On 1/28/19 6:07 AM, Thomas Poty wrote:
Hello ,
In PG10, when I am altering a sequence, i see 2 locks in pg_locks
matching my sequence:
a RowExclusiveLock
and a ShareRowExclusiveLock
My question is Why 2 locks?
Someone on irc said it was for catalog but i am no sure because
pg_locks.relationid is the same for the 2 locks.
At the same time, If I am trying to call nextval with an othersession,
the session wants to get a RowExclusiveLock on the sequence.
So, to me, the lock ShareRowExclusiveLock is when the sequence is beeing
altered.
And the RowExclusiveLock is for concurent access between alter/drop
sequence and nextval/setval/curval/lastval.
Documentation seems not talking about this...
(https://www.postgresql.org/docs/10/explicit-locking.html) Maybe should
I open a ticket?
A sequence, for practical purposes, is a table. So in the above
substitute TABLE with SEQUENCE:
Thanks
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
