From b01f54ade1af9627aa09628851950cd45a70b9a4 Mon Sep 17 00:00:00 2001
From: tai <tai_chong@foxmail.com>
Date: Tue, 23 Jul 2019 14:18:44 +0800
Subject: [PATCH] ISSUE-5695: support push down predicate to final subquery

---
 dbms/src/Core/Settings.h                      |  3 +-
 .../PredicateExpressionsOptimizer.cpp         |  5 +-
 .../PredicateExpressionsOptimizer.h           |  4 ++
 .../00974_final_predicate_push_down.reference | 50 +++++++++++++++++++
 .../00974_final_predicate_push_down.sql       | 17 +++++++
 5 files changed, 77 insertions(+), 2 deletions(-)
 create mode 100644 dbms/tests/queries/0_stateless/00974_final_predicate_push_down.reference
 create mode 100644 dbms/tests/queries/0_stateless/00974_final_predicate_push_down.sql

diff --git a/dbms/src/Core/Settings.h b/dbms/src/Core/Settings.h
index 4df07df60f6..e55e58e9d28 100644
--- a/dbms/src/Core/Settings.h
+++ b/dbms/src/Core/Settings.h
@@ -336,7 +336,8 @@ struct Settings : public SettingsCollection<Settings>
     \
     /** Obsolete settings that do nothing but left for compatibility reasons. Remove each one after half a year of obsolescence. */ \
     \
-    M(SettingBool, allow_experimental_low_cardinality_type, true, "Obsolete setting, does nothing. Will be removed after 2019-08-13")
+    M(SettingBool, allow_experimental_low_cardinality_type, true, "Obsolete setting, does nothing. Will be removed after 2019-08-13") \
+    M(SettingBool, allow_push_predicate_to_final_subquery, 1, "Allow push predicate to final subquery.")
 
     DECLARE_SETTINGS_COLLECTION(LIST_OF_SETTINGS)
 
diff --git a/dbms/src/Interpreters/PredicateExpressionsOptimizer.cpp b/dbms/src/Interpreters/PredicateExpressionsOptimizer.cpp
index b6e6545e475..5e0d11212dc 100644
--- a/dbms/src/Interpreters/PredicateExpressionsOptimizer.cpp
+++ b/dbms/src/Interpreters/PredicateExpressionsOptimizer.cpp
@@ -138,7 +138,10 @@ bool PredicateExpressionsOptimizer::allowPushDown(
     const std::vector<IdentifierWithQualifier> & dependencies,
     OptimizeKind & optimize_kind)
 {
-    if (!subquery || subquery->final() || subquery->limitBy() || subquery->limitLength() || subquery->with())
+    if (!subquery ||
+        (!settings.allow_push_predicate_to_final_subquery && subquery->final()) ||
+        subquery->limitBy() || subquery->limitLength() ||
+        subquery->with())
         return false;
     else
     {
diff --git a/dbms/src/Interpreters/PredicateExpressionsOptimizer.h b/dbms/src/Interpreters/PredicateExpressionsOptimizer.h
index b7e3cd430fc..89d2bfcfbf0 100644
--- a/dbms/src/Interpreters/PredicateExpressionsOptimizer.h
+++ b/dbms/src/Interpreters/PredicateExpressionsOptimizer.h
@@ -37,6 +37,9 @@ class PredicateExpressionsOptimizer
         const UInt64 max_expanded_ast_elements;
         const String count_distinct_implementation;
 
+        /// for final PredicatePushOptimizer
+        const bool allow_push_predicate_to_final_subquery;
+
         /// for PredicateExpressionsOptimizer
         const bool enable_optimize_predicate_expression;
         const bool join_use_nulls;
@@ -46,6 +49,7 @@ class PredicateExpressionsOptimizer
         :   max_ast_depth(settings.max_ast_depth),
             max_expanded_ast_elements(settings.max_expanded_ast_elements),
             count_distinct_implementation(settings.count_distinct_implementation),
+            allow_push_predicate_to_final_subquery(settings.allow_push_predicate_to_final_subquery),
             enable_optimize_predicate_expression(settings.enable_optimize_predicate_expression),
             join_use_nulls(settings.join_use_nulls)
         {}
diff --git a/dbms/tests/queries/0_stateless/00974_final_predicate_push_down.reference b/dbms/tests/queries/0_stateless/00974_final_predicate_push_down.reference
new file mode 100644
index 00000000000..55b5763f76b
--- /dev/null
+++ b/dbms/tests/queries/0_stateless/00974_final_predicate_push_down.reference
@@ -0,0 +1,50 @@
+{
+	"meta":
+	[
+		{
+			"name": "COUNT()",
+			"type": "UInt64"
+		}
+	],
+
+	"data":
+	[
+		{
+			"COUNT()": "1"
+		}
+	],
+
+	"rows": 1,
+
+	"statistics":
+	{
+		"elapsed": 0.000780393,
+		"rows_read": 4,
+		"bytes_read": 16
+	}
+}
+{
+	"meta":
+	[
+		{
+			"name": "COUNT()",
+			"type": "UInt64"
+		}
+	],
+
+	"data":
+	[
+		{
+			"COUNT()": "1"
+		}
+	],
+
+	"rows": 1,
+
+	"statistics":
+	{
+		"elapsed": 0.000687364,
+		"rows_read": 2,
+		"bytes_read": 8
+	}
+}
diff --git a/dbms/tests/queries/0_stateless/00974_final_predicate_push_down.sql b/dbms/tests/queries/0_stateless/00974_final_predicate_push_down.sql
new file mode 100644
index 00000000000..76b39b09acb
--- /dev/null
+++ b/dbms/tests/queries/0_stateless/00974_final_predicate_push_down.sql
@@ -0,0 +1,17 @@
+DROP TABLE IF EXISTS test_00974;
+
+CREATE TABLE test_00974
+(
+    date Date,
+    x Int32,
+    ver UInt64
+)
+ENGINE = ReplacingMergeTree(date, x, 4096);
+
+INSERT INTO test_00974 VALUES ('2019-07-23', 1, 1), ('2019-07-23', 1, 2);
+INSERT INTO test_00974 VALUES ('2019-07-23', 2, 1), ('2019-07-23', 2, 2);
+
+SELECT COUNT() FROM (SELECT * FROM test_00974 FINAL) where x = 1 SETTINGS allow_push_predicate_to_final_subquery = 0  FORMAT JSON ;
+SELECT COUNT() FROM (SELECT * FROM test_00974 FINAL) where x = 1 SETTINGS allow_push_predicate_to_final_subquery = 1  FORMAT JSON ;
+
+DROP TABLE test_00974;