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| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2023-09-19 11:53:51 +0300 |
|---|---|---|
| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2023-09-19 11:56:16 +0300 |
| commit | 459439f72892b05b4978959a53d70c5b1d3560a4 (patch) | |
| tree | 4d7ce0b056c6070fc7de91eb711c18dfefaa8ea4 /src | |
| parent | 35e8ba3e54ec01fb705c31061eaeda56ba904354 (diff) | |
| download | postgresql-459439f72892b05b4978959a53d70c5b1d3560a4.tar.gz postgresql-459439f72892b05b4978959a53d70c5b1d3560a4.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
Diffstat (limited to 'src')
| -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 fffdfff6e17..bc22c0a2a96 100644 --- a/src/backend/access/gist/README +++ b/src/backend/access/gist/README @@ -269,10 +269,10 @@ 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 |