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Help with an interesting Postgres question: Why isn't an Index Only Scan used on a partition accessed via the parent table?.
create table t(b) as select true from generate_series(1,5e4);
create index on t(b);
SELECT 50000
CREATE INDEX
create extension if not exists dblink;--spawning a parallel session
select dblink_connect('_','');
select dblink_send_query('_','begin; update t set b=not b; select pg_sleep(11);');
CREATE EXTENSION
| dblink_connect |
|---|
| OK |
SELECT 1
| dblink_send_query |
|---|
| 1 |
SELECT 1
SELECT pid
, l.locktype
, l.relation::regclass
, left(p.query,12) as query
, p.state
, p.wait_event
, l.mode
, l.granted
FROM pg_stat_activity AS p
JOIN pg_locks AS l
USING(pid)
WHERE pid <> pg_backend_pid() --ignore my own query in pg_stat_activity
| pid | locktype | relation | query | state | wait_event | mode | granted |
|---|---|---|---|---|---|---|---|
| 787 | relation | t_b_idx | begin; updat | active | null | RowExclusiveLock | t |
| 787 | relation | t | begin; updat | active | null | RowExclusiveLock | t |
| 787 | virtualxid | null | begin; updat | active | null | ExclusiveLock | t |
| 787 | transactionid | null | begin; updat | active | null | ExclusiveLock | t |
SELECT 4