Backport #46831 to 23.2: Allow PREWHERE for Merge with different DEFAULT expression for column

src/Storages/StorageMerge.cpp

@@ -44,6 +44,27 @@
 #include <algorithm>
 
 
+namespace
+{
+
+using namespace DB;
+bool columnIsPhysical(ColumnDefaultKind kind)
+{
+    return kind == ColumnDefaultKind::Default || kind == ColumnDefaultKind::Materialized;
+}
+bool columnDefaultKindHasSameType(ColumnDefaultKind lhs, ColumnDefaultKind rhs)
+{
+    if (lhs == rhs)
+        return true;
+
+    if (columnIsPhysical(lhs) == columnIsPhysical(rhs))
+        return true;
+
+    return false;
+}
+
+}
+
 namespace DB
 {
 
@@ -172,11 +193,13 @@ std::optional<NameSet> StorageMerge::supportedPrewhereColumns() const
 
     NameSet supported_columns;
 
-    std::unordered_map<std::string, std::pair<const IDataType *, std::optional<ColumnDefault>>> column_type_default;
+    std::unordered_map<std::string, std::pair<const IDataType *, ColumnDefaultKind>> column_info;
     for (const auto & name_type : columns.getAll())
     {
-        column_type_default.emplace(name_type.name, std::make_pair(
-            name_type.type.get(), columns.getDefault(name_type.name)));
+        const auto & column_default = columns.getDefault(name_type.name).value_or(ColumnDefault{});
+        column_info.emplace(name_type.name, std::make_pair(
+            name_type.type.get(),
+            column_default.kind));
         supported_columns.emplace(name_type.name);
     }
 
@@ -191,11 +214,10 @@ std::optional<NameSet> StorageMerge::supportedPrewhereColumns() const
         const auto & table_columns = table_metadata_ptr->getColumns();
         for (const auto & column : table_columns.getAll())
         {
-            const auto & root_type_default = column_type_default[column.name];
-            const IDataType * root_type = root_type_default.first;
-            const std::optional<ColumnDefault> & src_default = root_type_default.second;
+            const auto & column_default = table_columns.getDefault(column.name).value_or(ColumnDefault{});
+            const auto & [root_type, src_default_kind] = column_info[column.name];
             if ((root_type && !root_type->equals(*column.type)) ||
-                src_default != table_columns.getDefault(column.name))
+                !columnDefaultKindHasSameType(src_default_kind, column_default.kind))
             {
                 supported_columns.erase(column.name);
             }

tests/queries/0_stateless/02575_merge_prewhere_default_expression.reference

@@ -0,0 +1,8 @@
+-- { echoOn }
+SELECT * FROM m PREWHERE a = 'OK' ORDER BY a, f;
+OK	1
+OK	2
+SELECT * FROM m PREWHERE f = 1 ORDER BY a, f;
+OK	1
+SELECT * FROM m WHERE f = 0 SETTINGS optimize_move_to_prewhere=0;
+SELECT * FROM m WHERE f = 0 SETTINGS optimize_move_to_prewhere=1;

tests/queries/0_stateless/02575_merge_prewhere_default_expression.sql

@@ -0,0 +1,38 @@
+-- Allow PREWHERE when Merge() and MergeTree has different DEFAULT expression
+
+DROP TABLE IF EXISTS m;
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+
+CREATE TABLE m
+(
+    `a` String,
+    `f` UInt8 DEFAULT 0
+)
+ENGINE = Merge(currentDatabase(), '^(t1|t2)$');
+
+CREATE TABLE t1
+(
+    a String,
+    f UInt8 DEFAULT 1
+)
+ENGINE = MergeTree
+ORDER BY tuple()
+SETTINGS index_granularity = 8192;
+INSERT INTO t1 (a) VALUES ('OK');
+
+CREATE TABLE t2
+(
+    a String,
+    f UInt8 DEFAULT 2
+)
+ENGINE = MergeTree
+ORDER BY tuple()
+SETTINGS index_granularity = 8192;
+INSERT INTO t2 (a) VALUES ('OK');
+
+-- { echoOn }
+SELECT * FROM m PREWHERE a = 'OK' ORDER BY a, f;
+SELECT * FROM m PREWHERE f = 1 ORDER BY a, f;
+SELECT * FROM m WHERE f = 0 SETTINGS optimize_move_to_prewhere=0;
+SELECT * FROM m WHERE f = 0 SETTINGS optimize_move_to_prewhere=1;

tests/queries/0_stateless/02570_merge_alias_prewhere.sql → tests/queries/0_stateless/02575_merge_prewhere_different_default_kind.sql

@@ -1,3 +1,5 @@
+-- Prohibit PREWHERE when Merge and MergeTree has different default type of the column
+
 DROP TABLE IF EXISTS m;
 DROP TABLE IF EXISTS t1;
 DROP TABLE IF EXISTS t2;

tests/queries/0_stateless/02575_merge_prewhere_ephemeral.reference

@@ -0,0 +1,11 @@
+-- { echoOn }
+SELECT * FROM m PREWHERE a = 'OK' ORDER BY a;
+OK
+OK
+SELECT * FROM m PREWHERE f = 1 ORDER BY a; -- { serverError ILLEGAL_PREWHERE }
+SELECT * FROM m WHERE a = 'OK' SETTINGS optimize_move_to_prewhere=0;
+OK
+OK
+SELECT * FROM m WHERE a = 'OK' SETTINGS optimize_move_to_prewhere=1;
+OK
+OK

tests/queries/0_stateless/02575_merge_prewhere_ephemeral.sql

@@ -0,0 +1,38 @@
+-- You cannot query EPHEMERAL
+
+DROP TABLE IF EXISTS m;
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+
+CREATE TABLE m
+(
+    `a` String,
+    `f` UInt8 EPHEMERAL 0
+)
+ENGINE = Merge(currentDatabase(), '^(t1|t2)$');
+
+CREATE TABLE t1
+(
+    a String,
+    f UInt8 DEFAULT 1
+)
+ENGINE = MergeTree
+ORDER BY tuple()
+SETTINGS index_granularity = 8192;
+INSERT INTO t1 (a) VALUES ('OK');
+
+CREATE TABLE t2
+(
+    a String,
+    f UInt8 DEFAULT 2
+)
+ENGINE = MergeTree
+ORDER BY tuple()
+SETTINGS index_granularity = 8192;
+INSERT INTO t2 (a) VALUES ('OK');
+
+-- { echoOn }
+SELECT * FROM m PREWHERE a = 'OK' ORDER BY a;
+SELECT * FROM m PREWHERE f = 1 ORDER BY a; -- { serverError ILLEGAL_PREWHERE }
+SELECT * FROM m WHERE a = 'OK' SETTINGS optimize_move_to_prewhere=0;
+SELECT * FROM m WHERE a = 'OK' SETTINGS optimize_move_to_prewhere=1;

tests/queries/0_stateless/02575_merge_prewhere_materialized.reference

@@ -0,0 +1,8 @@
+-- { echoOn }
+SELECT * FROM m PREWHERE a = 'OK' ORDER BY a, f;
+OK	1
+OK	2
+SELECT * FROM m PREWHERE f = 1 ORDER BY a, f;
+OK	1
+SELECT * FROM m WHERE f = 0 SETTINGS optimize_move_to_prewhere=0;
+SELECT * FROM m WHERE f = 0 SETTINGS optimize_move_to_prewhere=1;

tests/queries/0_stateless/02575_merge_prewhere_materialized.sql

@@ -0,0 +1,43 @@
+-- Allow PREWHERE when Merge has DEFAULT and MergeTree has MATERIALIZED
+
+DROP TABLE IF EXISTS m;
+DROP TABLE IF EXISTS t1;
+DROP TABLE IF EXISTS t2;
+
+CREATE TABLE m
+(
+    `a` String,
+    `f` UInt8 DEFAULT 0
+)
+ENGINE = Merge(currentDatabase(), '^(t1|t2)$');
+
+CREATE TABLE t1
+(
+    a String,
+    f UInt8 MATERIALIZED 1
+)
+ENGINE = MergeTree
+ORDER BY tuple()
+SETTINGS index_granularity = 8192;
+INSERT INTO t1 (a) VALUES ('OK');
+
+CREATE TABLE t2
+(
+    a String,
+    f UInt8 DEFAULT 2
+)
+ENGINE = MergeTree
+ORDER BY tuple()
+SETTINGS index_granularity = 8192;
+INSERT INTO t2 (a) VALUES ('OK');
+
+-- { echoOn }
+SELECT * FROM m PREWHERE a = 'OK' ORDER BY a, f;
+SELECT * FROM m PREWHERE f = 1 ORDER BY a, f;
+SELECT * FROM m WHERE f = 0 SETTINGS optimize_move_to_prewhere=0;
+SELECT * FROM m WHERE f = 0 SETTINGS optimize_move_to_prewhere=1;
+-- { echoOff }
+
+DROP TABLE m;
+DROP TABLE t1;
+DROP TABLE t2;