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| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2023-09-19 11:53:51 +0300 |
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| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2023-09-19 11:56:10 +0300 |
| commit | bd7a18e70714bd57c1375a93eb2e64378dbc7d99 (patch) | |
| tree | 50156c6f4dc438cc4bb22cd16e80d45c79f3b47c | |
| parent | 9e0ce80f3d0c217c33034984fce022a329d8961f (diff) | |
| download | postgresql-bd7a18e70714bd57c1375a93eb2e64378dbc7d99.tar.gz postgresql-bd7a18e70714bd57c1375a93eb2e64378dbc7d99.zip | |
Fix GiST README's explanation of the NSN cross-check.
The text got the condition backwards, it's "NSN > LSN", not "NSN < LSN".
While we're at it, expand it a little for clarity.
Reviewed-by: Daniel Gustafsson
Discussion: https://www.postgresql.org/message-id/4cb46e18-e688-524a-0f73-b1f03ed5d6ee@iki.fi
| -rw-r--r-- | src/backend/access/gist/README | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/src/backend/access/gist/README b/src/backend/access/gist/README index efb2730e181..8015ff19f05 100644 --- a/src/backend/access/gist/README +++ b/src/backend/access/gist/README @@ -271,10 +271,10 @@ should be visited too. When split inserts the downlink to the parent, it clears the F_FOLLOW_RIGHT flag in the child, and sets the NSN field in the child page header to match the LSN of the insertion on the parent. If the F_FOLLOW_RIGHT flag is not set, a scan compares the NSN on the child and the -LSN it saw in the parent. If NSN < LSN, the scan looked at the parent page -before the downlink was inserted, so it should follow the rightlink. Otherwise -the scan saw the downlink in the parent page, and will/did follow that as -usual. +LSN it saw in the parent. If the child's NSN is greater than the LSN seen on +the parent, the scan looked at the parent page before the downlink was +inserted, so it should follow the rightlink. Otherwise the scan saw the +downlink in the parent page, and will/did follow that as usual. A scan can't normally see a page with the F_FOLLOW_RIGHT flag set, because a page split keeps the child pages locked until the downlink has been inserted |