SQLar[1], see [2] for some reasoning around why a database is preferred over zipped XML. Though, I'd be fine with a DBM-style database too as we only need the key-value part of it.

[1] https://sqlite.org/sqlar/doc/trunk/README.md

[2] https://www.sqlite.org/affcase1.html

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chungy an hour ago | parent | next [-]

the SQLite archive format (it's probably worth linking to the main documentation[1], instead of the very old experimental repository) may not really be a good fit for something like GIMP's native file format. (To be clear, "SQLite archives" are not special compared to any other database: it's just a well-defined schema for an sqlar table, which the sqlite3 command line tool is able to create, update, and extract using syntax like the tar command.)

That being said, SQLite would still be a good choice, especially as it's a format that's really intended to be modified in-place, and has good data integrity features (eg: keep WAL enabled so that mid-save crashes/shutdowns don't corrupt your file), neither of which are provided by Zip. You could even just run zlib on data (be it XML or what have you) if optimizing the on-disk size of the file is desirable.

[1] https://sqlite.org/cli.html#sqlite_archive_support

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flohofwoe an hour ago | parent | prev [-]

The problem with using database blobs for load/save is that you usually need a full database client in the application. SQlite advertises that use case, but it is complete overkill. You never need to run any sort of complex SQL query on an image file format for instance. Using XML+ZIP in this day and age is also a strange decision, but at least that way the data is inspectable with unzip, a text editor and an image viewer (assuming they use a standard image format to store the raw pixel data).

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TeMPOraL 44 minutes ago | parent [-]

> You never need to run any sort of complex SQL query on an image file format for instance.

Sure you will. Plenty of features that don't exist, or are implemented badly, because you can't easily do it.

Quick mental translation table: if you think "iterate over every ..." or a `for` loop, that's your SELECT query. If you think about `if` conditions, that's the parts that go after FROM clause.

	▲	x3ro 36 minutes ago \| parent \| next [-]
		In order to have any advantage from this, you would have the added complexity of splitting your file format into tables that can be queried in a useful manner. However, for an image file format, you most likely need to hold the entire definition in memory at all times anyway. Assuming that’s the case, doesn’t XPath get you there most of the way (assuming XML), with _way_ less complexity?
	▲	zelphirkalt 7 minutes ago \| parent \| prev [-]
		SQLite is fast, but it won't be faster than a hot loop in C. Having the loop construct dictated by the file format seems bad. For images it seems more reasonable to have them in-memory, except for huge image edge cases.