Xapian for searching

Cyrus can be configured to use Xapian to power its searches.

Compiling Xapian for Cyrus

Note

If CJK support is not required in your environment, you can use Cyrus with a standard upstream Xapian 1.4 release. Skip this section and move straight on to Configuring Xapian. If you need CJK support, you will still need to use the cyruslibs Xapian fork and compile from source.

The cyrusimap/cyruslibs repository provides a pre-patched copy of 1.5-dev Xapian, ready for use with Cyrus. We are working on having the patches integrated upstream.

Compiling Xapian requires gcc 4.9 or later.

To build Xapian, fetch the cyruslibs package which comes with pre-patched Xapian and some other dependencies. They are installed in /usr/local/cyruslibs by default unless overridden on the command line.

export CYRUSLIBS="/usr/local/cyruslibs"
export PKG_CONFIG_PATH="$CYRUSLIBS/lib/pkgconfig:$PKG_CONFIG_PATH"
export LDFLAGS="-Wl,-rpath,$CYRUSLIBS/lib -Wl,-rpath,$CYRUSLIBS/lib/x86_64-linux-gnu"
export PATH="$PATH:$CYRUSLIBS/bin"

git clone git@github.com:cyrusimap/cyruslibs.git
cd cyruslibs
sh build.sh $CYRUSLIBS_DIR

Then follow on with the Cyrus compilation instructions, adding --enable-xapian to the flags to ./configure.

Additional dependencies required for Cyrus with Xapian support

When building Cyrus with Xapian support enabled, the following additional packages are required:

  • rsync (used when compacting databases)

Configuring Xapian

Xapian requires a running squatter(8) instance:

  • In cyrus.conf(5) set up a daemon squatter to run:

    DAEMON {
  # run a rolling squatter
  squatter cmd="squatter -R"
}

  • Enable sync logging: Set sync_log: on in imapd.conf(5).

  • Add a squatter sync log channel: sync_log_channels: squatter in imapd.conf(5).

You also need (at least one) search tier. Add this to imapd.conf(5).

search_engine: xapian
search_index_headers: no
search_batchsize: 8192
defaultpartition: base
defaultsearchtier: t1
partition-base: /var/cyrus/spool
t1searchpartition-base: /var/cyrus/search

If you want to do more complex search tiers and repacking, you'll want to read:

http://lists.tartarus.org/pipermail/xapian-discuss/2014-October/009112.html