POOL_SIZE config var

[RobStallion]

POOL_SIZE is a variable that is set in the config files. Phoenix seems to give it a default value of 10 always.

However I was working on an application that had been deployed to heroku and the POOL_SIZE variable was set to 18. Everything seemed to work as expected until we tried to run a seed file.

When we were running the seed file we were getting the following error

Postgrex.Protocol (#PID<0.259.0>) failed to connect: ** (Postgrex.Error) FATAL 53300 (too_many_connections): too many connections for role.

I noticed that the phoenix default was 10 so updated that value on heroku and and ran the seed file again, but this time it worked.

Opening this issue so that I can document anything I learn about how POOL_SIZE works (in general and on heroku) here but if anyone has an knowledge please comment.