Re: pg_xlogdump fails to handle WAL file with multi-page XLP_FIRST_IS_CONTRECORD data
От | Pavan Deolasee |
---|---|
Тема | Re: pg_xlogdump fails to handle WAL file with multi-page XLP_FIRST_IS_CONTRECORD data |
Дата | |
Msg-id | CABOikdM2f03191gO9GSHLHe7SBCtAzRaSzbX-ac0co5+p9VcMg@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: pg_xlogdump fails to handle WAL file with multi-page XLP_FIRST_IS_CONTRECORD data (Craig Ringer <craig@2ndquadrant.com>) |
Ответы |
Re: pg_xlogdump fails to handle WAL file with multi-page
XLP_FIRST_IS_CONTRECORD data
|
Список | pgsql-hackers |
On Thu, Mar 31, 2016 at 6:27 AM, Craig Ringer <craig@2ndquadrant.com> wrote:
Shame that I can't find the sql file used to create the problematic WAL segment. But this is what I did.Can you describe the process used to generate the sample WAL segment?
I wrote a plpgsql function which inserts rows in a loop, every time checking if the remaining space in the WAL segment has fallen to less than couple of hundred bytes. Of course, I used pg_settings to get the WAL segment size, WAL page size and pg_current_xlog_insert_location() to correctly compute remaining bytes in the WAL segment. At this point, do a non-HOT update, preferably to table which is already fully vacuumed and CHECKPOINTed to avoid getting any other WAL records in between. Assuming FPW is turned ON, the UPDATE should generate enough WAL to cross over the first page in the new WAL segment.
Let me know if you would like to me to put together a sql based on this description.
Thanks,
Pavan
Pavan Deolasee http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
PostgreSQL Development, 24x7 Support, Training & Services
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