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
