This documentation is for Dovecot v2.x, see wiki1 for v1.x documentation.

LDA Indexing

LDA's indexing basically does two things while message is being saved:

  1. It updates the main index file.
    • This improves performance with mbox format, especially if mbox_very_dirty_syncs=no.

    • With Maildir the benefits of this are almost irrelevant.

  2. It updates the dovecot.index.cache file.

Cache file

The LDA also updates the cache file, which can be very useful with all mailbox formats. It means that when an IMAP client wants to fetch the message's metadata (e.g. some header fields), they're can be retrieved from the cache file and Dovecot doesn't have to open and parse the message file. There are some tradeoffs though:

So it depends on IMAP client if it's faster to use LDA or IMAP time indexing. In any case the user experience is typically faster with LDA indexing, because the message list metadata can be returned faster when it's pre-indexed.

See IndexFiles for more information about what the index files contain.

Non-indexed mail delivery

Ignoring the benefits of cache file updates, the only thing left is the main index updates. As mentioned above, with Maildir format these benefits are very small. This also means that it's perfectly fine to use a non-Dovecot MDA to deliver mails that doesn't update indexes. Dovecot can efficiently see and index such new mails without doing anything expensive like "rebuilding indexes".

LDA/Indexing (last edited 2010-10-08 17:25:26 by RalfHildebrandt)