=head1 SYNOPSIS
-public-inbox-index [OPTIONS] GIT_DIR
+public-inbox-index [OPTIONS] INBOX_DIR...
=head1 DESCRIPTION
-public-inbox-index creates and updates the search and NNTP
-article number database used by the read-only public-inbox HTTP
-and NNTP interfaces. Currently, this requires L<Search::Xapian>
-and L<DBD::SQlite> and L<DBI> Perl modules.
+public-inbox-index creates and updates the search, overview and
+NNTP article number database used by the read-only public-inbox
+HTTP and NNTP interfaces. Currently, this requires
+L<DBD::SQLite> and L<DBI> Perl modules. L<Search::Xapian>
+is optional, only to support the PSGI search interface.
Once the initial indices are created by public-inbox-index,
L<public-inbox-mda(1)> and L<public-inbox-watch(1)> will
or if upgrading to a new version of public-inbox using
the C<--reindex> option.
-Having a search and article number database is essential to
+Having the overview and article number database is essential to
running the NNTP interface, and strongly recommended for the
-HTTP interface as it provides thread grouping in addition
-to normal search functionality.
+HTTP interface as it provides thread grouping in addition to
+normal search functionality.
=head1 OPTIONS
=over
+=item --compact / -c
+
+Compacts the Xapian DBs after indexing. This is recommended
+when using C<--reindex> to avoid running out of disk space
+while indexing multiple inboxes.
+
+While option takes a negligible amount of time compared to
+C<--reindex>, it requires temporarily duplicating the entire
+contents of the Xapian DB.
+
+This switch may be specified twice, in which case compaction
+happens both before and after indexing to minimize the temporal
+footprint of the (re)indexing operation.
+
=item --reindex
-Forces a search engine re-index of all messages in the
-repository. This can be used for in-place upgrades while
+Forces a re-index of all messages in the inbox.
+This can be used for in-place upgrades and bugfixes while
NNTP/HTTP server processes are utilizing the index. Keep in
mind this roughly doubles the size of the already-large
-Xapian database.
+Xapian database. Using this with C<--compact> or running
+L<public-inbox-compact(1)> afterwards is recommended to
+release free space.
+
+This does not touch the NNTP article number database or
+affect threading.
+
+=item --prune
-This does not touch the NNTP article number database.
+Run L<git-gc(1)> to prune and expire reflogs if discontiguous history
+is detected. This is intended to be used in mirrors after running
+L<public-inbox-edit(1)> or L<public-inbox-purge(1)> to ensure data
+is expunged from mirrors.
=back
=head1 FILES
+For v1 (ssoma) repositories described in L<public-inbox-v1-format>.
All public-inbox-specific files are contained within the
-C<$GIT_DIR/public-inbox/> directory. All files are expected to
-grow in size as more messages are archived, so using compaction
-commands (e.g. L<xapian-compact(1)>) is not recommended unless
-the list is no longer active.
+C<$GIT_DIR/public-inbox/> directory.
-=over
-
-=item $GIT_DIR/public-inbox/msgmap.sqlite3
-
-The stable NNTP article number to Message-ID mapping is
-stored in an SQLite3 database.
+v2 inboxes are described in L<public-inbox-v2-format>.
-This is required for users of L<public-inbox-nntpd(1)>, but
-users of the L<PublicInbox::WWW> interface will find it
-useful for attempting recovery from copy-paste truncations of
-URLs containing long Message-IDs.
-
-Avoid removing this file and regenerating it; it may cause
-existing NNTP readers to lose sync and miss (or see duplicate)
-messages.
+=head1 ENVIRONMENT
-This file is relatively small, and typically less than 5%
-of the space of the mail stored in a packed git repository.
+=over 8
-=item $GIT_DIR/public-inbox/xapian*
+=item PI_CONFIG
-The database used by L<Search::Xapian>. This directory name is
-followed by a number indicating the index schema version this
-installation of public-inbox uses.
+Used to override the default "~/.public-inbox/config" value.
-These directories may be safely deleted or removed in full
-while the NNTP and HTTP interfaces are no longer accessing
-them.
+=item XAPIAN_FLUSH_THRESHOLD
-In addition to providing a search interface for the HTTP
-interface, the Xapian database is used to group and combine
-related messages into threads. For NNTP servers, it also
-provides a cache of metadata and header information often
-requested by NNTP clients.
+The number of documents to update before committing changes to
+disk. This environment is handled directly by Xapian, refer to
+Xapian API documentation for more details.
-This directory is large, often two to three times the size of
-the objects stored in a packed git repository. Using the
-C<--reindex> option makes it larger, still.
+Default: our indexing code flushes every megabyte of mail seen
+to keep memory usage low. Setting this environment variable to
+any positive value will switch to a document count-based
+threshold in Xapian.
=back
-=head1 ENVIRONMENT
-
-=over 8
+=head1 UPGRADING
-=item PI_CONFIG
-
-Used to override the default "~/.public-inbox/config" value.
-
-=back
+Occasionally, public-inbox will update it's schema version and
+require a full index by running this command.
=head1 CONTACT
=head1 COPYRIGHT
-Copyright 2016-2018 all contributors L<mailto:meta@public-inbox.org>
+Copyright 2016-2020 all contributors L<mailto:meta@public-inbox.org>
License: AGPL-3.0+ L<https://www.gnu.org/licenses/agpl-3.0.txt>