Re: locks within select

2021-12-14 Thread Marc Millas
Excellent ! thanks a lot, it was exactly what I was looking for. Marc MILLAS Senior Architect +33607850334 www.mokadb.com On Tue, Dec 14, 2021 at 6:14 PM Laurenz Albe wrote: > On Tue, 2021-12-14 at 13:38 +0100, Marc Millas wrote: > > but... when you do setup a streaming replication, there is,

Re: locks within select

2021-12-14 Thread Laurenz Albe
On Tue, 2021-12-14 at 13:38 +0100, Marc Millas wrote: > but... when you do setup a streaming replication, there is, in > postgresql.conf, a variable:  > max_standby_streaming_delay = 30s # max delay before canceling queries when > reading streaming WAL; > > as the secondary is, by nature, read o

Re: locks within select

2021-12-14 Thread David G. Johnston
On Tuesday, December 14, 2021, Marc Millas wrote: > > > So, if its not a locking scheme, what can block hundreds of transaction to > get to the secondary ??? > The transactions are present on the secondary. It just realizes that applying them may cause problems (think drop table or truncate) and

Re: locks within select

2021-12-14 Thread Marc Millas
I did read this, before asking my question... but... when you do setup a streaming replication, there is, in postgresql.conf, a variable: max_standby_streaming_delay = 30s # max delay before canceling queries when reading streaming WAL; as the secondary is, by nature, read only, I was wondering w

Re: locks within select

2021-12-13 Thread David G. Johnston
On Monday, December 13, 2021, Marc Millas wrote: > > I was wondering if for example, within a join, some kind of lock may be > acquired so that the dataset concerned is not changed during execution ? > (for example a delete then autovacuum ??) > Read this primer on MVCC from the docs: https://ww