Merge pull request #9766 from matrix-org/rav/drop_py35

Require py36, Postgres 9.6, and sqlite 3.22

1 files changed, 6 insertions, 57 deletions

diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index 94590e7b45..b302cd5786 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -2059,69 +2059,18 @@ def make_in_list_sql_clause(
 KV = TypeVar("KV")
 
 
-def make_tuple_comparison_clause(
-    database_engine: BaseDatabaseEngine, keys: List[Tuple[str, KV]]
-) -> Tuple[str, List[KV]]:
+def make_tuple_comparison_clause(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
         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],
+    )