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Serve NONE queries always after restart#2330

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otoolep wants to merge 8 commits intomasterfrom
read-on-restart
Open

Serve NONE queries always after restart#2330
otoolep wants to merge 8 commits intomasterfrom
read-on-restart

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@otoolep otoolep commented Sep 15, 2025

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Summary of Changes

Hello @otoolep, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refines the rqlite store's operational behavior during node restarts. It introduces a mechanism that allows a restarted node to fulfill NONE consistency level queries using its local database, even before it fully re-establishes its connection to the cluster. This is achieved by deferring the deletion and subsequent rebuilding of the SQLite database until the node actively participates in the Raft consensus by applying log entries, thereby balancing immediate read availability with eventual data consistency.

Highlights

  • Enhanced Restart Behavior: Nodes can now serve NONE consistency queries immediately after restarting, even if they are not yet connected to the cluster, improving availability for local reads.
  • Conditional Database Deletion: The existing SQLite database is no longer immediately deleted upon node startup. Instead, its deletion and rebuilding from the Raft log are deferred until the node begins applying log entries, ensuring data consistency when it rejoins the cluster.
  • New Test Case: A new multi-node test (Test_MultiNode_RestartNoQuorum) has been added to validate the behavior of NONE queries after restart in a disconnected state and subsequent cluster re-engagement.
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Code Review

This pull request introduces a useful feature that allows a node to serve NONE consistency queries after a restart, even before it has formed a quorum with the cluster. This is achieved by preserving the on-disk SQLite file during startup. The logic to then delete this file upon the first new Raft log application is sound. However, there's a critical issue in the implementation: the flag dbDeleteNeeded that controls this deletion is never set, which would lead to an inconsistent database state if the node later rejoins the cluster and applies new logs. A new test is included which validates the primary goal, but it doesn't cover the scenario that would expose this bug. I've provided a comment with a fix for this critical issue.

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