diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index abc7d8a5d2..792f2e7cdf 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -1117,7 +1117,7 @@ class DatabasePool:
txn: LoggingTransaction,
table: str,
keys: Collection[str],
- values: Iterable[Iterable[Any]],
+ values: Collection[Iterable[Any]],
) -> None:
"""Executes an INSERT query on the named table.
@@ -1130,6 +1130,9 @@ class DatabasePool:
keys: list of column names
values: for each row, a list of values in the same order as `keys`
"""
+ # If there's nothing to insert, then skip executing the query.
+ if not values:
+ return
if isinstance(txn.database_engine, PostgresEngine):
# We use `execute_values` as it can be a lot faster than `execute_batch`,
@@ -1455,7 +1458,7 @@ class DatabasePool:
key_names: Collection[str],
key_values: Collection[Iterable[Any]],
value_names: Collection[str],
- value_values: Iterable[Iterable[Any]],
+ value_values: Collection[Iterable[Any]],
) -> None:
"""
Upsert, many times.
@@ -1468,6 +1471,19 @@ class DatabasePool:
value_values: A list of each row's value column values.
Ignored if value_names is empty.
"""
+ # If there's nothing to upsert, then skip executing the query.
+ if not key_values:
+ return
+
+ # No value columns, therefore make a blank list so that the following
+ # zip() works correctly.
+ if not value_names:
+ value_values = [() for x in range(len(key_values))]
+ elif len(value_values) != len(key_values):
+ raise ValueError(
+ f"{len(key_values)} key rows and {len(value_values)} value rows: should be the same number."
+ )
+
if table not in self._unsafe_to_upsert_tables:
return self.simple_upsert_many_txn_native_upsert(
txn, table, key_names, key_values, value_names, value_values
@@ -1502,10 +1518,6 @@ class DatabasePool:
value_values: A list of each row's value column values.
Ignored if value_names is empty.
"""
- # No value columns, therefore make a blank list so that the following
- # zip() works correctly.
- if not value_names:
- value_values = [() for x in range(len(key_values))]
# Lock the table just once, to prevent it being done once per row.
# Note that, according to Postgres' documentation, once obtained,
@@ -1543,10 +1555,7 @@ class DatabasePool:
allnames.extend(value_names)
if not value_names:
- # No value columns, therefore make a blank list so that the
- # following zip() works correctly.
latter = "NOTHING"
- value_values = [() for x in range(len(key_values))]
else:
latter = "UPDATE SET " + ", ".join(
k + "=EXCLUDED." + k for k in value_names
@@ -1910,6 +1919,7 @@ class DatabasePool:
Returns:
The results as a list of tuples.
"""
+ # If there's nothing to select, then skip executing the query.
if not iterable:
return []
@@ -2044,6 +2054,9 @@ class DatabasePool:
raise ValueError(
f"{len(key_values)} key rows and {len(value_values)} value rows: should be the same number."
)
+ # If there is nothing to update, then skip executing the query.
+ if not key_values:
+ return
# List of tuples of (value values, then key values)
# (This matches the order needed for the query)
@@ -2278,6 +2291,7 @@ class DatabasePool:
Returns:
Number rows deleted
"""
+ # If there's nothing to delete, then skip executing the query.
if not values:
return 0
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