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https://issues.apache.org/jira/browse/DERBY-4661?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kristian Waagan updated DERBY-4661:
-----------------------------------
Attachment: derby-4661-1a-reduce_encoding_bz.diff
derby-4661-1a-reduce_encoding_bz.stat
Attaching patch 1a.
* iapi/types/ReaderToUTF8Stream
The actual fix. Note the special case when the value length is zero. To avoid
the issue for shorter header lengths in the future, I used Math.max instead of
handling valueLength == 0 specifically.
* other classes
Added StreamHeaderGenerater.getMaxHdrLength() and made SQLClob use it.
Some simple tests showed a performance improvement of around 30%. Real world
workloads will not see such a gain, but the fix may help heavily loaded servers
somewhat where users are inserting small data values using the streaming
classes.
Regression tests passed.
Patch ready for review.
> Reduce size of encoding buffer for short character values
> ---------------------------------------------------------
>
> Key: DERBY-4661
> URL: https://issues.apache.org/jira/browse/DERBY-4661
> Project: Derby
> Issue Type: Improvement
> Components: JDBC
> Affects Versions: 10.7.0.0
> Environment: Inserts using setXStream(int, Reader/InputStream,
> int/long) for short values on character columns
> Reporter: Kristian Waagan
> Assignee: Kristian Waagan
> Priority: Minor
> Attachments: derby-4661-1a-reduce_encoding_bz.diff,
> derby-4661-1a-reduce_encoding_bz.stat
>
>
> When inserting character values Derby converts from Java char to an on-disk
> encoding of UTF-8. To to this, the user stream is read and the resulting
> bytes after conversion are placed in a "translation buffer". The default size
> of the buffer is 32 KB. When inserting a lot of short values, the pressure on
> the Java garbage collector is unnecessary high and the allocation/GC also
> causes a somewhat higher CPU usage.
> This effect of this issue can easily be reduced by sizing the buffer in the
> appropriate cases.
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