Conversation
1. Use deferred BEGIN (SHARED lock) instead of BEGIN IMMEDIATE (RESERVED lock) for read-only wrapper transactions (SHOW, DESCRIBE). 2. Skip the wrapper transaction entirely for SELECT statements. Fixes: #318
bgrgicak
reviewed
Apr 16, 2026
| * [GRAMMAR] | ||
| * simpleStatement: selectStatement | showStatement | utilityStatement | ... | ||
| */ | ||
| $statement_node = $child_node->get_first_child_node(); |
Collaborator
There was a problem hiding this comment.
Should we wrap this in if ( null === $child_node ) because it seems like $child_node can be null?
Member
Author
There was a problem hiding this comment.
👍 At this point in the AST, there is probably always a child node, but it's a good idea to add it, also for consistency with the code above. Fixed in 14dc77a.
bgrgicak
reviewed
Apr 16, 2026
| /** | ||
| * Tests for concurrent access to the same SQLite database file. | ||
| */ | ||
| class WP_SQLite_Driver_Concurrency_Tests extends TestCase { |
Collaborator
There was a problem hiding this comment.
Should we add a test for showStatement queries to confirm that it uses the correct BEGIN?
Member
Author
There was a problem hiding this comment.
👍 Added tests for SHOW and DESCRIBE in c559b3a.
Member
Author
|
@bgrgicak Thanks! Addressed both issues. |
Pin BEGIN IMMEDIATE for write statements (INSERT, UPDATE, DELETE, REPLACE, CREATE/ALTER/DROP/TRUNCATE TABLE) so a future regression that accidentally flags a write as read-only — downgrading the lock to a deferred BEGIN — is caught immediately. Mirror the existing SELECT two-connection contention test for SHOW and DESCRIBE, proving they succeed under a concurrent RESERVED lock instead of only asserting the logged BEGIN string. Factor out a couple of small helpers to remove the repeated driver and query-logger setup boilerplate.
bgrgicak
approved these changes
Apr 17, 2026
Merged
JanJakes
added a commit
that referenced
this pull request
Apr 17, 2026
## Release `3.0.0-rc.1` Version bump and changelog update for release `3.0.0-rc.1`. **Changelog draft:** * Improve concurrent database access ([#361](#361)) * Remove legacy SQLite driver ([#358](#358)) **Full changelog:** v2.2.23...release/v3.0.0-rc.1 ## Next steps 1. **Review** the changes in this pull request. 2. **Push** any additional edits to this branch (`release/v3.0.0-rc.1`). 3. **Merge** this pull request to complete the release. Merging will automatically build the plugin ZIP and create a [GitHub release](https://github.com/WordPress/sqlite-database-integration/releases). > [!NOTE] > This is a **pre-release**. It will not be deployed to [WordPress.org](https://wordpress.org/plugins/sqlite-database-integration/).
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
Reduces lock contention under concurrent access by avoiding unnecessary write locks for read-only queries.
BEGIN/COMMITneeded.BEGINfor other read-only wrapper transactions. SHOW and DESCRIBE queries still use a wrapper transaction (they may translate to multiple SQLite queries), but now use a deferredBEGIN(SHARED lock) instead ofBEGIN IMMEDIATE(RESERVED lock).Background
The wrapper transaction previously used
BEGIN IMMEDIATEfor all queries, including read-only SELECTs. This acquired a RESERVED (write) lock on every query — but SQLite only allows one RESERVED lock at a time. Under concurrent load (e.g., multiple PHP-FPM workers handling requests simultaneously), all processes competed for the single write lock. When the 10-second busy timeout was exceeded, SQLite returnedSQLITE_BUSY("database is locked", error 5).SHARED locks, acquired by a deferred
BEGIN, are compatible with RESERVED locks — multiple readers can proceed concurrently alongside an active writer.Fixes #318