Its not a big deal that this isnt possible. I completely understand the problems caused by arbitrary renaming, but was hoping sqlite's existing locking mechanisms could be used to allow a safe rename in a controlled manner. Thats pretty clear, but I was hoping it was an oversimplification. Renaming an open database file results in behavior that is undefined Ive got a good understanding of the relative advantages of all these options. For example, archiving a dataset and starting afresh could be achieved by renaming the dataset database file. These options allow some application requirements to be satisfied in a (potentially) simpler manner, outside the database. Maybe it stores related instruments in separate databases. Maybe it could store all the measurements from each instrument in separate databases. This would be the one obvious design if using a server-based database.īut sqlite's one-file-per-database model offers a spectrum of other design options. I can see a design which puts everything in one database. Queries normally involve a large number of measurements from a single instrument, and rarely involve more than one instrument. There are several writer processes, recording new timestamped measurements from measurement instruments. I am at the design stage for an application which involves collecting measurements from various measurement instruments. If you have data it should be in a database, not the name of a file on a storage device. A file's name is not data, it's an obscure detail of how computers maintain some kinds of storage. Once again: anything that has meaning is data. And they're further complicated because SQLite automatically makes and deletes files with similar names to the database as it works and does not get notified if a filename is changed while its in use. because it ran out of file handles) then crash when it tries to reopen the file.Īllow renaming, after closing all file handles for the file, meaning that the application which had the file open will crash the next time it tries to use it.Īll of these present problems for anything that relies on you renaming files. This means that the application may temporarily close the file (e.g. Various combinations of theseīlock attempts to rename a file which is open.Īllow renaming an open file but do not notify the applications which have it open. The behaviour depends on both the operating system and the file system. That has the database file renamed out from under it tries to write, thatĬould result in database corruption in the worst case. It might cause problems for that other application. SQLite database out from under another application that is actively using Have the database open, you can rename it all you want. SQLite in that way, you can rename the database file whenever you like,īut, if you make use of incremental I/O, transactions, or guarantees ofĬonsistency across power failures, then the rule is that you may not rename Or the backup api or the VACUUM INTO command. For writing theĭatabase back to disk, you can use the sqlite3_serialize() interface Useful for loading an entire database into memory. The sqlite3_deserialize() interface might be SQLite by reading the entire database into memory, working with theĭatabase while in-memory, then writing the entire thing back out to disk Write the whole thing out to disk (non-atomically) in one go when you do They instead keep the entire file in memory, and the Multiple applications to read/write the same file at the same time, nor are Their file content if a power-loss occurs while writing, nor do they allow Spreadsheets do not incrementally write their files, nor do they preserve That somewhat contradicts the suggestion that sqlite works well as an application file format.
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