diff options
Diffstat (limited to 'src/backend/storage/ipc/README')
| -rw-r--r-- | src/backend/storage/ipc/README | 18 |
1 files changed, 2 insertions, 16 deletions
diff --git a/src/backend/storage/ipc/README b/src/backend/storage/ipc/README index 857e9cd833d..9a4d7b8156c 100644 --- a/src/backend/storage/ipc/README +++ b/src/backend/storage/ipc/README @@ -1,4 +1,4 @@ -$Header: /cvsroot/pgsql/src/backend/storage/ipc/README,v 1.2 2002/09/20 03:53:55 momjian Exp $ +$Header: /cvsroot/pgsql/src/backend/storage/ipc/README,v 1.3 2003/07/24 22:04:09 tgl Exp $ Mon Jul 18 11:09:22 PDT 1988 W.KLAS Cache invalidation synchronization routines: @@ -9,23 +9,9 @@ backend can register a message which then has to be read by all backends. A message read by all backends is removed from the queue automatically. If a message has been lost because the buffer was full, all backends that haven't read this message will be -noticed that they have to reset their cache state. This is done +told that they have to reset their cache state. This is done at the time when they try to read the message queue. The message queue is implemented as a shared buffer segment. Actually, the queue is a circle to allow fast inserting, reading (invalidate data) and maintaining the buffer. - -Access to this shared message buffer is synchronized by the lock manager. -The lock manager treats the buffer as a regular relation and sets -relation level locks (with mode = LockWait) to block backends while -another backend is writing or reading the buffer. The identifiers used -for this special 'relation' are database id = 0 and relation id = 0. - -The current implementation prints regular (e)log information -when a message has been removed from the buffer because the buffer -is full, and a backend has to reset its cache state. The elog level -is NOTICE. This can be used to improve the behavior of backends -when invalidating or resetting their cache state. - - |