# Optimize notmuch's performance
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## Xapian 1.2.x database format: chert vs. flint
Xapian 1.2 (in contrast to 1.0.x) uses a new database format called
* [Sebastian Spaeth](http://notmuchmail.org/pipermail/notmuch/2011/004048.html)
* [Pieter Praet](http://notmuchmail.org/pipermail/notmuch/2011/004175.html)
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