Basically, I eliminate the use of select_all() in a query
that still makes a single round trip. We have good test
enforcement that Django never needs to lazily fetch
objects off the Stream object. (It used to be common
to fetch stream.realm a while back, but we upgraded
bulk_add_subscription, in particular, a while back.)
At least as measured by test_events.py, which has over 1000
calls to fetch initial data for page loads, this should
be about a 10% improvement in how much time the server
spends fetching data.
We mostly avoid a select_related() query that did this nastiness:
INNER JOIN "zerver_realm" ON ("zerver_stream"."realm_id" = "zerver_realm"."id")
INNER JOIN "zerver_usergroup" ON ("zerver_stream"."can_remove_subscribers_group_id" = "zerver_usergroup"."id")
INNER JOIN "zerver_realm" T4 ON ("zerver_usergroup"."realm_id" = T4."id")
INNER JOIN "zerver_usergroup" T5 ON ("zerver_usergroup"."can_mention_group_id" = T5."id")
INNER JOIN "zerver_realm" T6 ON (T5."realm_id" = T6."id")
INNER JOIN "zerver_usergroup" T7 ON (T5."can_mention_group_id" = T7."id")
INNER JOIN "zerver_realm" T8 ON (T7."realm_id" = T8."id")
INNER JOIN "zerver_usergroup" T9 ON (T7."can_mention_group_id" = T9."id")
INNER JOIN "zerver_realm" T10 ON (T9."realm_id" = T10."id")
INNER JOIN "zerver_usergroup" T11 ON (T9."can_mention_group_id" = T11."id")
WHERE "zerver_stream"."id" IN (SELECT U0."stream_id" FROM "zerver_defaultstream" U0 WHERE U0."realm_id" = 2
Future commits will address the codepath for creating users.
I created zerver/lib/default_streams.py, so that various
views and events.py don't have to awkwardly reach into
an "actions" file.
I copied over two functions verbatim from actions/default_streams.py:
get_default_streams_for_realm
streams_to_dicts_sorted
The latter only remains as an internal detail in the new library.
I also created two new helpers:
get_default_stream_ids_for_realm:
This is both faster and easier to use in all the places
where we only need to get a set of default stream ids.
get_default_streams_for_realm_as_dicts:
This just wraps the prior calls to
streams_to_dicts_sorted(get_default_streams_for_realm(...)),
and it doesn't yet address the slowness of the underlying
code.
All the "real" code should be functionally the same.
In a few tests I now use this wrapper instead of
calling get_default_streams_for_realm, just to get
slightly deeper coverage.
Steve Howell