prefill after switch-to

[fluca1978]

Don't know if this is a valuable feature, but with 1.5 when I do a switch-to and/or a reset-server the prefill seems to be dropped.
I mean, when I start pgagroal the "initial" connections from pgagroal_databases.conf are established. When I do a switch-to to another server, the new server does not get the "initial" connection number but only the "minimum".
The same when I come back with another switch-to the original server.
Is there a reason or should pgagroal honor the "initial" connection every time a server is changed as primary?

[jesperpedersen]

I agree. switch-to should trigger prefill, since the connections on the previous primary should go into graceful

[fluca1978]

The problem, at least in my configuration, is when the old server is flushed: https://github.com/agroal/pgagroal/blob/master/src/libpgagroal/pool.c#L852.
There are however other places where the prefill is invoked with a false argument, that measn "use min values", while we would like to get with "initial" values.
I think there is the need to understand if pgagroal_flush_server has been invoked by a flush command, in which case it is correct to set connections to the minimum, or by a switch-to, in such case it should be prefil with "initial".
Adding a parameter to the pgagroal_flush_server?

[jesperpedersen]

That is likely one way to do it

[fluca1978]

I could spend some time and effort on this, if you believe there are no other tricks and dangerous zones...

[jesperpedersen]

Go for it !

[jesperpedersen]

There is a bit more to it.

The old primary should never prefill no matter what the min_size is - in the case of switch-to.

[fluca1978]

The old primary should never prefill no matter what the min_size is - in the case of switch-to.

I'm going to work on this starting from the next week, but in the meantime I'm reasoning about this.
When I switch-to a new server, the old primary will be graceful and the new one is going to get prefilled, and this is the problem I'm going to try to fix. If I then switch-to back to the old primary, why should I don't prefill it?

[jesperpedersen]

In relation to the switch-to.

pgagroal_databases.conf

mydb myuser 100 20 10

Initial

host1(20)(Primary)
host2(0)(Not init)

switch-to(host2)

host1(0)(Not init)
host2(20)(Primary)

switch-to(host1)

host1(20)(Primary)
host2(0)(Not init)

So, I think we agree, right ?

[fluca1978]

Yes, it was what I was thinking about.