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Type: new Version: 3.0.7 Status: active
Created: 2004-Oct-07 20:28
Severity: 3 Last Change: 2004-Oct-07 20:28
Priority: 3 Subsystem: Unknown Assigned To: anonymous Creator: anonymous Resolution: Pending
Please add a one-step user-level test that one can invoke to determine whether a file is a valid SQLite database. I can understand open() not doing this automatically for performance reasons, but there should be an alternative for users who want behaviour as if it did. Performing a dummy select, the current recommended solution to performing the test, is a very in-elegant solution.
1. One alternative option I suggest adding a new stateless function whose prototype looks like open() but has a name like "is_a_database" or "validate_file" or what-have-you. Conceptually, what this function could do is: open(), perform smarter replacement for dummy select, close(); it would return the code for OK if the given file is a valid database, and the appropriate SQLite error code if it is not.
2. An alternative solution, which could be done instead of or in addition to the above, is a stateful function that you invoke on the structure that open() returns. A user would invoke it right after open(); they then explicitly call close() if testing the file was all they wanted to do, or otherwise they keep it open and do whatever they were going to do, but now they can be confident that any actual work will not fail due to it being an invalid file.
3. A third solution would be to add an optional boolean argument to open() which, if set true, would cause open() to perform the test in question.
I suggest that option 2 may be the best one, for multiple reasons, including both flexability, future extensibility, performance, simplicity, and non-interference with other future design plans.
I believe that making this change will result in better self-documenting code for users than the current work-around is.
I also believe that this change should be very simple to do, especially if you pick option 2.
I also request that you implement this in the 2.8.x branch as well, so that applications which can possibly work with both versions of SQLite databases have the same simplicity of testing.
Finally, something which you don't have to do, but that my recommended change would make it easier for someone else to do, is that an application could quickly scan a file system (or a single directory at least) and quickly determine which files in it are SQLite databases and which aren't, a list of valid ones it would return for a user or program to select from.
