Re: Using MyDatabaseId in SET_LOCKTAG_APPLY_TRANSACTION
| От | Maxim Orlov |
|---|---|
| Тема | Re: Using MyDatabaseId in SET_LOCKTAG_APPLY_TRANSACTION |
| Дата | |
| Msg-id | CACG=ezZwGXu39-fiBEjJPR8uYv5Ar7QY0F-oxNfFXm_e60jxmQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Using MyDatabaseId in SET_LOCKTAG_APPLY_TRANSACTION (Heikki Linnakangas <hlinnaka@iki.fi>) |
| Ответы |
RE: Using MyDatabaseId in SET_LOCKTAG_APPLY_TRANSACTION
|
| Список | pgsql-hackers |
On Wed, 3 Dec 2025 at 12:38, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
Even with 64-bit XIDs, you can't have transactions older than 2^31 still
running, right? So AFAICS you can continue using 32-bit XID in LOCKTAG.
Actually, I can, and some brave people do just that. Although it is bad
for a number of reasons. The issue is that I can't put on the same page
tuples with XIDs that differ by more than 2^31 using the current design
(with storing the XIDs "base" on the page). That is why I start thinking
for a number of reasons. The issue is that I can't put on the same page
tuples with XIDs that differ by more than 2^31 using the current design
(with storing the XIDs "base" on the page). That is why I start thinking
about "real" 64-bit XIDs.
As for my original question, I think, the reason to have MyDatabaseId
in the LOCKTAG is that it's cheaper to store it in the lock, than try to
get it "on demand" in pg_lock_status() call by invoking
GetSubscription().
Best regards,
Maxim Orlov.
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