Hard coded sqlite connection size limits limits concurrency and varies with password presence #1604

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opened 2026-02-06 10:17:07 +00:00 by thesimplekid · 0 comments

thesimplekid commented

2026-02-06 10:17:07 +00:00

(Migrated from github.com)

Since the database is configured with pragma journal_mode = WAL (Write-Ahead Logging), SQLite is capable of handling multiple concurrent readers. Limiting the pool to a single connection for unencrypted databases serializes all operations, negating the performance benefits of WAL mode, while encrypted databases arbitrarily receive a higher limit.

I think we should set this to some more reasonable number and in the mint we could even reuse the connection limit setting we have for psgl.

github.com/cashubtc/cdk@3e6474bbd9/crates/cdk-sqlite/src/common.rs (L24-L31)

The test restore seems to often fail with timeout issues in ci, I am wondering if having more readers would help this?

The current SQLite connection sets the max number of connections based on the presence of a password. I don't see why this is the case having a password should not determine the number of connections we have. Since the database is configured with pragma journal_mode = WAL (Write-Ahead Logging), SQLite is capable of handling multiple concurrent readers. Limiting the pool to a single connection for unencrypted databases serializes all operations, negating the performance benefits of WAL mode, while encrypted databases arbitrarily receive a higher limit. I think we should set this to some more reasonable number and in the mint we could even reuse the connection limit setting we have for psgl. https://github.com/cashubtc/cdk/blob/3e6474bbd9f2e8cd69ec7a8879de8f599007c081/crates/cdk-sqlite/src/common.rs#L24-L31 The test restore seems to often fail with timeout issues in ci, I am wondering if having more readers would help this?

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cashubtc/cdk#1604

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