[GitHub] [airflow] mik-laj commented on a change in pull request #6792: [AIRFLOW-5930] Use cached-SQL query building for hot-path queries

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mik-laj commented on a change in pull request #6792: [AIRFLOW-5930] Use cached-SQL query building for hot-path queries
URL: https://github.com/apache/airflow/pull/6792#discussion_r356986173
 
 

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 File path: airflow/ti_deps/deps/trigger_rule_dep.py
 ##########
 @@ -34,9 +35,38 @@ class TriggerRuleDep(BaseTIDep):
     IGNOREABLE = True
     IS_TASK_DEP = True
 
+    @staticmethod
+    def bake_dep_status_query():
+        TI = airflow.models.TaskInstance
+        # TODO(unknown): this query becomes quite expensive with dags that have many
+        # tasks. It should be refactored to let the task report to the dag run and get the
+        # aggregates from there.
+        q = BAKED_QUERIES(lambda session: session.query(
+            func.coalesce(func.sum(case([(TI.state == State.SUCCESS, 1)], else_=0)), 0),
 
 Review comment:
   Can you provide me this query in SQL format? I think it can be optimized for PostgresQL by using COUNT...FILTER syntax. However, this also requires checking if this syntax has an effect on performance, or is it just syntactic sugar.
   https://www.postgresql.org/docs/9.4/sql-expressions.html#SYNTAX-AGGREGATES

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