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…M errors on readonly DB
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Please add a test case. You can refer to the devguide for how to do that.
Misc/NEWS.d/next/Library/2025-06-16-15-00-13.gh-issue-135386.lNrxLc.rst Outdated Show resolved Hide resolved
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707f4a3 to 779faf2 Compare 779faf2 to 3e3a3ba Compare No need to force-push, we squash at the end. |
Got it, thanks for the reminder! |
FYI, tests are failing on Windows. |
Thanks for the suggestion. I've skipped the test on Windows using |
| if flag == "ro": | ||
| # Add immutable=1 to allow read-only SQLite access even if wal/shm missing | ||
| uri = f"{uri}?mode={flag}&immutable=1" | ||
| else: | ||
| uri = f"{uri}?mode={flag}" |
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| if flag == "ro": | |
| # Add immutable=1 to allow read-only SQLite access even if wal/shm missing | |
| uri = f"{uri}?mode={flag}&immutable=1" | |
| else: | |
| uri = f"{uri}?mode={flag}" | |
| uri = f"{uri}?mode={flag}" | |
| if flag == "ro": | |
| # Add immutable=1 to allow read-only SQLite access even if wal/shm missing | |
| uri += "&immutable=1" |
| # This is an optimization only; it's ok if it fails. | ||
| with suppress(sqlite3.OperationalError): | ||
| self._cx.execute("PRAGMA journal_mode = wal") | ||
| if not self._readonly: |
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self._readonly is not used anywhere else, is it? You could just use flag != "ro" directly:
| if not self._readonly: | |
| if flag != "ro": |
What
This PR adds the SQLite URI parameter
immutable=1when opening a database in read-only mode inLib/dbm/sqlite3.py. This explicitly informs SQLite that the database is read-only and avoids attempts to create or write to auxiliary WAL/SHM files.Why
Without this flag, opening a read-only SQLite database may fail with errors such as "unable to open database file" when the WAL or SHM files cannot be created due to filesystem permissions or other restrictions. This is especially common when the database file is read-only and the environment prevents creation of additional files.
Adding
immutable=1allows SQLite to operate correctly without needing to create WAL/SHM files, thus preventing these errors.Where
The change is made in the
_Database.__init__constructor inLib/dbm/sqlite3.py. The URI used to open the database connection is appended with&immutable=1only if theflagis"ro"(read-only).Related issue
#135386
This is my first contribution to CPython. I appreciate the opportunity and look forward to feedback from the community. Thank you!