diff options
| author | Peter Geoghegan <pg@bowt.ie> | 2020-05-11 11:01:07 -0700 |
|---|---|---|
| committer | Peter Geoghegan <pg@bowt.ie> | 2020-05-11 11:01:07 -0700 |
| commit | 624686abcf87d26fe7c03543c4a54aad2237cb93 (patch) | |
| tree | 14ad51e2395697333d9d84f8ce9a12453aa5f6de /src/backend/access/nbtree/nbtinsert.c | |
| parent | a8be5364ac1678e35029f547632d4002552f943c (diff) | |
Adjust "root of to-be-deleted subtree" function.
Restructure the function that locates the root of the to-be-deleted
subtree during nbtree page deletion. Handle the conditions that make
page deletion unsafe in a slightly more uniform way, and acknowledge the
fact that the behavior with incomplete splits on internal pages is
different (as pointed out in the nbtree README as of commit 35bc0ec7).
Also invent new terminology that avoids ambiguity around which pages are
about to be deleted. Consistently use the term "to-be-deleted subtree",
not the ambiguous term "branch".
We were calling the subtree parent page the "top parent page", but that
was quite misleading. The top parent page usually refers to a page
unlinked from its siblings and marked deleted (during the second stage
of page deletion). There was one kind of top parent page that we merely
removed a downlink from, and another kind of top parent page that we
actually marked deleted. Eliminate the ambiguity by inventing a new
term ("subtree parent page") that refers to the former kind of page
only.
Diffstat (limited to 'src/backend/access/nbtree/nbtinsert.c')
| -rw-r--r-- | src/backend/access/nbtree/nbtinsert.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c index 1c1d4a4bc92..a36b35010e5 100644 --- a/src/backend/access/nbtree/nbtinsert.c +++ b/src/backend/access/nbtree/nbtinsert.c @@ -2278,7 +2278,8 @@ _bt_finish_split(Relation rel, Buffer lbuf, BTStack stack) * stack. For example, the checkingunique _bt_doinsert() case may * have to step right when there are many physical duplicates, and its * scantid forces an insertion to the right of the "first page the - * value could be on". + * value could be on". (This is also relied on by all of our callers + * when dealing with !heapkeyspace indexes.) * * Returns write-locked parent page buffer, or InvalidBuffer if pivot * tuple not found (should not happen). Adjusts bts_blkno & |