+v2 inboxes are described in L<public-inbox-v2-format(5)>.
+
+=head1 CONFIGURATION
+
+=over 8
+
+=item publicinbox.indexMaxSize
+
+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.
+
+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 option is only available in public-inbox 1.5 or later.
+
+Default: none
+
+=item publicinbox.indexBatchSize
+
+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)>.
+
+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.
+
+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>.
+
+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 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+is in use may leave the search indices out-of-date with respect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 (PENDING).
+
+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>.