I just checked for hash collisions with the following query today:
SELECT COUNT(*), hashtextextended(key, 0) FROM
(
SELECT key FROM table1
UNION
SELECT key FROM table2
UNION
...
) keys (key)
GROUP BY hashtextextended(key, 0)
HAVING COUNT(*) > 1
Where table1, table2, ... are all the tables we are acquire keys from to
use for the mentioned query.
Sadly, no results were returned. Thus, I can rule out hash collisions.
Any other thoughts? Here is an error log from the JDBC driver:
org.postgresql.util.PSQLException: ERROR: deadlock detected Detail:
Process 60780 waits for ExclusiveLock on advisory lock
[24605,3030106527,494580150,1]; blocked by process 65280.
Process 65280 waits for ExclusiveLock on advisory lock
[24605,1321834016,1311356115,1]; blocked by process 60780.
On 2/11/26 23:49, Tom Lane wrote:
Nico Heller<[email protected]> writes:
So it would probably be better to ORDER BY the hashtextended result
instead of :keysToLock, right?
Yeah, that seems like it'd work, if you have no other dependencies
on the locking order.
regards, tom lane
