# CustomSqlChange checksum

**URL:** <https://forum.liquibase.org/t/customsqlchange-checksum/1263>\
**Category:** General Discussion\
**Created:** [May 9, 2011, 4:56pm UTC](https://forum.liquibase.org/t/customsqlchange-checksum/1263 "2011-05-09T16:56:00Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![adam.dajka](https://avatars.discourse-cdn.com/v4/letter/a/f14d63/32.png) [@adam.dajka](https://forum.liquibase.org/u/adam.dajka)\
**Post date:** [May 9, 2011, 4:56pm UTC](https://forum.liquibase.org/t/customsqlchange-checksum/1263/1 "2011-05-09T16:56:00Z")

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Hi!

Can you tell me exactly how liquibase calculates checksums for custom refactoring classes?

I couldn’t find any information about this in the manual.

Thanks.

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**Author:** ![Guest](https://avatars.discourse-cdn.com/v4/letter/g/8dc957/32.png) [@Guest](https://forum.liquibase.org/u/Guest)\
**Post date:** [May 9, 2011, 4:56pm UTC](https://forum.liquibase.org/t/customsqlchange-checksum/1263/2 "2011-05-09T16:56:00Z")

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It is purely based on the attributes and values in the XML of the custom change.&nbsp;

If you use the extension framework with 2.0 ([liquibase.org/extensions](http://liquibase.org/extensions)) you can have better control over how the checksums are generated.

Nathan