Re: [Hsqldb-user] HSQL Memory Management with new Java types.

[fredt <fr...@us...>]

The org.hsqldb.store.ValuePool is responsible for managing object pooling. 
You may get better results by increasing the buffer sizes there for Long and 
Double values.

Fred
----- Original Message ----- 
From: "misha" <mi...@ho...>
To: <hsq...@li...>
Sent: 28 November 2008 01:56
Subject: [Hsqldb-user] HSQL Memory Management with new Java types.



I have a following problem: multiple users of my web app select a big 
dataset
from a hypersonic table help in memory which is placed into their http
session which causes the heap to grow significantly with each select and
eventually make the system run out of memory. I was under impression that
running the same query on a table multiple times results in the same exact
Java objects being returned in the result set, but after writing a simple
unit test I figured out that this was only partially true.  After the data
is placed into a table with a prepared statement, selecting the BigDecimal
and Strings result in returning the original objects (determined by hash
code value and == operator) which is not true about Longs and Doubles
however: they come back as different objects.  About 40% of my result
datasets are Doubles and Longs which makes the memory grow with each select
in the scenario I described above since each user gets their own copy
representing the same data.  Is this by design?  Is there anything I can set
on Hypersonic datasource which would cause same exact objects to be returned
over and over again as long as it represents the same data?

Thanks so much,
Mikhail

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