drvgettable(): fix leaked SQLite statement / persistent lock when SQL_ATTR_MAX_ROWS cap is hit - #22
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… is hit If a statement's row-count cap (SQL_ATTR_MAX_ROWS) is reached before the result set is exhausted, the fetch loop broke out without finalizing or resetting the active sqlite3_stmt. The very next outer- loop iteration then overwrote the only reference to it (tres.stmt = NULL), orphaning a still-open statement that keeps holding its SQLite lock for as long as the connection stays open -- blocking every other process from writing to the file, independent of any BEGIN/COMMIT or autocommit state. Route the max_rows early-exit through the same finalize-or-reset cleanup already used by the loop's normal completion path instead of skipping it, so the statement (and its lock) is released immediately when the cap is hit.
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If a statement's row-count cap (SQL_ATTR_MAX_ROWS) is reached before the result set is exhausted, the fetch loop broke out without finalizing or resetting the active sqlite3_stmt. The very next outer- loop iteration then overwrote the only reference to it (tres.stmt = NULL), orphaning a still-open statement that keeps holding its SQLite lock for as long as the connection stays open -- blocking every other process from writing to the file, independent of any BEGIN/COMMIT or autocommit state.
Route the max_rows early-exit through the same finalize-or-reset cleanup already used by the loop's normal completion path instead of skipping it, so the statement (and its lock) is released immediately when the cap is hit.
As a result of this, some applications had issues with concurrent access which this PR now fixes.
The motivation for this PR was to fix a compatibility with Altium which is discussed here:
https://stackoverflow.com/questions/45269190/sqlite-odbc-driver-and-database-locking