Disable readstream's reliance on seqscan readahead #532
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Neon doesn't have seqscan detection of its own, so disable read_stream from trying to use that readahead.
knizhnik
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Dec 10, 2024
tristan957
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Dec 10, 2024
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Dec 11, 2024
Neon doesn't have seqscan detection of its own, so stop read_stream from trying to utilize that readahead, and instead make it issue readahead of its own. ## Problem @knizhnik noticed that we didn't issue smgrprefetch[v] calls for seqscans in PG17 due to the move to the read_stream API, which assumes that the underlying IO facilities do seqscan detection for readahead. That is a wrong assumption when Neon is involved, so let's remove the code that applies that assumption. ## Summary of changes Remove the cases where seqscans are detected and prefetch is disabled as a consequence, and instead don't do that detection. PG PR: neondatabase/postgres#532
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Neon doesn't have seqscan detection of its own, so disable read_stream from trying to use that readahead.
Neon PR: neondatabase/neon#9860