diff options
| author | ovalseven8 <8258609+ovalseven8@users.noreply.github.com> | 2018-09-22 15:02:20 +0200 |
|---|---|---|
| committer | Tim Graham <timograham@gmail.com> | 2018-10-03 15:35:20 -0400 |
| commit | 9e5f4bcedb435e05e40720d76678b6266ae20c89 (patch) | |
| tree | 2e1583562c420412e39bd4829aa0902fae2602ba /docs | |
| parent | 173e242d715da1eedce2540f8531b9c446177a16 (diff) | |
[2.1.x] Clarified when QuerySet.select_for_update() locks.
Backport of d093e01ec05f661063507503fdf294eb6ee54dee from master.
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/ref/models/querysets.txt | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/docs/ref/models/querysets.txt b/docs/ref/models/querysets.txt index 98646d5344..609a87097a 100644 --- a/docs/ref/models/querysets.txt +++ b/docs/ref/models/querysets.txt @@ -1664,11 +1664,17 @@ generating a ``SELECT ... FOR UPDATE`` SQL statement on supported databases. For example:: + from django.db import transaction + entries = Entry.objects.select_for_update().filter(author=request.user) + with transaction.atomic(): + for entry in entries: + ... -All matched entries will be locked until the end of the transaction block, -meaning that other transactions will be prevented from changing or acquiring -locks on them. +When the queryset is evaluated (``for entry in entries`` in this case), all +matched entries will be locked until the end of the transaction block, meaning +that other transactions will be prevented from changing or acquiring locks on +them. Usually, if another transaction has already acquired a lock on one of the selected rows, the query will block until the lock is released. If this is |