On 08/05/2019 01:31, Heikki Linnakangas wrote:
On 02/05/2019 10:37, Heikki Linnakangas wrote:
On 29/04/2019 16:16, Anastasia Lubennikova wrote:
In previous emails, I have sent two patches with test and bugfix (see
attached).
After Heikki shared his concerns, I've rechecked the algorithm and
haven't found any potential error.
So, if other hackers are agreed with my reasoning, the suggested fix is
sufficient and can be committed.
I still believe there is a problem with grandparent splits with this.
I'll try to construct a test case later this week, unless you manage to
create one before that.
Here you go. If you apply the two patches from
https://www.postgresql.org/message-id/5d48ce28-34cf-9b03-5d42-dbd5457926bf%40postgrespro.ru,
and run the attached script, it will print out something like this:
postgres=# \i grandparent.sql
DROP TABLE
CREATE TABLE
INSERT 0 150000
CREATE INDEX
psql:grandparent.sql:27: NOTICE: working on 10000
psql:grandparent.sql:27: NOTICE: working on 20000
psql:grandparent.sql:27: NOTICE: working on 30000
psql:grandparent.sql:27: NOTICE: working on 40000
psql:grandparent.sql:27: NOTICE: working on 50000
psql:grandparent.sql:27: NOTICE: working on 60000
psql:grandparent.sql:27: NOTICE: working on 70000
psql:grandparent.sql:27: NOTICE: working on 80000
psql:grandparent.sql:27: NOTICE: working on 90000
psql:grandparent.sql:27: NOTICE: working on 100000
psql:grandparent.sql:27: NOTICE: working on 110000
psql:grandparent.sql:27: NOTICE: failed for 114034
psql:grandparent.sql:27: NOTICE: working on 120000
DO
That "failed for 114034" should not happen.
Fortunately, that's not too hard to fix. We just need to arrange things
so that the "retry_from_parent" flag also gets set for the grandparent,
when the grandparent is split. Like in the attached patch.
I hear no objections, so pushed that. But if you have a chance to review
this later, just to double-check, I'd still appreciate that.
- Heikki
