doc: various updates to reflect current state

-index documentation avoid redundant v1 information and refers
readers to apropriate v1/v2 manpages.  Search::Xapian can also
be optional, now, as only the PSGI search interface uses it.

Favor "INBOX_DIR" where appropriate, since "REPO_DIR" can be
confused for code repos which we also support.

XAPIAN_FLUSH_THRESHOLD is documented for all relevant
bulk commands.

1 files changed, 29 insertions, 51 deletions

diff --git a/Documentation/public-inbox-index.pod b/Documentation/public-inbox-index.pod
index acc90392..2e0ff693 100644
--- a/Documentation/public-inbox-index.pod
+++ b/Documentation/public-inbox-index.pod
@@ -4,14 +4,15 @@ public-inbox-index - create and update search indices
 
 =head1 SYNOPSIS
 
-public-inbox-index [OPTIONS] REPO_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
@@ -22,10 +23,10 @@ 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
 
@@ -45,50 +46,11 @@ This does not touch the NNTP article number database.
 
 =head1 FILES
 
+For v1 (ssoma) repositories described in L<public-inbox-v1-format>.
 All public-inbox-specific files are contained within the
-C<$REPO_DIR/public-inbox/> directory.  All files are expected to
-grow in size as more messages are archived, so using compaction
-commands (e.g. L<xapian-compact(1)>) is not recommended unless
-the list is no longer active.
+C<$GIT_DIR/public-inbox/> directory.
 
-=over
-
-=item $REPO_DIR/public-inbox/msgmap.sqlite3
-
-The stable NNTP article number to Message-ID mapping is
-stored in an SQLite3 database.
-
-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.
-
-This file is relatively small, and typically less than 5%
-of the space of the mail stored in a packed git repository.
-
-=item $REPO_DIR/public-inbox/xapian*
-
-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.
-
-These directories may be safely deleted or removed in full
-while the NNTP and HTTP interfaces are no longer accessing
-them.
-
-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 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.
+v2 repositories are described in L<public-inbox-v2-format>.
 
 =back
 
@@ -100,8 +62,24 @@ C<--reindex> option makes it larger, still.
 
 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.
+
+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 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>
@@ -111,7 +89,7 @@ and L<http://hjrcffqmbrq6wope.onion/meta/>
 
 =head1 COPYRIGHT
 
-Copyright 2016-2018 all contributors L<mailto:meta@public-inbox.org>
+Copyright 2016-2019 all contributors L<mailto:meta@public-inbox.org>
 
 License: AGPL-3.0+ L<https://www.gnu.org/licenses/agpl-3.0.txt>