| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com> |
| Cc: | Alexander Korotkov <aekorotkov(at)gmail(dot)com>, Melanie Plageman <melanieplageman(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Japin Li <japinli(at)hotmail(dot)com>, Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Michael Paquier <michael(at)paquier(dot)xyz>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com> |
| Subject: | Re: Table AM Interface Enhancements |
| Date: | 2024-04-15 18:08:51 |
| Message-ID: | CA+TgmobU6u6wLtxBwwrMdapVooUSt1q3CEG0n=F3SqnVQtWMRg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Apr 15, 2024 at 12:37 PM Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com> wrote:
> In my understanding, the downside of 041b96802ef is bringing read_stream* things from being heap-only-related up to the level of acquire_sample_rows() that is not supposed to be tied to heap. And changing *_analyze_next_block() function signature to use ReadStream explicitly in the signature.
I don't think that really clarifies anything. The ReadStream is
basically just acting as a wrapper for a stream of block numbers, and
the API took a BlockNumber before. So why does it make any difference?
If I understand correctly, Alexander thinks that, before 041b96802ef,
the block number didn't necessarily have to be the physical block
number on disk, but could instead be any 32-bit quantity that the
table AM wanted to pack into the block number. But I don't think
that's true, because acquire_sample_rows() was already passing those
block numbers to PrefetchBuffer(), which already requires physical
block numbers.
--
Robert Haas
EDB: http://www.enterprisedb.com
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