Fix early constant folding for isNull/isNotNul and analyzer.

src/DataTypes/DataTypeNullable.cpp

@@ -3,6 +3,7 @@
 #include <DataTypes/DataTypeFactory.h>
 #include <DataTypes/Serializations/SerializationNullable.h>
 #include <DataTypes/DataTypeLowCardinality.h>
+#include <DataTypes/DataTypeVariant.h>
 #include <Columns/ColumnNullable.h>
 #include <Columns/ColumnConst.h>
 #include <Core/Field.h>
@@ -174,4 +175,17 @@ DataTypePtr removeNullableOrLowCardinalityNullable(const DataTypePtr & type)
 
 }
 
+bool canContainNull(const IDataType & type)
+    {
+        if (type.isNullable() || type.isLowCardinalityNullable() || isDynamic(type))
+            return true;
+
+        if (const auto * variant = typeid_cast<const DataTypeVariant *>(&type))
+            for (const auto & elem : variant->getVariants())
+                if (canContainNull(*elem))
+                    return true;
+
+        return false;
+    }
+
 }

src/DataTypes/DataTypeNullable.h

@@ -62,4 +62,6 @@ DataTypePtr makeNullableOrLowCardinalityNullableSafe(const DataTypePtr & type);
 /// Nullable(T) -> T, LowCardinality(Nullable(T)) -> T
 DataTypePtr removeNullableOrLowCardinalityNullable(const DataTypePtr & type);
 
+bool canContainNull(const IDataType & type);
+
 }

src/Functions/isNotNull.cpp

@@ -29,6 +29,18 @@ public:
         return name;
     }
 
+    ColumnPtr getConstantResultForNonConstArguments(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type) const override
+    {
+        const ColumnWithTypeAndName & elem = arguments[0];
+        if (elem.type->onlyNull())
+            return result_type->createColumnConst(1, UInt8(0));
+
+        if (canContainNull(*elem.type))
+            return nullptr;
+
+        return result_type->createColumnConst(1, UInt8(1));
+    }
+
     size_t getNumberOfArguments() const override { return 1; }
     bool useDefaultImplementationForNulls() const override { return false; }
     bool useDefaultImplementationForConstants() const override { return true; }

src/Functions/isNull.cpp

@@ -31,6 +31,18 @@ public:
         return name;
     }
 
+    ColumnPtr getConstantResultForNonConstArguments(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type) const override
+    {
+        const ColumnWithTypeAndName & elem = arguments[0];
+        if (elem.type->onlyNull())
+            return result_type->createColumnConst(1, UInt8(1));
+
+        if (canContainNull(*elem.type))
+            return nullptr;
+
+        return result_type->createColumnConst(1, UInt8(0));
+    }
+
     size_t getNumberOfArguments() const override { return 1; }
     bool useDefaultImplementationForNulls() const override { return false; }
     bool useDefaultImplementationForLowCardinalityColumns() const override { return false; }

src/Functions/isNullable.cpp

@@ -2,6 +2,7 @@
 #include <Functions/FunctionFactory.h>
 #include <DataTypes/DataTypesNumber.h>
 #include <Columns/ColumnsNumber.h>
+#include <DataTypes/DataTypeNullable.h>
 
 namespace DB
 {
@@ -23,6 +24,15 @@ public:
         return name;
     }
 
+    ColumnPtr getConstantResultForNonConstArguments(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type) const override
+    {
+        const ColumnWithTypeAndName & elem = arguments[0];
+        if (elem.type->onlyNull() || canContainNull(*elem.type))
+            return result_type->createColumnConst(1, UInt8(1));
+
+        return result_type->createColumnConst(1, UInt8(0));
+    }
+
     bool useDefaultImplementationForNulls() const override { return false; }
 
     bool useDefaultImplementationForNothing() const override { return false; }

src/Planner/PlannerExpressionAnalysis.cpp

@@ -1,6 +1,7 @@
 #include <Planner/PlannerExpressionAnalysis.h>
 
 #include <Columns/ColumnNullable.h>
+#include <Columns/FilterDescription.h>
 
 #include <DataTypes/DataTypesNumber.h>
 #include <DataTypes/DataTypeNullable.h>
@@ -37,7 +38,7 @@ namespace
   * Actions before filter are added into into actions chain.
   * It is client responsibility to update filter analysis result if filter column must be removed after chain is finalized.
   */
-FilterAnalysisResult analyzeFilter(const QueryTreeNodePtr & filter_expression_node,
+std::optional<FilterAnalysisResult> analyzeFilter(const QueryTreeNodePtr & filter_expression_node,
     const ColumnsWithTypeAndName & input_columns,
     const PlannerContextPtr & planner_context,
     ActionsChain & actions_chain)
@@ -45,7 +46,11 @@ FilterAnalysisResult analyzeFilter(const QueryTreeNodePtr & filter_expression_no
     FilterAnalysisResult result;
 
     result.filter_actions = buildActionsDAGFromExpressionNode(filter_expression_node, input_columns, planner_context);
-    result.filter_column_name = result.filter_actions->getOutputs().at(0)->result_name;
+    const auto * output = result.filter_actions->getOutputs().at(0);
+    if (output->column && ConstantFilterDescription(*output->column).always_true)
+        return {};
+
+    result.filter_column_name = output->result_name;
     actions_chain.addStep(std::make_unique<ActionsChainStep>(result.filter_actions));
 
     return result;

tests/queries/0_stateless/03164_early_constant_folding_analyzer.reference

@@ -0,0 +1 @@
+ReadFromPreparedSource (Optimized trivial count)

tests/queries/0_stateless/03164_early_constant_folding_analyzer.sql

@@ -0,0 +1,30 @@
+CREATE TABLE checks
+(
+    `pull_request_number` UInt32,
+    `commit_sha` LowCardinality(String),
+    `check_name` LowCardinality(String),
+    `check_status` LowCardinality(String),
+    `check_duration_ms` UInt64,
+    `check_start_time` DateTime,
+    `test_name` LowCardinality(String),
+    `test_status` LowCardinality(String),
+    `test_duration_ms` UInt64,
+    `report_url` String,
+    `pull_request_url` String,
+    `commit_url` String,
+    `task_url` String,
+    `base_ref` String,
+    `base_repo` String,
+    `head_ref` String,
+    `head_repo` String,
+    `test_context_raw` String,
+    `instance_type` LowCardinality(String),
+    `instance_id` String,
+    `date` Date MATERIALIZED toDate(check_start_time)
+)
+ENGINE = MergeTree ORDER BY (date, pull_request_number, commit_sha, check_name, test_name, check_start_time);
+
+insert into checks select * from generateRandom() limit 1;
+
+
+select trimLeft(explain) from (explain SELECT count(1) FROM checks WHERE test_name IS NOT NULL SETTINGS allow_experimental_analyzer = 1, allow_experimental_parallel_reading_from_replicas = 0) where explain like '%ReadFromPreparedSource%';