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],
+ )
|
