How safe is sqlx compile time checks?

[finlaydotb]

If I understand correctly, it is possible for sqlx to do a form of compile time verification of queries. And the way it does this, is at compile time, it connects to the database using DATABASE_URL env variable and performs some checks against the database.

My question is, how does sqlx ensure safety? How does sqlx ensures that the verification does not actually mutates the database? I mean how does it handle checks for queries like delete, insert, update etc?

[mehcode]

SQLx does not actually run the queries. Primarily SQLx issues the PREPARE-equivalent command to the database (via its protocol as this is not exposed in SQL) and receives the type information for the query from the database. This is the same information that something like DataGrip (from Jetbrains) uses to label and format the columns when its executing its queries. I would still say that even if its relatively safe, do not use SQLx on a production database. We recommend using SQL migrations so you can easily spin up a facsimile locally and run SQLx against that.