issues

Opening db files in immutable mode sometimes leads to the file being mutated, which causes duplication in the docker image layers: see #1836, #1480

That this happens in "immutable" mode is surprising, because the sqlite docs say that setting this should open the database as read only.

https://www.sqlite.org/c3ref/open.html

immutable: The immutable parameter is a boolean query parameter that indicates that the database file is stored on read-only media. When immutable is set, SQLite assumes that the database file cannot be changed, even by a process with higher privilege, and so the database is opened read-only and all locking and change detection is disabled. Caution: Setting the immutable property on a database file that does in fact change can result in incorrect query results and/or SQLITE_CORRUPT errors. See also: SQLITE_IOCAP_IMMUTABLE.

Perhaps this is a bug in sqlite?

:books: Documentation preview :books:: https://datasette--1870.org.readthedocs.build/en/1870/

sqlite foreign keys can be compound, but that is not as well supported by datasette as single column foreign keys.

in particular,

1. in a table view, there is not a link from the row to the referenced row if the foreign key is compound
2. in a row view, there is no listing of tables and rows that refer to the focal row if those referencing foreign keys are compound.

Both of these issues are discussed in #1099.

This PR only fixes the second one, because it's not clear what the right UX is for the first issue.

Some things that might not be desirable about this approach.

1. it changes the external API, by changing column => columns and other_column => other_columns (see inline comment for more discussion.
2. There are various places where the plural foreign keys have to be checked for length and discarded or transformed to singular.

inspect_data should already include the hash and the db file size, so this PR takes advantage of using those instead of always recalculating. should help a lot on startup with large DBs.

closes #1834

Many apologies, @simonw. My previous PR #1835 did not really solve the problem because the name of the database is often not known to database object in the init method.

I took a cue from how you dealt with this issue and made hash a lazy property and did something similar with size.

:books: Documentation preview :books:: https://datasette--1837.org.readthedocs.build/en/1837/

Relates to #526

This is a minimal set of changes needed for having query CSVs attempt to download all the rows.

What's good about it is the minimalism.

What's bad about it:

1. We are abusing the _size argument to indicate we don't want truncation, which isn't the most obvious thing. Additionally, there are various checks that make sure the "_size" URL parameter is a positive integer, which we are relying on to prevent overloading.
2. The default CSV on a table page will use the max_returned_rows argument. Changing this could be a breaking change, since that's currently a place that has some facilities for pagination. Additionally, i think there's a limit under the hood somewhere which if we removed could lead to sql timeouts
3. There are similar reasons for leaving the current streaming method alone, as the current methods could allow for downloading very large files that could have a sql timeout if we tried to get them in one go.

:books: Documentation preview :books:: https://datasette--1820.org.readthedocs.build/en/1820/

This will close #1581.

I couldn't find any unit tests related to the testing hashed urls, and I know that you want to break that code out of the core application (#1561), so I'm not quite sure what you would like me to for testing.

Right now, datasette routes can only be a 2-tuple of (regex, view_fn).

If it was possible for datasette to handle extra options, like standard Django does, it would add flexibility for plugin authors.

For example, if extra options were enabled, then it would be easy to make a single table the home page (#1284). This plugin would accomplish it.

```python from datasette import hookimpl from datasette.views.table import TableView

@hookimpl def register_routes(datasette): return [ (r"^/$", TableView.as_view(datasette), {'db_name': 'DB_NAME', 'table': 'TABLE_NAME'}) ] ```