Don't limit "state" (#2849)

This is apparently some incorrect behaviour that we built as a result of
a spec bug (matrix-org/matrix-spec#1314) where we were applying a filter
to the `"state"` section of the `/sync` response incorrectly. The client
then has no way to know that the state was limited.

This PR removes the state limiting, which probably also helps #2842.

syncapi/storage/postgres/current_room_state_table.go

@@ -91,8 +91,7 @@ const selectCurrentStateSQL = "" +
 	" AND ( $4::text[] IS NULL OR     type LIKE ANY($4)  )" +
 	" AND ( $5::text[] IS NULL OR NOT(type LIKE ANY($5)) )" +
 	" AND ( $6::bool IS NULL   OR     contains_url = $6  )" +
-	" AND (event_id = ANY($7)) IS NOT TRUE" +
-	" LIMIT $8"
+	" AND (event_id = ANY($7)) IS NOT TRUE"
 
 const selectJoinedUsersSQL = "" +
 	"SELECT room_id, state_key FROM syncapi_current_room_state WHERE type = 'm.room.member' AND membership = 'join'"
@@ -290,7 +289,6 @@ func (s *currentRoomStateStatements) SelectCurrentState(
 		pq.StringArray(filterConvertTypeWildcardToSQL(stateFilter.NotTypes)),
 		stateFilter.ContainsURL,
 		pq.StringArray(excludeEventIDs),
-		stateFilter.Limit,
 	)
 	if err != nil {
 		return nil, err

syncapi/storage/postgres/output_room_events_table.go

@@ -144,8 +144,7 @@ const selectStateInRangeFilteredSQL = "" +
 	" AND ( $6::text[] IS NULL OR     type LIKE ANY($6)  )" +
 	" AND ( $7::text[] IS NULL OR NOT(type LIKE ANY($7)) )" +
 	" AND ( $8::bool IS NULL   OR     contains_url = $8  )" +
-	" ORDER BY id ASC" +
-	" LIMIT $9"
+	" ORDER BY id ASC"
 
 // In order for us to apply the state updates correctly, rows need to be ordered in the order they were received (id).
 const selectStateInRangeSQL = "" +
@@ -153,8 +152,7 @@ const selectStateInRangeSQL = "" +
 	" FROM syncapi_output_room_events" +
 	" WHERE (id > $1 AND id <= $2) AND (add_state_ids IS NOT NULL OR remove_state_ids IS NOT NULL)" +
 	" AND room_id = ANY($3)" +
-	" ORDER BY id ASC" +
-	" LIMIT $4"
+	" ORDER BY id ASC"
 
 const deleteEventsForRoomSQL = "" +
 	"DELETE FROM syncapi_output_room_events WHERE room_id = $1"
@@ -264,13 +262,11 @@ func (s *outputRoomEventsStatements) SelectStateInRange(
 			pq.StringArray(filterConvertTypeWildcardToSQL(stateFilter.Types)),
 			pq.StringArray(filterConvertTypeWildcardToSQL(stateFilter.NotTypes)),
 			stateFilter.ContainsURL,
-			stateFilter.Limit,
 		)
 	} else {
 		stmt := sqlutil.TxStmt(txn, s.selectStateInRangeStmt)
 		rows, err = stmt.QueryContext(
 			ctx, r.Low(), r.High(), pq.StringArray(roomIDs),
-			r.High()-r.Low(),
 		)
 	}
 

syncapi/storage/sqlite3/current_room_state_table.go

@@ -277,7 +277,8 @@ func (s *currentRoomStateStatements) SelectCurrentState(
 		},
 		stateFilter.Senders, stateFilter.NotSenders,
 		stateFilter.Types, stateFilter.NotTypes,
-		excludeEventIDs, stateFilter.ContainsURL, stateFilter.Limit, FilterOrderNone,
+		excludeEventIDs, stateFilter.ContainsURL, 0,
+		FilterOrderNone,
 	)
 	if err != nil {
 		return nil, fmt.Errorf("s.prepareWithFilters: %w", err)

syncapi/storage/sqlite3/filtering.go

@@ -84,8 +84,10 @@ func prepareWithFilters(
 	case FilterOrderDesc:
 		query += " ORDER BY id DESC"
 	}
-	query += fmt.Sprintf(" LIMIT $%d", offset+1)
-	params = append(params, limit)
+	if limit > 0 {
+		query += fmt.Sprintf(" LIMIT $%d", offset+1)
+		params = append(params, limit)
+	}
 
 	var stmt *sql.Stmt
 	var err error

syncapi/storage/sqlite3/output_room_events_table.go

@@ -200,7 +200,7 @@ func (s *outputRoomEventsStatements) SelectStateInRange(
 			s.db, txn, stmtSQL, inputParams,
 			stateFilter.Senders, stateFilter.NotSenders,
 			stateFilter.Types, stateFilter.NotTypes,
-			nil, stateFilter.ContainsURL, stateFilter.Limit, FilterOrderAsc,
+			nil, stateFilter.ContainsURL, 0, FilterOrderAsc,
 		)
 	} else {
 		stmt, params, err = prepareWithFilters(