From e9eb3af852778a67533e9579b14695763535d262 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Thu, 13 Jun 2019 00:29:37 +0000
Subject: xcpdb: support resharding v2 repos

v2 repos are sometimes created on machines where CPU
parallelization exceeds the capability of the storage devices.

In that case, users may reshard the Xapian DB to any smaller,
positive integer to avoid excessive overhead and contention when
bottlenecked by slow storage.

Resharding can also be used to increase shard count after
hardware upgrades.
---
 Documentation/public-inbox-xcpdb.pod | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'Documentation')

diff --git a/Documentation/public-inbox-xcpdb.pod b/Documentation/public-inbox-xcpdb.pod
index a04fd374..fd8770a4 100644
--- a/Documentation/public-inbox-xcpdb.pod
+++ b/Documentation/public-inbox-xcpdb.pod
@@ -30,6 +30,17 @@ preferable for gigantic inboxes where the coarse-grained lock
 currently required for L<public-inbox-compact(1)> can cause
 the compaction to take hours at-a-time.
 
+=item --reshard=N / -R N
+
+Repartition the Xapian database on a L<v2|public-inbox-v2-format(5)>
+inbox to C<N> partitions.  Since L<xapian-compact(1)> is not suitable
+for merging, users can rely on this switch to repartition the
+existing Xapian database(s) to any positive value of C<N>.
+
+This is useful in case the Xapian DB was created with too few or
+too many partitions given the capabilities of the current
+hardware.
+
 =item --blocksize / --no-full / --fuller
 
 These options are passed directly to L<xapian-compact(1)> when
-- 
cgit v1.2.3-24-ge0c7