconds, so the
comparison is invalid.

Kris Jurka

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