Adding support for PREWHERE in live view tables.

src/Storages/LiveView/StorageBlocks.h

@@ -26,6 +26,11 @@ public:
         return std::make_shared<StorageBlocks>(table_id, columns, std::move(pipes), to_stage);
     }
     std::string getName() const override { return "Blocks"; }
+    /// It is passed inside the query and solved at its level.
+    bool supportsPrewhere() const override { return true; }
+    bool supportsSampling() const override { return true; }
+    bool supportsFinal() const override { return true; }
+
     QueryProcessingStage::Enum getQueryProcessingStage(const Context &, QueryProcessingStage::Enum /*to_stage*/, const ASTPtr &) const override { return to_stage; }
 
     Pipes read(

src/Storages/LiveView/StorageLiveView.h

@@ -65,6 +65,7 @@ public:
     ASTPtr getInnerBlocksQuery();
 
     /// It is passed inside the query and solved at its level.
+    bool supportsPrewhere() const override { return true; }
     bool supportsSampling() const override { return true; }
     bool supportsFinal() const override { return true; }
 

tests/queries/0_stateless/00973_live_view_select_prewhere.reference

@@ -0,0 +1,4 @@
+5	1
+5	1
+10	2
+10	2

tests/queries/0_stateless/00973_live_view_select_prewhere.sql

@@ -0,0 +1,20 @@
+SET allow_experimental_live_view = 1;
+
+DROP TABLE IF EXISTS lv;
+DROP TABLE IF EXISTS mt;
+
+CREATE TABLE mt (a Int32) Engine=MergeTree order by tuple();
+CREATE LIVE VIEW lv AS SELECT sum(a) FROM mt PREWHERE a > 1;
+
+INSERT INTO mt VALUES (1),(2),(3);
+
+SELECT *,_version FROM lv;
+SELECT *,_version FROM lv;
+
+INSERT INTO mt VALUES (1),(2),(3);
+
+SELECT *,_version FROM lv;
+SELECT *,_version FROM lv;
+
+DROP TABLE lv;
+DROP TABLE mt;