mirror of
https://github.com/postgres/postgres.git
synced 2026-02-26 11:21:03 -05:00
46e3a16b05
underneath the Limit node, not atop it. This fixes the old problem that such a query might unexpectedly return fewer rows than the LIMIT says, due to LockRows discarding updated rows. There is a related problem that LockRows might destroy the sort ordering produced by earlier steps; but fixing that by pushing LockRows below Sort would create serious performance problems that are unjustified in many real-world applications, as well as potential deadlock problems from locking many more rows than expected. Instead, keep the present semantics of applying FOR UPDATE after ORDER BY within a single query level; but allow the user to specify the other way by writing FOR UPDATE in a sub-select. To make that work, track whether FOR UPDATE appeared explicitly in sub-selects or got pushed down from the parent, and don't flatten a sub-select that contained an explicit FOR UPDATE. |
||
|---|---|---|
| .. | ||
| adt | ||
| cache | ||
| error | ||
| fmgr | ||
| hash | ||
| init | ||
| mb | ||
| misc | ||
| mmgr | ||
| resowner | ||
| sort | ||
| time | ||
| .cvsignore | ||
| Gen_dummy_probes.sed | ||
| Gen_fmgrtab.pl | ||
| Gen_fmgrtab.sh | ||
| Makefile | ||
| probes.d | ||