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.\" ========================================================================
.\"
.IX Title "Lucy::Index::BackgroundMerger 3pm"
.TH Lucy::Index::BackgroundMerger 3pm "2015-03-06" "perl v5.20.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
Lucy::Index::BackgroundMerger \- Consolidate index segments in the background.
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 4
\&    my $bg_merger = Lucy::Index::BackgroundMerger\->new(
\&        index  => \*(Aq/path/to/index\*(Aq,
\&    );
\&    $bg_merger\->commit;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Adding documents to an index is usually fast, but every once in a while the
index must be compacted and an update takes substantially longer to
complete.  See Lucy::Docs::Cookbook::FastUpdates for how to use
this class to control worst-case index update performance.
.PP
As with Indexer, see
Lucy::Docs::FileLocking if your index is on a shared volume.
.SH "CONSTRUCTORS"
.IX Header "CONSTRUCTORS"
.SS "new( \fI[labeled params]\fP )"
.IX Subsection "new( [labeled params] )"
.Vb 4
\&    my $bg_merger = Lucy::Index::BackgroundMerger\->new(
\&        index   => \*(Aq/path/to/index\*(Aq,    # required
\&        manager => $manager             # default: created internally
\&    );
.Ve
.PP
Open a new BackgroundMerger.
.IP "\(bu" 4
\&\fBindex\fR \- Either a string filepath or a Folder.
.IP "\(bu" 4
\&\fBmanager\fR \- An IndexManager.  If not supplied, an IndexManager with
a 10\-second write lock timeout will be created.
.SH "METHODS"
.IX Header "METHODS"
.SS "\fIcommit()\fP"
.IX Subsection "commit()"
Commit any changes made to the index.  Until this is called, none of
the changes made during an indexing session are permanent.
.PP
Calls \fIprepare_commit()\fR implicitly if it has not already been called.
.SS "\fIprepare_commit()\fP"
.IX Subsection "prepare_commit()"
Perform the expensive setup for \fIcommit()\fR in advance, so that \fIcommit()\fR
completes quickly.
.PP
Towards the end of \fIprepare_commit()\fR, the BackgroundMerger attempts to
re-acquire the write lock, which is then held until \fIcommit()\fR finishes
and releases it.
.SS "\fIoptimize()\fP"
.IX Subsection "optimize()"
Optimize the index for search-time performance.  This may take a
while, as it can involve rewriting large amounts of data.
.SH "INHERITANCE"
.IX Header "INHERITANCE"
Lucy::Index::BackgroundMerger isa Lucy::Object::Obj.