Re: Fairly serious bug induced by latest guc enum changes

Magnus Hagander <magnus(at)hagander(dot)net> writes:
> Tom Lane wrote:
>> Hmm ... or at least more or less fixed. Seems like there's no provision
>> to close and reopen the file if enableFsync changes. Not sure if that's
>> worth worrying about.

> We didn't have that before either, did we?

No, so I think it's a pre-existing bug.

> We close it when the sync bit
> changes, but not just if we change say between fsync() and fdatasync().
> Is there any actual reason we'd want to close it?

The point is that if you turn the fsync GUC on or off while using a wal
sync mode that requires supplying an option flag to open(), then really
you ought to close the WAL file and re-open it with the new correct
option flags. The fact that we're not doing that implies that the
effects of a change in fsync might not fully take effect until the next
WAL segment is started. Whether this is worth fixing isn't real clear.

regards, tom lane