sqlite optimizations

[cogman]

Creating new expiry key index as that's often used for lookups.

Adding "without rowid" to the table creation to reduce the size of this table on disk and improve lookup performance.

(Second PR. First one had to close as the primary key was broken with the prior PR).

[ColonelThirtyTwo]

The index does not help either of the queries as-is. Session token lookup is uniquely determined by the ID and uses its index, so the expiry index isn't used. Expiration deletion queries over datetime(expiry_date), not expiry_date directly, so it can't use the index:

sqlite> CREATE TABLE test(id TEXT PRIMARY KEY NOT NULL, expire INTEGER NOT NULL);
sqlite> CREATE INDEX test_expire ON test(expire);
sqlite> EXPLAIN QUERY PLAN SELECT * FROM test WHERE id = ? AND expire < ?;
QUERY PLAN
`--SEARCH test USING INDEX sqlite_autoindex_test_1 (id=?)
sqlite> EXPLAIN QUERY PLAN SELECT * FROM test WHERE datetime(expire) < datetime('now');
QUERY PLAN
`--SCAN test

You could create the index over datetime(expiry_date):

sqlite> CREATE INDEX test_expire2 ON test(datetime(expire));
sqlite> EXPLAIN QUERY PLAN SELECT * FROM test WHERE datetime(expire) < datetime('now');
QUERY PLAN
`--SEARCH test USING INDEX test_expire2 (<expr><?)

But in practice I'm not sure if the cost of maintaining the index on inserts/updates is worth optimizing the infrequently-ran expiry cleaner.