doc: clarify pool sizing

[GradedJestRisk]

Problem

Wiki's entry about pool sizing is great, and I learn many things reading it and watching the video.

However, I get confused because the pool sizing in the entry about does not always relate directly to the number of simultaneous connections a database can handle - which is the actual issue the entry is addressing.

You can have, say, ten instance of an application, each with ten connection in each pool, targeting the same database. The entry talk about "how many connections at the same time in the database", not "how many open connections per pool".

The video use connection pool also, but it looks like a singleton pool (like pgbouncer), not a an applicative pool like HikariCP.

Solution

I replaced connexion pool by active connections in the documentation to clarify.

In the Wiki, I suggest :

• some clarifications about pool type and sizing
• adding a reference to the formula