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Comment by farsa | Hacker News Reader

Congrats on the progress! What is the behavior of PgDoc if it receives some sort of query it can't currently handle properly? Is there a linter/static analysis tool I can use to evaluate if my query will work?

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The current behavior unfortunately is to just let it through and return an incorrect result. We are adding more checks here and rely heavily on early adopters to have a decent test suite before launching their apps to prod.

That being said, we do have this [1]:

    [general]
    expanded_explain = true

This will modify the output of EXPLAIN queries to return routing decisions made by PgDog. If you see that your query is "direct-to-shard", i.e. goes to only one shard, you can be certain that it'll work as expected. These queries will talk to only one database and don't require us to manipulate the result or assemble results from multiple shards.

For cross-shard queries, you'll need your own integration tests, for now. We'll add checks here shortly. We have a decent CI suite as well, but it doesn't cover everything. Every time we look at that part of the code, we just end up adding more features, like the recent support for LIMIT x OFFSET y (PgDog rewrites it to LIMIT x + y and applies the offset calculation in memory).

We'll get there.

[1]: https://docs.pgdog.dev/features/sharding/explain/

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