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| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2019-07-24 20:24:05 +0300 |
|---|---|---|
| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2019-07-24 20:24:05 +0300 |
| commit | 9eb5607e69933f0a88b6774d1ba728f27afdbd3d (patch) | |
| tree | 26fb607fb0d1ce8aa78dec122ff027d5fe9a29e1 /src/backend/access/gist/gistget.c | |
| parent | 1a721248f3899ccf8c0c7512b91d8458f2394aeb (diff) | |
| download | postgresql-9eb5607e69933f0a88b6774d1ba728f27afdbd3d.tar.gz postgresql-9eb5607e69933f0a88b6774d1ba728f27afdbd3d.zip | |
Refactor checks for deleted GiST pages.
The explicit check in gistScanPage() isn't currently really necessary, as
a deleted page is always empty, so the loop would fall through without
doing anything, anyway. But it's a marginal optimization, and it gives a
nice place to attach a comment to explain how it works.
Backpatch to v12, where GiST page deletion was introduced.
Reviewed-by: Andrey Borodin
Discussion: https://www.postgresql.org/message-id/835A15A5-F1B4-4446-A711-BF48357EB602%40yandex-team.ru
Diffstat (limited to 'src/backend/access/gist/gistget.c')
| -rw-r--r-- | src/backend/access/gist/gistget.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/src/backend/access/gist/gistget.c b/src/backend/access/gist/gistget.c index 46d08e06350..4e0c500a22e 100644 --- a/src/backend/access/gist/gistget.c +++ b/src/backend/access/gist/gistget.c @@ -377,6 +377,20 @@ gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem, double *myDistances, MemoryContextSwitchTo(oldcxt); } + /* + * Check if the page was deleted after we saw the downlink. There's + * nothing of interest on a deleted page. Note that we must do this + * after checking the NSN for concurrent splits! It's possible that + * the page originally contained some tuples that are visible to us, + * but was split so that all the visible tuples were moved to another + * page, and then this page was deleted. + */ + if (GistPageIsDeleted(page)) + { + UnlockReleaseBuffer(buffer); + return; + } + so->nPageData = so->curPageData = 0; scan->xs_hitup = NULL; /* might point into pageDataCxt */ if (so->pageDataCxt) |