mirror of
https://github.com/postgres/postgres.git
synced 2026-02-18 10:09:35 -05:00
e3899ffd8b
Specific ever-decreasing insertion patterns could cause successive unbalanced nbtree page splits. Problem cases involve a large group of duplicates to the left, and ever-decreasing insertions to the right. To fix, detect the situation by considering the newitem offset before performing a split using nbtsplitloc.c's "many duplicates" strategy. If the new item was inserted just to the right of our provisional "many duplicates" split point, infer ever-decreasing insertions and fall back on a 50:50 (space delta optimal) split. This seems to barely affect cases that already had acceptable space utilization. An alternative fix also seems possible. Instead of changing nbtsplitloc.c split choice logic, we could instead teach _bt_truncate() to generate a new value for new high keys by interpolating from the lastleft and firstright key values. That would certainly be a more elegant fix, but it isn't suitable for backpatching. Discussion: https://postgr.es/m/CAH2-WznCNvhZpxa__GqAa1fgQ9uYdVc=_apArkW2nc-K3O7_NA@mail.gmail.com Backpatch: 12-, where the nbtree page split enhancements were introduced. |
||
|---|---|---|
| .. | ||
| backend | ||
| bin | ||
| common | ||
| fe_utils | ||
| include | ||
| interfaces | ||
| makefiles | ||
| pl | ||
| port | ||
| template | ||
| test | ||
| timezone | ||
| tools | ||
| tutorial | ||
| .gitignore | ||
| DEVELOPERS | ||
| Makefile | ||
| Makefile.global.in | ||
| Makefile.shlib | ||
| nls-global.mk | ||