Skip to content

Disable readstream's reliance on seqscan readahead #532

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
MMeent merged 1 commit into from
Dec 10, 2024
Merged

Disable readstream's reliance on seqscan readahead #532

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 8 additions & 1 deletion src/backend/storage/aio/read_stream.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -224,9 +224,10 @@ read_stream_start_pending_read(ReadStream *stream, bool suppress_advice)
* If advice hasn't been suppressed, this system supports it, and this
* isn't a strictly sequential pattern, then we'll issue advice.
*/
/* NEON: disabled seqscan detection */
if (!suppress_advice &&
stream->advice_enabled &&
stream->pending_read_blocknum != stream->seq_blocknum)
true /* stream->pending_read_blocknum != stream->seq_blocknum */)
flags = READ_BUFFERS_ISSUE_ADVICE;
else
flags = 0;
Expand Down Expand Up @@ -391,6 +392,12 @@ read_stream_begin_relation(int flags,
Oid tablespace_id;
SMgrRelation smgr;

/*
* NEON: We don't benefit from the OS readahead that callers with
* READ_STREAM_SEQUENTIAL expect, so we disable that flag.
*/
flags &= ~READ_STREAM_SEQUENTIAL;

smgr = RelationGetSmgr(rel);

/*
Expand Down