libsql-sqlite3: Fix problem with disappearing WAL frames #1852
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We have a problem with WAL API where in some scenarios, we seem to lose WAL frames that were already applied. However, inspecting the external WAL frame, the sync mechanics work fine and the problem is in SQLite's in-memory state. As it turnws out, the sqlite3PagerWalBeginCommit() function first begins a read transaction and then upgrades it to a write transaction. However, sqlite3PagerWalEndCommit() only ends the write transaction and therefore leaves the pager in READER state. Let's call pager_unlock() to switch to OPEN stte, fixing the issue of disappearing frames.
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sivukhin
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Nov 28, 2024
We need to reset the pager in sqlite3PagerWalEndCommit() to make sure page cache is invalidated after injecting frames to WAL to ensure they're visible.
We need to make sure we test a case where page cache is non-empty.
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We have a problem with WAL API where in some scenarios, we seem to lose WAL frames that were already applied. However, inspecting the external WAL frame, the sync mechanics work fine and the problem is in SQLite's in-memory state.