[COUCHDB-1021] Compacting a database does not preserve the purge_seq

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.0.1
• Fix Version/s: 1.0.2, 1.1
• Component/s: Database Core

Environment

All platforms

• Skill Level: Regular Contributors Level (Easy to Medium)
• Assignee: Unassigned
• Reporter: Mike Leddy
• Created: 11/Jan/11 15:34
• Updated: 12/Jan/11 04:56
• Resolved: 12/Jan/11 04:56

Description

On compacting a database the purge_seq becomes zero. As a result subsequently accessing any view will cause the view to be rebuilt from scratch. I resolved the issue for me by patching start_copy_compact, but this only works if you can guarantee there will be no purging done during compaction:

— couchdb-1.0.1/src/couchdb/couch_db_updater.erl
+++ couchdb-1.0.1.new/src/couchdb/couch_db_updater.erl
@@ -857,7 +857,7 @@

commit_data(NewDb4#db

{update_seq=Db#db.update_seq}

).

-start_copy_compact(#db

{name=Name,filepath=Filepath}

=Db) ->
+start_copy_compact(#db{name=Name,filepath=Filepath,header=#db_header{purge_seq=PurgeSeq}}=Db) ->
CompactFile = Filepath ++ ".compact",
?LOG_DEBUG("Compaction process spawned for db \"~s\"", [Name]),
case couch_file:open(CompactFile) of
@@ -869,7 +869,7 @@
couch_task_status:add_task(<<"Database Compaction">>, Name, <<"Starting">>),

{ok, Fd}

= couch_file:open(CompactFile, [create]),
Retry = false,

• ok = couch_file:write_header(Fd, Header=#db_header{})
  + ok = couch_file:write_header(Fd, Header=#db_header {purge_seq=PurgeSeq}

  )
  end,
  NewDb = init_db(Name, CompactFile, Fd, Header),
  unlink(Fd),

I am sure that there must be a better way of doing this.....