Re: [PATCHES] Full page writes improvement, code update

Simon;
Tom;

Koichi is writing.

Your question is how to determine WAL record generated between
pg_start_backup and pg_stop_backup and here's an answer.

XLogInsert( ) already has a logic to determine if inserting WAL record
is between pg_start_backup and pg_stop_backup. Currently it is used
to remove full_page_writes when full_page_writes=off. We can use
this to mark WAL records. We have one bit not used in WAL record
header, the last bit of xl_info, where upper four bits are used to
indicate the resource manager and three of the rest are used to
indicate number of full page writes included in the record.

So in my proposal, this unused bit is used to mark that full page
writes must not be removed at offline optimization by pg_complesslog.

Sorry I didn't have mailing list capability from home and have just
completed my subscription from
home. I had to create new thread to continue my post. Sorry for confusion.

Please refer to the original thread about this discussion.

Best Regards;

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Koichi Suzuki