Copy comment when using CREATE AS statement

src/Interpreters/InterpreterCreateQuery.cpp

@@ -794,6 +794,9 @@ InterpreterCreateQuery::TableProperties InterpreterCreateQuery::getTableProperti
         auto as_storage_metadata = as_storage->getInMemoryMetadataPtr();
         properties.columns = as_storage_metadata->getColumns();
 
+        if (!create.comment && !as_storage_metadata->comment.empty())
+            create.set(create.comment, std::make_shared<ASTLiteral>(as_storage_metadata->comment));
+
         /// Secondary indices and projections make sense only for MergeTree family of storage engines.
         /// We should not copy them for other storages.
         if (create.storage && endsWith(create.storage->engine->name, "MergeTree"))

tests/queries/0_stateless/02904_distributed_settings_background_insert_compatibility.reference

@@ -1,8 +1,8 @@
-CREATE TABLE default.dist_monitor_batch_inserts\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS monitor_batch_inserts = 1
-CREATE TABLE default.dist_monitor_split_batch_on_failure\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS monitor_split_batch_on_failure = 1
-CREATE TABLE default.dist_monitor_sleep_time_ms\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS monitor_sleep_time_ms = 1
-CREATE TABLE default.dist_monitor_max_sleep_time_ms\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS monitor_max_sleep_time_ms = 1
-CREATE TABLE default.dist_background_insert_batch\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS background_insert_batch = 1
-CREATE TABLE default.dist_background_insert_split_batch_on_failure\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS background_insert_split_batch_on_failure = 1
-CREATE TABLE default.dist_background_insert_sleep_time_ms\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS background_insert_sleep_time_ms = 1
-CREATE TABLE default.dist_background_insert_max_sleep_time_ms\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS background_insert_max_sleep_time_ms = 1
+CREATE TABLE default.dist_monitor_batch_inserts\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS monitor_batch_inserts = 1\nCOMMENT \'This table contains a single row with a single dummy UInt8 column containing the value 0. Used when the table is not specified explicitly, for example in queries like `SELECT 1`.\'
+CREATE TABLE default.dist_monitor_split_batch_on_failure\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS monitor_split_batch_on_failure = 1\nCOMMENT \'This table contains a single row with a single dummy UInt8 column containing the value 0. Used when the table is not specified explicitly, for example in queries like `SELECT 1`.\'
+CREATE TABLE default.dist_monitor_sleep_time_ms\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS monitor_sleep_time_ms = 1\nCOMMENT \'This table contains a single row with a single dummy UInt8 column containing the value 0. Used when the table is not specified explicitly, for example in queries like `SELECT 1`.\'
+CREATE TABLE default.dist_monitor_max_sleep_time_ms\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS monitor_max_sleep_time_ms = 1\nCOMMENT \'This table contains a single row with a single dummy UInt8 column containing the value 0. Used when the table is not specified explicitly, for example in queries like `SELECT 1`.\'
+CREATE TABLE default.dist_background_insert_batch\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS background_insert_batch = 1\nCOMMENT \'This table contains a single row with a single dummy UInt8 column containing the value 0. Used when the table is not specified explicitly, for example in queries like `SELECT 1`.\'
+CREATE TABLE default.dist_background_insert_split_batch_on_failure\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS background_insert_split_batch_on_failure = 1\nCOMMENT \'This table contains a single row with a single dummy UInt8 column containing the value 0. Used when the table is not specified explicitly, for example in queries like `SELECT 1`.\'
+CREATE TABLE default.dist_background_insert_sleep_time_ms\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS background_insert_sleep_time_ms = 1\nCOMMENT \'This table contains a single row with a single dummy UInt8 column containing the value 0. Used when the table is not specified explicitly, for example in queries like `SELECT 1`.\'
+CREATE TABLE default.dist_background_insert_max_sleep_time_ms\n(\n    `dummy` UInt8\n)\nENGINE = Distributed(\'test_shard_localhost\', \'system\', \'one\')\nSETTINGS background_insert_max_sleep_time_ms = 1\nCOMMENT \'This table contains a single row with a single dummy UInt8 column containing the value 0. Used when the table is not specified explicitly, for example in queries like `SELECT 1`.\'

tests/queries/0_stateless/03033_create_as_copies_comment.reference

@@ -0,0 +1,3 @@
+original comment
+original comment
+new comment

tests/queries/0_stateless/03033_create_as_copies_comment.sql

@@ -0,0 +1,11 @@
+DROP TABLE IF EXISTS base;
+DROP TABLE IF EXISTS copy_without_comment;
+DROP TABLE IF EXISTS copy_with_comment;
+
+CREATE TABLE base (a Int32) ENGINE = TinyLog COMMENT 'original comment';
+CREATE TABLE copy_without_comment AS base;
+CREATE TABLE copy_with_comment AS base COMMENT 'new comment';
+
+SELECT comment FROM system.tables WHERE database = currentDatabase() AND name = 'base';
+SELECT comment FROM system.tables WHERE database = currentDatabase() AND name = 'copy_without_comment';
+SELECT comment FROM system.tables WHERE database = currentDatabase() AND name = 'copy_with_comment';