Change Jdbc4ResultSet to cache Jdbc4ResultSetMetaData instances

[stevenschlansker]

This dramatically improves performance with regards to
metadata-intensive operations. The original motivation is that without
caching, each call to a ResultSet.updateXXX method would retrieve a new
instance of the metadata, causing an entire query to be run. If you
update many columns in the same row, the cost came to be very expensive.

Performance may improve in other workloads as well, but this has not been
measured.

[kjurka]

The same change needs to be made in Jdbc3ResultSet and Jdbc2ResultSet unless you can rework the implementation so the caching happens in AbstractJdbc2ResultSet and works for all support JDBC versions.

[stevenschlansker]

Added an additional commit implementing the requested functionality. I assume you mean Jdbc3gResultSet not Jdbc2ResultSet, as I did not find a concrete implementation of the Jdbc2ResultSet.

[kjurka]

I went with a slightly different approach of doing the caching in AbstractJdbc2ResultSet.

[chrisfrenchy]

I've faced slower performances since 9.1 driver version.
After some investigations, I've found metadata caching has been changed, and I have introducted a new caching method allowing performances to be similar than of 9.0 driver version.

The method implements a caching object in the AbstractJdbc2ResultSetMetaData.

Has anybody else accountered this huge slow in performances ?
Is anybody interested in testing this caching ?

[davecramer]

Yes, can you send another pull so we can test it ?

[chrisfrenchy]

dave,

What do you mean about a pull ? (I am new to Github sorry !)

[davecramer]

Hmmm....

clone the official repo to yours
make a branch called caching or whatever
patch the code with your changes
push your changes to your repo
then you can create a pull request against the official repo

barring that send me your patch that applies to the current repo

Dave Cramer

On 27 May 2014 09:48, chrisfrenchy notifications@github.com wrote:

dave,

What do you mean about a pull ? (I am new to Github sorry !)

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Reply to this email directly or view it on GitHubhttps://github.com//pull/1#issuecomment-44278183
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[chrisfrenchy]

Ok ; I will do that