On Mon, Mar 7, 2011 at 5:27 PM, Fujii Masao <masao.fu...@gmail.com> wrote: > On Mon, Mar 7, 2011 at 7:51 AM, Simon Riggs <si...@2ndquadrant.com> wrote: >> Efficient transaction-controlled synchronous replication. >> If a standby is broadcasting reply messages and we have named >> one or more standbys in synchronous_standby_names then allow >> users who set synchronous_replication to wait for commit, which >> then provides strict data integrity guarantees. Design avoids >> sending and receiving transaction state information so minimises >> bookkeeping overheads. We synchronize with the highest priority >> standby that is connected and ready to synchronize. Other standbys >> can be defined to takeover in case of standby failure. >> >> This version has very strict behaviour; more relaxed options >> may be added at a later date. > > Pretty cool! I'd appreciate very much your efforts and contributions.
Here are another comments:
if ((wrote_xlog && XactSyncCommit) || forceSyncCommit || nrels > 0 ||
SyncRepRequested())
Whenever synchronous_replication is TRUE, we disable synchronous_commit.
But, before disabling that, we should check also max_wal_senders and
synchronous_standby_names? Otherwise, synchronous_commit can
be disabled unexpectedly even in non replication case.
- /* Let the master know that we received some data. */
- XLogWalRcvSendReply();
- XLogWalRcvSendHSFeedback();
This change completely eliminates the difference between write_location
and flush_location in pg_stat_replication. If this change is reasoable, we
should get rid of write_location from pg_stat_replication since it's useless.
If not, this change should be reverted. I'm not sure whether monitoring
the difference between write and flush locations is useful. But I guess that
someone thought so and that code was added.
+ /*
+ * Current location of the head of the queue. All waiters should have
+ * a waitLSN that follows this value, or they are currently being woken
+ * to remove themselves from the queue. Protected by SyncRepLock.
+ */
+ XLogRecPtr lsn;
The comment ", or they are currently being woken to remove themselves
from the queue" is no longer required because the proc is currently removed
by walsender.
I found some typos. The attached patch fixes them.
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
sync_rep_typo_fix_v1.patch
Description: Binary data
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