Modify Materialized View query

dbms/src/DataStreams/PushingToViewsBlockOutputStream.cpp

@@ -8,7 +8,6 @@
 #include <Parsers/ASTInsertQuery.h>
 #include <Common/CurrentThread.h>
 #include <Common/setThreadName.h>
-#include <Common/getNumberOfPhysicalCPUCores.h>
 #include <Common/ThreadPool.h>
 #include <Storages/MergeTree/ReplicatedMergeTreeBlockOutputStream.h>
 #include <Storages/StorageValues.h>
@@ -51,8 +50,10 @@ PushingToViewsBlockOutputStream::PushingToViewsBlockOutputStream(
         ASTPtr query;
         BlockOutputStreamPtr out;
 
-        if (auto * materialized_view = dynamic_cast<const StorageMaterializedView *>(dependent_table.get()))
+        if (auto * materialized_view = dynamic_cast<StorageMaterializedView *>(dependent_table.get()))
         {
+            addTableLock(materialized_view->lockStructureForShare(true, context.getInitialQueryId()));
+
             StoragePtr inner_table = materialized_view->getTargetTable();
             auto inner_table_id = inner_table->getStorageID();
             query = materialized_view->getInnerQuery();

dbms/src/Databases/DatabaseOrdinary.cpp

@@ -252,20 +252,23 @@ void DatabaseOrdinary::alterTable(
         ast->replace(ast_create_query.select, metadata.select);
     }
 
-    ASTStorage & storage_ast = *ast_create_query.storage;
-    /// ORDER BY may change, but cannot appear, it's required construction
-    if (metadata.order_by_ast && storage_ast.order_by)
-        storage_ast.set(storage_ast.order_by, metadata.order_by_ast);
+    /// MaterializedView is one type of CREATE query without storage.
+    if (ast_create_query.storage)
+    {
+        ASTStorage & storage_ast = *ast_create_query.storage;
+        /// ORDER BY may change, but cannot appear, it's required construction
+        if (metadata.order_by_ast && storage_ast.order_by)
+            storage_ast.set(storage_ast.order_by, metadata.order_by_ast);
 
-    if (metadata.primary_key_ast)
-        storage_ast.set(storage_ast.primary_key, metadata.primary_key_ast);
+        if (metadata.primary_key_ast)
+            storage_ast.set(storage_ast.primary_key, metadata.primary_key_ast);
 
-    if (metadata.ttl_for_table_ast)
-        storage_ast.set(storage_ast.ttl_table, metadata.ttl_for_table_ast);
-
-    if (metadata.settings_ast)
-        storage_ast.set(storage_ast.settings, metadata.settings_ast);
+        if (metadata.ttl_for_table_ast)
+            storage_ast.set(storage_ast.ttl_table, metadata.ttl_for_table_ast);
 
+        if (metadata.settings_ast)
+            storage_ast.set(storage_ast.settings, metadata.settings_ast);
+    }
 
     statement = getObjectDefinitionFromCreateQuery(ast);
     {

dbms/src/Storages/StorageMaterializedView.cpp

@@ -37,7 +37,7 @@ static inline String generateInnerTableName(const String & table_name)
     return ".inner." + table_name;
 }
 
-static StorageID extractDependentTableFromSelectQuery(ASTSelectQuery & query, Context & context, bool add_default_db = true)
+static StorageID extractDependentTableFromSelectQuery(ASTSelectQuery & query, const Context & context, bool add_default_db = true)
 {
     if (add_default_db)
     {
@@ -117,22 +117,23 @@ StorageMaterializedView::StorageMaterializedView(
     inner_query = query.select->list_of_selects->children.at(0);
 
     auto & select_query = inner_query->as<ASTSelectQuery &>();
-    select_table_id = extractDependentTableFromSelectQuery(select_query, local_context);
     checkAllowedQueries(select_query);
 
+    select_table_id = extractDependentTableFromSelectQuery(select_query, local_context);
+
     if (!has_inner_table)
         target_table_id = StorageID(query.to_database, query.to_table);
     else if (attach_)
     {
         /// If there is an ATTACH request, then the internal table must already be created.
-        target_table_id = StorageID(table_id_.database_name, generateInnerTableName(table_id_.table_name));
+        target_table_id = StorageID(getStorageID().database_name, generateInnerTableName(getStorageID().table_name));
     }
     else
     {
         /// We will create a query to create an internal table.
         auto manual_create_query = std::make_shared<ASTCreateQuery>();
-        manual_create_query->database = table_id_.database_name;
-        manual_create_query->table = generateInnerTableName(table_id_.table_name);
+        manual_create_query->database = getStorageID().database_name;
+        manual_create_query->table = generateInnerTableName(getStorageID().table_name);
 
         auto new_columns_list = std::make_shared<ASTColumns>();
         new_columns_list->set(new_columns_list->columns, query.columns_list->columns->ptr());
@@ -148,7 +149,7 @@ StorageMaterializedView::StorageMaterializedView(
     }
 
     if (!select_table_id.empty())
-        global_context.addDependency(select_table_id, table_id_);
+        global_context.addDependency(select_table_id, getStorageID());
 }
 
 NameAndTypePair StorageMaterializedView::getColumn(const String & column_name) const
@@ -261,6 +262,37 @@ void StorageMaterializedView::alter(
     auto table_id = getStorageID();
     StorageInMemoryMetadata metadata = getInMemoryMetadata();
     params.apply(metadata);
+
+    /// start modify query
+    if (context.getSettingsRef().allow_experimental_alter_materialized_view_structure)
+    {
+        auto & new_select = metadata.select->as<ASTSelectWithUnionQuery &>();
+
+        if (new_select.list_of_selects->children.size() != 1)
+            throw Exception("UNION is not supported for MATERIALIZED VIEW", ErrorCodes::QUERY_IS_NOT_SUPPORTED_IN_MATERIALIZED_VIEW);
+
+        auto & new_inner_query = new_select.list_of_selects->children.at(0);
+        auto & select_query = new_inner_query->as<ASTSelectQuery &>();
+        checkAllowedQueries(select_query);
+
+        auto new_select_table_id = extractDependentTableFromSelectQuery(select_query, context);
+
+        {
+            auto context_lock = global_context.getLock();
+
+            if (!select_table_id.empty())
+                global_context.removeDependency(select_table_id, getStorageID());
+
+            if (!new_select_table_id.empty())
+                global_context.addDependency(new_select_table_id, getStorageID());
+
+            select_table_id = new_select_table_id;
+            select = metadata.select;
+            inner_query = new_inner_query;
+        }
+    }
+    /// end modify query
+
     context.getDatabase(table_id.database_name)->alterTable(context, table_id.table_name, metadata);
     setColumns(std::move(metadata.columns));
 }
@@ -270,7 +302,13 @@ void StorageMaterializedView::checkAlterIsPossible(const AlterCommands & command
 {
     if (settings.allow_experimental_alter_materialized_view_structure)
     {
-        throw Exception("work in progress", ErrorCodes::NOT_IMPLEMENTED);
+        for (const auto & command : commands)
+        {
+            if (!command.isCommentAlter() && command.type != AlterCommand::MODIFY_QUERY)
+                throw Exception(
+                    "Alter of type '" + alterTypeToString(command.type) + "' is not supported by storage " + getName(),
+                    ErrorCodes::NOT_IMPLEMENTED);
+        }
     }
     else
     {

dbms/tests/queries/0_stateless/01019_alter_materialized_view_atomic.reference

@@ -0,0 +1 @@
+100

dbms/tests/queries/0_stateless/01019_alter_materialized_view_atomic.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+
+set -e
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+. $CURDIR/../shell_config.sh
+
+$CLICKHOUSE_CLIENT --multiquery <<EOF
+DROP TABLE IF EXISTS src;
+DROP TABLE IF EXISTS mv;
+
+CREATE TABLE src(v UInt64) ENGINE = Null;
+CREATE MATERIALIZED VIEW mv(v UInt8) Engine = MergeTree() ORDER BY v AS SELECT v FROM src;
+EOF
+
+# Test that ALTER doesn't cause data loss or duplication.
+#
+# Idea for future:
+#
+#    null
+#  /      \
+# mv1    mv2
+#  \      /
+#   \    /
+#   mv sink
+#
+# Insert N times into null while altering sink query and switching it from mv1 to mv2.
+
+function alter_thread()
+{
+  trap 'exit' INT
+
+  ALTERS[0]="ALTER TABLE mv MODIFY QUERY SELECT v FROM src;"
+  ALTERS[1]="ALTER TABLE mv MODIFY QUERY SELECT v * 2 as v FROM src;"
+
+  while true; do
+    $CLICKHOUSE_CLIENT --allow_experimental_alter_materialized_view_structure=1 -q "${ALTERS[$RANDOM % 2]}"
+    sleep `echo 0.$RANDOM`;
+  done
+}
+
+alter_thread &
+alter_pid=$!
+
+for i in $(seq 1 100); do
+  (
+    # Retry (hopefully retriable (deadlock avoided)) errors.
+    until false; do
+      $CLICKHOUSE_CLIENT -q "INSERT INTO src VALUES (1);" 2>/dev/null && break
+    done
+  )
+done
+
+# Enough alters.
+kill -INT $alter_pid
+
+wait
+
+# This was a fun ride.
+$CLICKHOUSE_CLIENT -q "SELECT count() FROM mv;"

dbms/tests/queries/0_stateless/01019_alter_materialized_view_consistent.reference

@@ -0,0 +1 @@
+inconsistencies	0

dbms/tests/queries/0_stateless/01019_alter_materialized_view_consistent.sh

@@ -0,0 +1,75 @@
+#!/usr/bin/env bash
+
+set -e
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+. $CURDIR/../shell_config.sh
+
+$CLICKHOUSE_CLIENT --multiquery <<EOF
+DROP TABLE IF EXISTS src_a;
+DROP TABLE IF EXISTS src_b;
+
+DROP TABLE IF EXISTS mv;
+
+CREATE TABLE src_a(v UInt64) ENGINE = Null;
+CREATE TABLE src_b(v UInt64) ENGINE = Null;
+
+CREATE MATERIALIZED VIEW mv(test UInt8, case UInt8)
+Engine = MergeTree()
+ORDER BY test AS
+SELECT v == 1 as test, v as case FROM src_a;
+EOF
+
+# The purpose of this test is to ensure that MV query A is always used against source table A. Same for query/table B.
+# Also, helps detect data races.
+
+function insert_thread() {
+  trap 'exit' INT
+
+  INSERT[0]="INSERT INTO TABLE src_a VALUES (1);"
+  INSERT[1]="INSERT INTO TABLE src_b VALUES (2);"
+
+  while true; do
+    # trigger 100 concurrent inserts at a time
+    for i in $(seq 1 100); do
+      # ignore `Possible deadlock avoided. Client should retry`
+      $CLICKHOUSE_CLIENT -q "${INSERT[$RANDOM % 2]}" 2>/dev/null &
+    done
+
+    wait
+  done
+}
+
+function alter_thread() {
+  trap 'exit' INT
+
+  ALTER[0]="ALTER TABLE mv MODIFY QUERY SELECT v == 1 as test, v as case FROM src_a;"
+  ALTER[1]="ALTER TABLE mv MODIFY QUERY SELECT v == 2 as test, v as case FROM src_b;"
+
+  while true; do
+    $CLICKHOUSE_CLIENT --allow_experimental_alter_materialized_view_structure=1 \
+      -q "${ALTER[$RANDOM % 2]}"
+    sleep "0.0$RANDOM"
+  done
+}
+
+insert_thread &
+insert_thread_pid=$!
+
+alter_thread &
+alter_thread_pid=$!
+
+while true; do
+  is_done=$($CLICKHOUSE_CLIENT -q "SELECT countIf(case = 1) > 0 AND countIf(case = 2) > 0 FROM mv;")
+
+  if [ "$is_done" -eq "1" ]; then
+    break
+  fi
+done
+
+kill -INT $insert_thread_pid
+kill -INT $alter_thread_pid
+
+wait
+
+$CLICKHOUSE_CLIENT -q "SELECT 'inconsistencies', count() FROM mv WHERE test == 0;"

dbms/tests/queries/0_stateless/01019_alter_materialized_view_query.reference

@@ -1,13 +1,13 @@
 1
-1
 2
 2
 3
-3
-1	0
+4
+6
 1	0
 2	0
 2	0
 3	0
-3	0
-42	0
+4	0
+6	0
+84	1

dbms/tests/queries/0_stateless/01019_alter_materialized_view_query.sql

@@ -1,5 +1,3 @@
--- Just testing syntax for now.
-
 DROP TABLE IF EXISTS src;
 DROP TABLE IF EXISTS dest;
 DROP TABLE IF EXISTS pipe;
@@ -15,13 +13,12 @@ INSERT INTO src VALUES (1), (2), (3);
 SET allow_experimental_alter_materialized_view_structure = 1;
 
 -- Live alter which changes query logic and adds an extra column.
--- This is not implemented yet and this test is just a draft.
 ALTER TABLE pipe
     MODIFY QUERY
     SELECT
         v * 2 as v,
         1 as v2
-    FROM src; -- { serverError 48 }
+    FROM src;
 
 INSERT INTO src VALUES (1), (2), (3);