diff options
Diffstat (limited to 'synapse/storage/database.py')
| -rw-r--r-- | synapse/storage/database.py | 62 |
1 files changed, 7 insertions, 55 deletions
diff --git a/synapse/storage/database.py b/synapse/storage/database.py index 94590e7b45..a2f016a7ef 100644 --- a/synapse/storage/database.py +++ b/synapse/storage/database.py @@ -2060,68 +2060,20 @@ KV = TypeVar("KV") def make_tuple_comparison_clause( - database_engine: BaseDatabaseEngine, keys: List[Tuple[str, KV]] + _database_engine: BaseDatabaseEngine, keys: List[Tuple[str, KV]] ) -> Tuple[str, List[KV]]: """Returns a tuple comparison SQL clause - Depending what the SQL engine supports, builds a SQL clause that looks like either - "(a, b) > (?, ?)", or "(a > ?) OR (a == ? AND b > ?)". + Builds a SQL clause that looks like "(a, b) > (?, ?)" Args: - database_engine + _database_engine keys: A set of (column, value) pairs to be compared. Returns: A tuple of SQL query and the args """ - if database_engine.supports_tuple_comparison: - return ( - "(%s) > (%s)" % (",".join(k[0] for k in keys), ",".join("?" for _ in keys)), - [k[1] for k in keys], - ) - - # we want to build a clause - # (a > ?) OR - # (a == ? AND b > ?) OR - # (a == ? AND b == ? AND c > ?) - # ... - # (a == ? AND b == ? AND ... AND z > ?) - # - # or, equivalently: - # - # (a > ? OR (a == ? AND - # (b > ? OR (b == ? AND - # ... - # (y > ? OR (y == ? AND - # z > ? - # )) - # ... - # )) - # )) - # - # which itself is equivalent to (and apparently easier for the query optimiser): - # - # (a >= ? AND (a > ? OR - # (b >= ? AND (b > ? OR - # ... - # (y >= ? AND (y > ? OR - # z > ? - # )) - # ... - # )) - # )) - # - # - - clause = "" - args = [] # type: List[KV] - for k, v in keys[:-1]: - clause = clause + "(%s >= ? AND (%s > ? OR " % (k, k) - args.extend([v, v]) - - (k, v) = keys[-1] - clause += "%s > ?" % (k,) - args.append(v) - - clause += "))" * (len(keys) - 1) - return clause, args + return ( + "(%s) > (%s)" % (",".join(k[0] for k in keys), ",".join("?" for _ in keys)), + [k[1] for k in keys], + ) |