How could I do some DB initialization if I still want to use existing Poolable?

[Magicloud]

The problem is about Sqlite. There are some pragmas I want to set. But some of them are not persistent, I need to set them every time I start the Rocket application.

How could I do it in minimal code?

[SergioBenitez]

Many of these options can be set via the URL. What are you trying to set?

Unfortunately, not all drivers allow configuring connections as they're placed in the pool, so exposing an interface to do so is a bit difficult.

[Magicloud]

That'd be "PRAGMA journal_mode = WAL", "PRAGMA synchronous = NORMAL", "PRAGMA foreign_keys = ON", "PRAGMA busy_timeout = 15". As you may know, those are executed as standard SQL query.

[SergioBenitez]

Rocket already executes the following for diesel/SQLite (note that busy_timeout is in milliseconds):

PRAGMA journal_mode = WAL;
PRAGMA busy_timeout = 1000;
PRAGMA foreign_keys = ON;

This isn't documented, it seems. I'd be happy to accept a PR that documents this. So if you're using diesel/sqlite, the only thing that you'd be changing is busy_timeout to something very low and synchronous to NORMAL from FULL.

r2d2 does provide a generic hook for customizing connections, and I'd accept a PR to enable passing on a customizer to r2d2 in rocket_sync_db_pools.

Nevertheless, we'll advocate for using rocket_db_pools, an async variant, in the next RC release in place of rocket_sync_db_pools. deadpool, one of the supported pools, provides no such analog, unfortunately, so we'd need to first have deadpool support this.

[Magicloud]

I am not sure I followed "already executes". By default, Rocket + Diesel usage does not have the WAL file generated. Did you mean directly using SQLite, not via Diesel?

[SergioBenitez]

No, I mean exactly that Rocket executes that SQL for every connection in the Diesel/SQLite database pool:

https://github.com/SergioBenitez/Rocket/blob/7761911847d88a0669e86d503215b3759b27d667/contrib/sync_db_pools/lib/src/poolable.rs#L116-L138

[Magicloud]

Took some time trying to see why mine app does not look like this. Then I noticed this is in 0.5 rc ....