Message-ID: <8330278b-9615-4030-8626-51ce714a7f54@enterprisedb.com>
Date: Fri, 29 Mar 2024 12:05:15 +0100
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Subject: Re: BitmapHeapScan streaming read user and prelim refactoring
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Melanie Plageman <melanieplageman@gmail.com>,
 Heikki Linnakangas <hlinnaka@iki.fi>, Andres Freund <andres@anarazel.de>,
 Pg Hackers <pgsql-hackers@postgresql.org>,
 Nazir Bilal Yavuz <byavuz81@gmail.com>
References: <5a172d1e-d69c-409a-b1fa-6521214c81c2@iki.fi>
 <20240323002211.on5vb5ulk6lsdb2u@liskov>
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 <e472f0cb-bdcd-4fe9-9bf6-23a041dedc5d@enterprisedb.com>
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 <58fa8dd3-a49b-4774-a9c4-7422ba8bc698@enterprisedb.com>
 <CAAKRu_Yzm6ae-Njj9DHwk0bbFC6QpzbjB=aY39civtpsUYgORQ@mail.gmail.com>
 <358c737e-772c-40dd-9ecf-35b0c05828cd@enterprisedb.com>
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 <20240325160709.qjo6txzu6zjxzkqy@liskov>
 <20240327193750.3mlcmzqondpj27xe@liskov>
 <7e98781c-34e0-4c02-8e5b-0500aa074271@enterprisedb.com>
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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
In-Reply-To: <CA+hUKGJtm_gkmW_h_02-Q9ZRcG3yOx2uzVqbCTfz7YPnTfs+DA@mail.gmail.com>
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On 3/29/24 02:12, Thomas Munro wrote:
> On Fri, Mar 29, 2024 at 10:43 AM Tomas Vondra
> <tomas.vondra@enterprisedb.com> wrote:
>> I think there's some sort of bug, triggering this assert in heapam
>>
>>   Assert(BufferGetBlockNumber(hscan->rs_cbuf) == tbmres->blockno);
> 
> Thanks for the repro.  I can't seem to reproduce it (still trying) but
> I assume this is with Melanie's v11 patch set which had
> v11-0016-v10-Read-Stream-API.patch.
> 
> Would you mind removing that commit and instead applying the v13
> stream_read.c patches[1]?  v10 stream_read.c was a little confused
> about random I/O combining, which I fixed with a small adjustment to
> the conditions for the "if" statement right at the end of
> read_stream_look_ahead().  Sorry about that.  The fixed version, with
> eic=4, with your test query using WHERE a < a, ends its scan with:
> 

I'll give that a try. Unfortunately unfortunately the v11 still has the
problem I reported about a week ago:

  ERROR:  prefetch and main iterators are out of sync

So I can't run the full benchmarks :-( but master vs. streaming read API
should work, I think.

regards

-- 
Tomas Vondra
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