dendrite/roomserver
kegsay c849e74dfc
db migration: fix #1844 and add additional assertions (#1889)
* db migration: fix #1844 and add additional assertions

- Migration scripts will now check to see if there are any unconverted
  snapshot IDs and fail the migration if there are any. This should
  prevent people from getting a corrupt database in the event the root
  cause is still unknown.
- Add an ORDER BY clause when doing batch queries in the postgres
  migration. LIMIT and OFFSET without ORDER BY are undefined and must
  not be relied upon to produce a deterministic ordering (e.g row order).
  See https://www.postgresql.org/docs/current/queries-limit.html

* Linting

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
2021-06-29 11:25:17 +01:00
..
acls Pass pointers to events — reloaded (#1583) 2020-11-16 15:44:53 +00:00
api Fix appsevice alias queries part 2 (#1684) 2021-03-03 17:00:31 +00:00
auth Pass pointers to events — reloaded (#1583) 2020-11-16 15:44:53 +00:00
internal Use a custom FIFO queue for the RS input API (#1888) 2021-06-28 15:11:36 +01:00
inthttp Peeking over federation via MSC2444 (#1391) 2021-01-22 14:55:08 +00:00
state Increase gocyclo complexity to 25 (and remove all but 2 golint directives related to it) (#1783) 2021-03-03 14:35:57 +00:00
storage db migration: fix #1844 and add additional assertions (#1889) 2021-06-29 11:25:17 +01:00
types State storage refactor (#1839) 2021-04-26 13:25:57 +01:00
version Set default room version to v6 (#1438) 2020-09-25 12:59:57 +01:00
README.md use go module for dependencies (#594) 2019-05-21 21:56:55 +01:00
roomserver.go Top-level setup package (#1605) 2020-12-02 17:41:00 +00:00
roomserver_test.go Top-level setup package (#1605) 2020-12-02 17:41:00 +00:00

README.md

RoomServer

RoomServer Internals

Numeric IDs

To save space matrix string identifiers are mapped to local numeric IDs. The numeric IDs are more efficient to manipulate and use less space to store. The numeric IDs are never exposed in the API the room server exposes. The numeric IDs are converted to string IDs before they leave the room server. The numeric ID for a string ID is never 0 to avoid being confused with go's default zero value. Zero is used to indicate that there was no corresponding string ID. Well-known event types and event state keys are preassigned numeric IDs.

State Snapshot Storage

The room server stores the state of the matrix room at each event. For efficiency the state is stored as blocks of 3-tuples of numeric IDs for the event type, event state key and event ID. For further efficiency the state snapshots are stored as the combination of up to 64 these blocks. This allows blocks of the room state to be reused in multiple snapshots.

The resulting database tables look something like this:

+-------------------------------------------------------------------+
| Events                                                            |
+---------+-------------------+------------------+------------------+
| EventNID| EventTypeNID      | EventStateKeyNID | StateSnapshotNID |
+---------+-------------------+------------------+------------------+
|       1 | m.room.create   1 | ""             1 | <nil>          0 |
|       2 | m.room.member   2 | "@user:foo"    2 | <nil>          0 |
|       3 | m.room.member   2 | "@user:bar"    3 | {1,2}          1 |
|       4 | m.room.message  3 | <nil>          0 | {1,2,3}        2 |
|       5 | m.room.member   2 | "@user:foo"    2 | {1,2,3}        2 |
|       6 | m.room.message  3 | <nil>          0 | {1,3,6}        3 |
+---------+-------------------+------------------+------------------+

+----------------------------------------+
| State Snapshots                        |
+-----------------------+----------------+
| EventStateSnapshotNID | StateBlockNIDs |
+-----------------------+----------------|
|                     1 |           {1}  |
|                     2 |         {1,2}  |
|                     3 |       {1,2,3}  |
+-----------------------+----------------+

+-----------------------------------------------------------------+
| State Blocks                                                    |
+---------------+-------------------+------------------+----------+
| StateBlockNID | EventTypeNID      | EventStateKeyNID | EventNID |
+---------------+-------------------+------------------+----------+
|             1 | m.room.create   1 | ""             1 |        1 |
|             1 | m.room.member   2 | "@user:foo"    2 |        2 |
|             2 | m.room.member   2 | "@user:bar"    3 |        3 |
|             3 | m.room.member   2 | "@user:foo"    2 |        6 |
+---------------+-------------------+------------------+----------+