Re: flatcurve index size (10x larger than lucene)

On 14/05/2026 23:21 EEST Jean-Daniel Beaubien via dovecot <dovecot@dovecot.org> wrote:

Hi everyone,

I am currently trying to update from an old dovecot 2.3 setup with fts-lucene to 2.4.2 with fts-flatcurve.

However, I am seeing a giant jump in the size of the indexes.

For an email account that takes 12GB of storage, I get the following index sizes:

• lucene: 270 MB
• flatcurve: 2400 MB

That is almost a 10x increase in the index size (with flatcurve the indexes represent 20% of the size of the mailbox).

Hi!

You have substring search enabled, that will incur a larger size as those substrings need to be indexed somewhere.

Aki