db-derby-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Brian Peterson" <publicay...@verizon.net>
Subject iterating over millions of rows
Date Tue, 20 Jan 2009 04:19:50 GMT
I have a big table, about 1 million rows, that I'm doing a simple "select *"
over. The table is depressingly simple, basically a big VARCHAR for bit data
that stores some serialized bytes. When I profile using VisualVM it seems
that it is spending most of its time in 

org.apache.derby.impl.store.raw.data.RAFContainer4.readFully

If I remember correctly, this gets invoked something like 3000 times. Is
there anything I can do to speed up iterating over this table? It is taking
about 30s to iterate over the 1 million records, but I could have up to 25
million.

It is an embedded db using 10.4, JDK 1.6.0_07, running on a Windows XP SP2
machine. I have page size set to the max, 32K, and the page case size set to
6000 pages. 

Is there anything I can do, or have I just run up against how fast Windows
can read off of the disk?

Brian




Mime
View raw message