diff --git a/doc/user/replication.xml b/doc/user/replication.xml index cd54a9556c987c8bc74b729d5e57955d7d685ab5..025c103ba7783a2870ce5a95906f87dc3dce5338 100644 --- a/doc/user/replication.xml +++ b/doc/user/replication.xml @@ -32,17 +32,17 @@ identifier which is unique within the cluster, known as the A replica gets all updates from the master by continuously fetching and applying its write-ahead log (WAL). Each record in the WAL represents a single Tarantool - command such as INSERT or UPDATE or DELETE, and is assigned + data-change request such as INSERT or UPDATE or DELETE, and is assigned a monotonically growing log sequence number (LSN). In essence, Tarantool replication is row-based: - all data change commands are fully deterministic and operate - on a single record. + each data change command is fully deterministic and operate + on a single tuple. </para> <para> A stored program invocation <!-- , unless requested explicitly, --> is not written to the write-ahead log. Instead, log events - for actual UPDATEs and DELETEs, performed by the Lua code, + for actual data-change requests, performed by the Lua code, are written to the log. This ensures that possible non-determinism of Lua does not cause replication to go out of sync. @@ -85,7 +85,7 @@ identifier which is unique within the cluster, known as the If this first <code>box.cfg</code> request occurs with a "replication_source" clause, then the server is a replica and its snapshot file, along with the cluster information, - is copied from the master. Therefore, + is constructed from the write-ahead logs of the master. Therefore, to start replication, specify <olink targetptr="replication_source"/> in a <code>box.cfg</code> request. When a replica contacts a master for the first time, it becomes part of a cluster. @@ -99,6 +99,7 @@ identifier which is unique within the cluster, known as the A replica can be "re-seeded" by deleting all its files (the snapshot .snap file and the WAL .xlog files), then starting replication again -- the replica will then catch up with the master by retrieving all the master's tuples. + Again, this procedure works only if the master's WAL files are present. </para> <note><simpara> Replication parameters are "dynamic", which allows the