On Wed, Jun 10, 2015 at 8:07 AM, Andres Freund <andres@anarazel.de> wrote:
On 2015-06-10 08:00:28 -0700, Gurjeet Singh wrote: > pg_create_logical_replication_slot() prevents LSN from being > recycled that by looping (worst case 2 times) until there's no > conflict with the checkpointer recycling the segment. So I have used > the same approach.
There's no need to change anything for logical slots? Or do you just mean that you moved the existing code?
Yes, I turned the code from logical replication into a function and used it from logical and physical replication.
> > /* > + * Grab and save an LSN value to prevent WAL recycling past that point. > + */ > +void > +ReplicationSlotRegisterRestartLSN() > +{
...
> + /* > + * Let's start with enough information if we can, so log a standby > + * snapshot and start decoding at exactly that position. > + */ > + if (!RecoveryInProgress()) > + { > + XLogRecPtr flushptr; > + > + /* start at current insert position */ > + slot->data.restart_lsn = GetXLogInsertRecPtr(); > + > + /* make sure we have enough information to start */ > + flushptr = LogStandbySnapshot(); > + > + /* and make sure it's fsynced to disk */ > + XLogFlush(flushptr); > + } > + else > + slot->data.restart_lsn = GetRedoRecPtr(); > +
That doesn't look right to me. Why is this code logging a standby snapshot for physical slots?
This is the new function I referred to above. The logging of the snapshot is in 'not RecoveryInProgress()' case, meaning it's running in primary and not in a standby.
