3 ms·

sqlite_rsync can only be used in WAL mode. A further constraint of WAL mode is the database file must be stored on local disk. Clearly, you'd want to do this

sqlite_rsync can only be used in WAL mode. A further constraint of WAL mode is the database file must be stored on local disk. Clearly, you'd want to do this almost all the time, but for the times this is not possible this utility won't work.

SQLite 2y ago
I just checked in an experimental change to sqlite3_rsync that allows it to work on non-WAL-mode database files, as long as you do not use the --wal-only command-line option. The downside of this is that the origin database will block all writers while the sync is going on, and the replicate database will block both reads and writers during the sync, because to do otherwise requires WAL-mode. Nevertheless, being able to sync DELETE-mode databases might well be useful, as you observe. If you are able, please try out this enhancement and let me know if it solves your problem. See <https://sqlite.org/src/info/2025-05-01T16:07Z https://sqlite.org/src/info/2025-05-01T16:07Z> for the patch.
- SQLite 2y ago
  Update: This enhancement is now on trunk and will be included in the 3.50.0 release of SQLite due out in about four weeks.
remram 2y ago
WAL mode works on many network filesystems provided it's being written from a single host at a time.
- jgalt212 2y ago
  I'm not sure understand your comment. Regardless of WAL or network filesystem usage, the sqlite file cannot be written to from multiple processes simultaneously. Am I missing something here, or did you misstate?
  - remram 2y ago
    You can have multiple writer connections from multiple writer processes (on one host at a time). Their transactions will be safely serialized by SQLite. So, sure, from a low-level point of view, the write transactions are not really simultaneous (they never are with SQLite3), but from the user perspective they are in the sense that you don't need to serialize them yourself.

SQLite 2y ago

I just checked in an experimental change to sqlite3_rsync that allows it to work on non-WAL-mode database files, as long as you do not use the --wal-only command-line option. The downside of this is that the origin database will block all writers while the sync is going on, and the replicate database will block both reads and writers during the sync, because to do otherwise requires WAL-mode. Nevertheless, being able to sync DELETE-mode databases might well be useful, as you observe. If you are able, please try out this enhancement and let me know if it solves your problem. See <https://sqlite.org/src/info/2025-05-01T16:07Z https://sqlite.org/src/info/2025-05-01T16:07Z> for the patch.

SQLite 2y ago
Update: This enhancement is now on trunk and will be included in the 3.50.0 release of SQLite due out in about four weeks.

remram 2y ago

WAL mode works on many network filesystems provided it's being written from a single host at a time.

jgalt212 2y ago
I'm not sure understand your comment. Regardless of WAL or network filesystem usage, the sqlite file cannot be written to from multiple processes simultaneously. Am I missing something here, or did you misstate?
- remram 2y ago
  You can have multiple writer connections from multiple writer processes (on one host at a time). Their transactions will be safely serialized by SQLite. So, sure, from a low-level point of view, the write transactions are not really simultaneous (they never are with SQLite3), but from the user perspective they are in the sense that you don't need to serialize them yourself.