| From: | Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com> |
|---|---|
| To: | Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, masao(dot)fujii(at)oss(dot)nttdata(dot)com, Ken Kato <katouknl(at)oss(dot)nttdata(dot)com>, Aleksander Alekseev <aleksander(at)timescale(dot)com> |
| Subject: | Is monotonous xid8 is a right way to do? |
| Date: | 2022-04-01 12:13:17 |
| Message-ID: | CALT9ZEFkKtxqa2=53Rptc+TWD6ovMx7ACWn3tkdZ2r4j1NHKbg@mail.gmail.com |
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| Lists: | pgsql-hackers |
Hi hackers!
Now we have two data types xid and xid8. The first one (xid) makes a
numeric ring, and xid8 are monotonous.
As per [1] "Unlike xid values, xid8 values increase strictly monotonically
and cannot be reused in the lifetime of a database cluster."
As a consequence of [1] xid8 can have min/max functions (committed in [2]),
which xid can not have.
When working on 64xid patch [3] we assume that even 64xid's technically can
be wraparound-ed, although it's very much unlikely. I wonder what is
expected to be with xid8 values at this (unlikely) 64xid wraparound?
What do you think about this? Wouldn't it be better to change xid8 to form
a numeric ring like xid? I think it is necessary for any
64-wraparound-enabled implementation of 64xids.
Please feel free to share your thoughts.
[1] https://www.postgresql.org/docs/current/datatype-oid.html
[2]
https://www.postgresql.org/message-id/flat/47d77b18c44f87f8222c4c7a3e2dee6b%40oss.nttdata.com
[3]
https://www.postgresql.org/message-id/flat/CACG%3DezZe1NQSCnfHOr78AtAZxJZeCvxrts0ygrxYwe%3DpyyjVWA%40mail.gmail.com
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