Re: Maybe some more low-hanging fruit in the latestCompletedXid patch.
От | Tom Lane |
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Тема | Re: Maybe some more low-hanging fruit in the latestCompletedXid patch. |
Дата | |
Msg-id | 13075.1189442727@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Maybe some more low-hanging fruit in the latestCompletedXid patch. ("Florian G. Pflug" <fgp@phlo.org>) |
Ответы |
Re: Maybe some more low-hanging fruit in the latestCompletedXid
patch.
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Список | pgsql-hackers |
"Florian G. Pflug" <fgp@phlo.org> writes: > Currently, we do not assume that either the childXids array, nor > the xid cache in the proc array are sorted by ascending xid order. > I believe that we could simplify the code, further reduce the locking > requirements, and enabled a transaction to de-overflow it's xid cache > if we assume that those arrays are in ascending xid order. "de-overflowing" the cache sounds completely unsafe, as other backends need that state to determine whether they need to look into pg_subtrans. I still don't believe you can avoid taking exclusive lock, either; your argument here did not address latestCompletedXid. But the main point remains this: there is no evidence whatsoever that these code paths are sufficiently performance-critical to be worth speeding up by making the code more fragile. regards, tom lane
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