MaterializedMySQL: Add support of double quoted comments

src/Parsers/ExpressionElementParsers.cpp

@@ -1900,6 +1900,39 @@ bool ParserSubstitution::parseImpl(Pos & pos, ASTPtr & node, Expected & expected
 }
 
 
+bool ParserMySQLComment::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
+{
+    if (pos->type != TokenType::QuotedIdentifier && pos->type != TokenType::StringLiteral)
+        return false;
+    String s;
+    ReadBufferFromMemory in(pos->begin, pos->size());
+    try
+    {
+        if (pos->type == TokenType::StringLiteral)
+            readQuotedStringWithSQLStyle(s, in);
+        else
+            readDoubleQuotedStringWithSQLStyle(s, in);
+    }
+    catch (const Exception &)
+    {
+        expected.add(pos, "string literal or double quoted string");
+        return false;
+    }
+
+    if (in.count() != pos->size())
+    {
+        expected.add(pos, "string literal or double quoted string");
+        return false;
+    }
+
+    auto literal = std::make_shared<ASTLiteral>(s);
+    literal->begin = pos;
+    literal->end = ++pos;
+    node = literal;
+    return true;
+}
+
+
 bool ParserMySQLGlobalVariable::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
 {
     if (pos->type != TokenType::DoubleAt)

src/Parsers/ExpressionElementParsers.h

@@ -367,6 +367,21 @@ protected:
 };
 
 
+/** MySQL comment:
+  *  CREATE TABLE t (
+  *  i INT PRIMARY KEY,
+  *  first_name VARCHAR(255) COMMENT 'FIRST_NAME',
+  *  last_name VARCHAR(255) COMMENT "LAST_NAME"
+  *  )
+  */
+class ParserMySQLComment : public IParserBase
+{
+protected:
+    const char * getName() const override { return "MySQL comment parser"; }
+    bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) override;
+};
+
+
 /** MySQL-style global variable: @@var
   */
 class ParserMySQLGlobalVariable : public IParserBase

src/Parsers/MySQL/ASTDeclareColumn.cpp

@@ -50,7 +50,7 @@ static inline bool parseColumnDeclareOptions(IParser::Pos & pos, ASTPtr & node,
             OptionDescribe("PRIMARY KEY", "primary_key", std::make_unique<ParserAlwaysTrue>()),
             OptionDescribe("UNIQUE", "unique_key", std::make_unique<ParserAlwaysTrue>()),
             OptionDescribe("KEY", "primary_key", std::make_unique<ParserAlwaysTrue>()),
-            OptionDescribe("COMMENT", "comment", std::make_unique<ParserStringLiteral>()),
+            OptionDescribe("COMMENT", "comment", std::make_unique<ParserMySQLComment>()),
             OptionDescribe("CHARACTER SET", "charset_name", std::make_unique<ParserCharsetOrCollateName>()),
              OptionDescribe("CHARSET", "charset", std::make_unique<ParserCharsetOrCollateName>()),
             OptionDescribe("COLLATE", "collate", std::make_unique<ParserCharsetOrCollateName>()),

tests/integration/test_materialized_mysql_database/materialized_with_ddl.py

@@ -1617,6 +1617,41 @@ def materialized_with_column_comments_test(clickhouse_node, mysql_node, service_
     mysql_node.query("DROP DATABASE materialized_with_column_comments_test")
 
 
+def double_quoted_comment(clickhouse_node, mysql_node, service_name):
+    db = "comment_db"
+    mysql_node.query(f"DROP DATABASE IF EXISTS {db}")
+    clickhouse_node.query(f"DROP DATABASE IF EXISTS {db}")
+    mysql_node.query(f"CREATE DATABASE {db}")
+    mysql_node.query(
+        f'CREATE TABLE {db}.t1 (i INT PRIMARY KEY, id VARCHAR(255) COMMENT "ID")'
+    )
+    mysql_node.query(
+        f"CREATE TABLE {db}.t2 (i INT PRIMARY KEY, id VARCHAR(255) COMMENT 'ID')"
+    )
+    clickhouse_node.query(
+        f"CREATE DATABASE {db} ENGINE = MaterializedMySQL('{service_name}:3306', '{db}', 'root', 'clickhouse')"
+    )
+    check_query(
+        clickhouse_node,
+        f"SHOW TABLES FROM {db} FORMAT TSV",
+        "t1\nt2\n",
+    )
+
+    # incremental
+    mysql_node.query(
+        f'CREATE TABLE {db}.t3 (i INT PRIMARY KEY, id VARCHAR(255) COMMENT "ID")'
+    )
+    mysql_node.query(
+        f"CREATE TABLE {db}.t4 (i INT PRIMARY KEY, id VARCHAR(255) COMMENT 'ID')"
+    )
+    check_query(
+        clickhouse_node, f"SHOW TABLES FROM {db} FORMAT TSV", "t1\nt2\nt3\nt4\n"
+    )
+
+    clickhouse_node.query(f"DROP DATABASE IF EXISTS {db}")
+    mysql_node.query(f"DROP DATABASE IF EXISTS {db}")
+
+
 def materialized_with_enum8_test(clickhouse_node, mysql_node, service_name):
     mysql_node.query("DROP DATABASE IF EXISTS materialized_with_enum8_test")
     clickhouse_node.query("DROP DATABASE IF EXISTS materialized_with_enum8_test")

tests/integration/test_materialized_mysql_database/test.py

@@ -416,6 +416,12 @@ def test_materialized_with_column_comments(
     )
 
 
+def test_double_quoted_comment(started_cluster, started_mysql_8_0, clickhouse_node):
+    materialized_with_ddl.double_quoted_comment(
+        clickhouse_node, started_mysql_8_0, "mysql80"
+    )
+
+
 def test_materialized_with_enum(
     started_cluster, started_mysql_8_0, started_mysql_5_7, clickhouse_node
 ):