| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Justin <zzzzz(dot)graf(at)gmail(dot)com> |
| Cc: | Daniel Verite <daniel(at)manitou-mail(dot)org>, shalini(at)saralweb(dot)com, Rene Romero Benavides <rene(dot)romero(dot)b(at)gmail(dot)com>, Postgres General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Tuple concurrency issue in large objects |
| Date: | 2019-12-18 16:12:40 |
| Message-ID: | 5126.1576685560@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
Justin <zzzzz(dot)graf(at)gmail(dot)com> writes:
> I have a question reading through this email chain. Does Large Objects
> table using these functions work like normal MVCC where there can be two
> versions of a large object in pg_largeobject .
Yes, otherwise you could never roll back a transaction that'd modified
a large object.
> My gut says no as
> moving/copying potentially 4 TB of data would kill any IO.
Well, it's done on a per-chunk basis (normally about 2K per chunk),
so you won't do that much I/O unless you're changing all of a 4TB
object.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Kaijiang Chen | 2019-12-18 16:14:26 | Re: Fwd: weird long time query |
| Previous Message | Justin | 2019-12-18 15:37:08 | Re: Tuple concurrency issue in large objects |