Merge pull request #525 from matrix-org/erikj/select_many

Implement a `_simple_select_many_batch`

1 files changed, 72 insertions, 0 deletions

diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 183a752387..90d7aee94a 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -629,6 +629,78 @@ class SQLBaseStore(object):
 
         return self.cursor_to_dict(txn)
 
+    @defer.inlineCallbacks
+    def _simple_select_many_batch(self, table, column, iterable, retcols,
+                                  keyvalues={}, desc="_simple_select_many_batch",
+                                  batch_size=100):
+        """Executes a SELECT query on the named table, which may return zero or
+        more rows, returning the result as a list of dicts.
+
+        Filters rows by if value of `column` is in `iterable`.
+
+        Args:
+            table : string giving the table name
+            column : column name to test for inclusion against `iterable`
+            iterable : list
+            keyvalues : dict of column names and values to select the rows with
+            retcols : list of strings giving the names of the columns to return
+        """
+        results = []
+
+        if not iterable:
+            defer.returnValue(results)
+
+        chunks = [iterable[i:i+batch_size] for i in xrange(0, len(iterable), batch_size)]
+        for chunk in chunks:
+            rows = yield self.runInteraction(
+                desc,
+                self._simple_select_many_txn,
+                table, column, chunk, keyvalues, retcols
+            )
+
+            results.extend(rows)
+
+        defer.returnValue(results)
+
+    def _simple_select_many_txn(self, txn, table, column, iterable, keyvalues, retcols):
+        """Executes a SELECT query on the named table, which may return zero or
+        more rows, returning the result as a list of dicts.
+
+        Filters rows by if value of `column` is in `iterable`.
+
+        Args:
+            txn : Transaction object
+            table : string giving the table name
+            column : column name to test for inclusion against `iterable`
+            iterable : list
+            keyvalues : dict of column names and values to select the rows with
+            retcols : list of strings giving the names of the columns to return
+        """
+        if not iterable:
+            return []
+
+        sql = "SELECT %s FROM %s" % (", ".join(retcols), table)
+
+        clauses = []
+        values = []
+        clauses.append(
+            "%s IN (%s)" % (column, ",".join("?" for _ in iterable))
+        )
+        values.extend(iterable)
+
+        for key, value in keyvalues.items():
+            clauses.append("%s = ?" % (key,))
+            values.append(value)
+
+        if clauses:
+            sql = "%s WHERE %s" % (
+                sql,
+                " AND ".join(clauses),
+            )
+
+        txn.execute(sql, values)
+        return self.cursor_to_dict(txn)
+
     def _simple_update_one(self, table, keyvalues, updatevalues,
                            desc="_simple_update_one"):
         """Executes an UPDATE query on the named table, setting new values for