Merge "Add missing documentation of secondary index configuration" into stable-2.8
diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index 4cb3aa1..fdd593a 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -1853,6 +1853,47 @@
the link:pgm-reindex.html[reindex program] before restarting the
Gerrit server.
+Open and closed changes are indexed in separate indexes named
+'changes_open' and 'changes_closed' respectively.
+
+[[index.name.ramBufferSize]]index.name.ramBufferSize::
++
+Only used when the type is `LUCENE`.
++
+Determines the amount of RAM that may be used for buffering added documents
+and deletions before they are flushed to the index. See the
+link:http://lucene.apache.org/core/4_6_0/core/org/apache/lucene/index/LiveIndexWriterConfig.html#setRAMBufferSizeMB(double)[
+Lucene documentation] for further details.
++
+Defaults to 16M.
+
+[[index.name.maxBufferedDocs]]index.name.maxBufferedDocs::
++
+Only used when the type is `LUCENE`.
++
+Determines the minimal number of documents required before the buffered
+in-memory documents are flushed to the index. Large values generally
+give faster indexing. See the
+link:http://lucene.apache.org/core/4_6_0/core/org/apache/lucene/index/LiveIndexWriterConfig.html#setMaxBufferedDocs(int)[
+Lucene documentation] for further details.
++
+Defaults to -1, meaning no maximum is set and the writer will flush
+according to RAM usage.
+
+Sample index configuration:
+----
+[index]
+ type = LUCENE
+
+[index "changes_open"]
+ ramBufferSize = 60 m
+ maxBufferedDocs = 3000
+
+[index "changes_closed"]
+ ramBufferSize = 20 m
+ maxBufferedDocs = 500
+----
+
[[ldap]]Section ldap
~~~~~~~~~~~~~~~~~~~~
