=head1 SYNOPSIS
-public-inbox-index GIT_DIR
+public-inbox-index [OPTIONS] INBOX_DIR...
+
+public-inbox-index [OPTIONS] --all
=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
automatically maintain them.
Running this manually to update indices is only required if
-relying on L<git-fetch(1)> to mirror an existing public-inbox.
+relying on L<git-fetch(1)> to mirror an existing public-inbox;
+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 --jobs=JOBS, -j
+
+Influences the number of Xapian indexing shards in a
+(L<public-inbox-v2-format(5)>) inbox.
+
+See L<public-inbox-init(1)/--jobs> for a full description
+of sharding.
+
+C<--jobs=0> is accepted as of public-inbox 1.6.0
+to disable parallel indexing regardless of the number of
+pre-existing shards.
+
+If the inbox has not been indexed or initialized, C<JOBS - 1>
+shards will be created (one job is always needed for indexing
+the overview and article number mapping).
+
+Default: the number of existing Xapian shards
+
+=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.
+
+Available since public-inbox 1.4.0.
+
+=item --reindex
+
+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. Using this with C<--compact> or running
+L<public-inbox-compact(1)> afterwards is recommended to
+release free space.
+
+public-inbox protects writes to various indices with
+L<flock(2)>, so it is safe to reindex (and rethread) while
+L<public-inbox-watch(1)>, L<public-inbox-mda(1)> or
+L<public-inbox-learn(1)> run.
+
+This does not touch the NNTP article number database.
+It does not affect threading unless C<--rethread> is
+used.
+
+=item --all
+
+Index all inboxes configured in ~/.public-inbox/config.
+This is an alternative to specifying individual inboxes directories
+on the command-line.
+
+=item --rethread
+
+Regenerate internal THREADID and message thread associations
+when reindexing.
+
+This fixes some bugs in older versions of public-inbox. While
+it is possible to use this without C<--reindex>, it makes little
+sense to do so.
+
+Available in public-inbox 1.6.0+.
+
+=item --prune
+
+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.
+
+Available since public-inbox 1.2.0.
+
+=item --max-size SIZE
+
+Sets or overrides L</publicinbox.indexMaxSize> on a
+per-invocation basis. See L</publicinbox.indexMaxSize>
+below.
+
+Available since public-inbox 1.5.0.
+
+=item --batch-size SIZE
+
+Sets or overrides L</publicinbox.indexBatchSize> on a
+per-invocation basis. See L</publicinbox.indexBatchSize>
+below.
+
+When using rotational storage but abundant RAM, using a large
+value (e.g. C<500m>) with C<--sequential-shard> can
+significantly speed up and reduce fragmentation during the
+initial index and full C<--reindex> invocations (but not
+incremental updates).
+
+Available in public-inbox 1.6.0+.
+
+=item --no-fsync
+
+Disables L<fsync(2)> and L<fdatasync(2)> operations on SQLite
+and Xapian. This is only effective with Xapian 1.4+. This is
+primarily intended for systems with low RAM and the small
+(default) C<--batch-size=1m>. Users of large C<--batch-size>
+may even find disabling L<fdatasync(2)> causes too much dirty
+data to accumulate, resulting on latency spikes from writeback.
+
+Available in public-inbox 1.6.0+.
+
+=item --sequential-shard
+
+Sets or overrides L</publicinbox.indexSequentialShard> on a
+per-invocation basis. See L</publicinbox.indexSequentialShard>
+below.
+
+Available in public-inbox 1.6.0+.
+
+=item --skip-docdata
+
+Stop storing document data in Xapian on an existing inbox.
+
+See L<public-inbox-init(1)/--skip-docdata> for description and caveats.
+
+Available in public-inbox 1.6.0+.
+
+=item --update-extindex=EXTINDEX, -E
+
+Update the given external index (L<public-inbox-extindex-format(5)>.
+Either the configured section name (e.g. C<all>) or a directory name
+may be specified.
+
+Defaults to C<all> if C<[extindex "all"]> is configured,
+otherwise no external indices are updated.
+
+May be specified multiple times in rare cases where multiple
+external indices are configured.
+
+=item --no-update-extindex
+
+Do not update the C<all> external index by default. This negates
+all uses of C<-E> / C<--update-extindex=> on the command-line.
+
+=back
=head1 FILES
+For v1 (ssoma) repositories described in L<public-inbox-v1-format(5)>.
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.
+
+v2 inboxes are described in L<public-inbox-v2-format(5)>.
+
+=head1 CONFIGURATION
+
+=over 8
+
+=item publicinbox.indexMaxSize
-=item $GIT_DIR/public-inbox/msgmap.sqlite3
+Prevents indexing of messages larger than the specified size
+value. A single suffix modifier of C<k>, C<m> or C<g> is
+supported, thus the value of C<1m> to prevents indexing of
+messages larger than one megabyte.
-The stable NNTP article number to Message-ID mapping is
-stored in an SQLite3 database.
+This is useful for avoiding memory exhaustion in mirrors
+via git. It does not prevent L<public-inbox-mda(1)> or
+L<public-inbox-watch(1)> from importing (and indexing)
+a message.
-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.
+This option is only available in public-inbox 1.5 or later.
-Avoid removing this file and regenerating it; it may cause
-existing NNTP readers to lose sync and miss (or duplicate)
-messages.
+Default: none
-This file is relatively small, and typically less than 5%
-of the space of the mail stored in a packed git repository.
+=item publicinbox.indexBatchSize
-=item $GIT_DIR/public-inbox/xapian*
+Flushes changes to the filesystem and releases locks after
+indexing the given number of bytes. The default value of C<1m>
+(one megabyte) is low to minimize memory use and reduce
+contention with parallel invocations of L<public-inbox-mda(1)>,
+L<public-inbox-learn(1)>, and L<public-inbox-watch(1)>.
-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.
+Increase this value on powerful systems to improve throughput at
+the expense of memory use. The reduction of lock granularity
+may not be noticeable on fast systems. With SSDs, values above
+C<4m> have little benefit.
-These directories may be safely deleted or removed in full
-while the NNTP and HTTP interfaces are no longer accessing
-them.
+For L<public-inbox-v2-format(5)> inboxes, this value is
+multiplied by the number of Xapian shards. Thus a typical v2
+inbox with 3 shards will flush every 3 megabytes by default
+unless parallelism is disabled via C<--sequential-shard>
+or C<--jobs=0>.
-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.
+This influences memory usage of Xapian, but it is not exact.
+The actual memory used by Xapian and Perl has been observed
+in excess of 10x this value.
-This directory is large, often two to three times the size of
-the objects stored in a packed git repository.
+This option is available in public-inbox 1.6 or later.
+public-inbox 1.5 and earlier used the current default, C<1m>.
+
+Default: 1m (one megabyte)
+
+=item publicinbox.indexSequentialShard
+
+For L<public-inbox-v2-format(5)> inboxes, setting this to C<true>
+allows indexing Xapian shards in multiple passes. This speeds up
+indexing on rotational storage with high seek latency by allowing
+individual shards to fit into the kernel page cache.
+
+Using a higher-than-normal number of C<--jobs> with
+L<public-inbox-init(1)> may be required to ensure individual
+shards are small enough to fit into cache.
+
+Warning: interrupting C<public-inbox-index(1)> while this option
+is in use may leave the search indices out-of-date with respect
+to SQLite databases. WWW and IMAP users may notice incomplete
+search results, but it is otherwise non-fatal. Using C<--reindex>
+will bring everything back up-to-date.
+
+Available in public-inbox 1.6.0+.
+
+This is ignored on L<public-inbox-v1-format(5)> inboxes.
+
+Default: false, shards are indexed in parallel
+
+=item publicinbox.<name>.indexSequentialShard
+
+Identical to L</publicinbox.indexSequentialShard>,
+but only affect the inbox matching E<lt>nameE<gt>.
+
+=back
=head1 ENVIRONMENT
Used to override the default "~/.public-inbox/config" value.
+=item XAPIAN_FLUSH_THRESHOLD
+
+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.
+
+For public-inbox 1.6 and later, use C<publicinbox.indexBatchSize>
+instead.
+
+Setting C<XAPIAN_FLUSH_THRESHOLD> or
+C<publicinbox.indexBatchSize> for a large C<--reindex> may cause
+L<public-inbox-mda(1)>, L<public-inbox-learn(1)> and
+L<public-inbox-watch(1)> tasks to wait long and unpredictable
+periods of time during C<--reindex>.
+
+Default: none, uses C<publicinbox.indexBatchSize>
+
=back
+=head1 UPGRADING
+
+Occasionally, public-inbox will update it's schema version and
+require a full index by running this command.
+
=head1 CONTACT
Feedback welcome via plain-text mail to L<mailto:meta@public-inbox.org>
-The mail archives are hosted at L<https://public-inbox.org/meta/>
-and L<http://hjrcffqmbrq6wope.onion/meta/>
+The mail archives are hosted at L<https://public-inbox.org/meta/> and
+L<http://4uok3hntl7oi7b4uf4rtfwefqeexfzil2w6kgk2jn5z2f764irre7byd.onion/meta/>
=head1 COPYRIGHT
-Copyright 2016 all contributors L<mailto:meta@public-inbox.org>
+Copyright 2016-2021 all contributors L<mailto:meta@public-inbox.org>
License: AGPL-3.0+ L<https://www.gnu.org/licenses/agpl-3.0.txt>
=head1 SEE ALSO
-L<Search::Xapian>, L<DBD::SQLite>
+L<Search::Xapian>, L<DBD::SQLite>, L<public-inbox-extindex-format(5)>