DOCAPI-6207: JDBC engine EN description (#5112)

* DOCAPI-6207: JDBC engine EN description.

* DOCAPI-6207: Edits after review.

docs/en/interfaces/formats.md

@@ -351,7 +351,8 @@ CREATE TABLE IF NOT EXISTS example_table
 - If `input_format_defaults_for_omitted_fields = 0`, then the default value for `x` and `a` equals `0` (as the default value for the `UInt32` data type).
 - If `input_format_defaults_for_omitted_fields = 1`, then the default value for `x` equals `0`, but the default value of `a` equals `x * 2`.
 
-Enabling the option can affect the performance of inserts.
+!!! note "Warning"
+    When inserting data with `insert_sample_with_metadata = 1`, ClickHouse consumes more computational resources, compared to insertion with `insert_sample_with_metadata = 0`.
 
 ### Selecting Data
 

docs/en/operations/table_engines/jdbc.md

@@ -0,0 +1,80 @@
+# JDBC
+
+Allows ClickHouse to connect to external databases via [JDBC](https://en.wikipedia.org/wiki/Java_Database_Connectivity).
+
+To implement JDBC connection, ClickHouse uses the separate program [clickhouse-jdbc-bridge](https://github.com/alex-krash/clickhouse-jdbc-bridge). You should run it as a daemon.
+
+This engine supports the [Nullable](../../data_types/nullable.md) data type.
+
+## Creating a Table
+
+```
+CREATE TABLE [IF NOT EXISTS] [db.]table_name  ENGINE = JDBC(dbms_uri, external_database, external_table)
+```
+
+**Engine Parameters**
+
+- `dbms_uri` — URI of an external DBMS.
+
+    Format: `jdbc:<driver_name>://<host_name>:<port>/?user=<username>&password=<password>`.
+    Example for MySQL: `jdbc:mysql://localhost:3306/?user=root&password=root`.
+
+- `external_database` — Database in an external DBMS.
+- `external_table` — A name of the table in `external_database`.
+
+## Usage Example
+
+Creating a table in MySQL (using native MySQL engine):
+
+```
+mysql> CREATE TABLE `test`.`test` (
+    ->   `int_id` INT NOT NULL AUTO_INCREMENT,
+    ->   `int_nullable` INT NULL DEFAULT NULL,
+    ->   `float` FLOAT NOT NULL,
+    ->   `float_nullable` FLOAT NULL DEFAULT NULL,
+    ->   PRIMARY KEY (`int_id`));
+Query OK, 0 rows affected (0,09 sec)
+
+mysql> insert into test (`int_id`, `float`) VALUES (1,2);
+Query OK, 1 row affected (0,00 sec)
+
+mysql> select * from test;
++--------+--------------+-------+----------------+
+| int_id | int_nullable | float | float_nullable |
++--------+--------------+-------+----------------+
+|      1 |         NULL |     2 |           NULL |
++--------+--------------+-------+----------------+
+1 row in set (0,00 sec)
+```
+
+Selecting data from the table in ClickHouse:
+
+```
+CREATE TABLE jdbc_table ENGINE JDBC('jdbc:mysql://localhost:3306/?user=root&password=root', 'test', 'test')
+
+Ok.
+
+DESCRIBE TABLE jdbc_table
+
+┌─name───────────────┬─type───────────────┬─default_type─┬─default_expression─┐
+│ int_id             │ Int32              │              │                    │
+│ int_nullable       │ Nullable(Int32)    │              │                    │
+│ float              │ Float32            │              │                    │
+│ float_nullable     │ Nullable(Float32)  │              │                    │
+└────────────────────┴────────────────────┴──────────────┴────────────────────┘
+
+10 rows in set. Elapsed: 0.031 sec.
+
+SELECT *
+FROM jdbc_table
+
+┌─int_id─┬─int_nullable─┬─float─┬─float_nullable─┐
+│      1 │         ᴺᵁᴸᴸ │     2 │           ᴺᵁᴸᴸ │
+└────────┴──────────────┴───────┴────────────────┘
+
+1 rows in set. Elapsed: 0.055 sec.
+```
+
+## See Also
+
+- [JDBC table function](../../query_language/table_functions/jdbc.md).

docs/en/operations/table_engines/mergetree.md

@@ -49,7 +49,7 @@ For a description of request parameters, see [request description](../../query_l
 
 **Query clauses**
 
-- `ENGINE` - Name and parameters of the engine. `ENGINE = MergeTree()`. `MergeTree` engine does not have parameters.
+- `ENGINE` — Name and parameters of the engine. `ENGINE = MergeTree()`. `MergeTree` engine does not have parameters.
 
 - `PARTITION BY` — The [partitioning key](custom_partitioning_key.md).
 
@@ -59,7 +59,7 @@ For a description of request parameters, see [request description](../../query_l
 
     A tuple of columns or arbitrary expressions. Example: `ORDER BY (CounterID, EventDate)`.
 
-- `PRIMARY KEY` - The primary key if it [differs from the sorting key](mergetree.md).
+- `PRIMARY KEY` — The primary key if it [differs from the sorting key](mergetree.md).
 
     By default the primary key is the same as the sorting key (which is specified by the `ORDER BY` clause). Thus in most cases it is unnecessary to specify a separate `PRIMARY KEY` clause.
 
@@ -67,7 +67,7 @@ For a description of request parameters, see [request description](../../query_l
 
     If a sampling expression is used, the primary key must contain it. Example: `SAMPLE BY intHash32(UserID) ORDER BY (CounterID, EventDate, intHash32(UserID))`.
 
-- `TTL` - An expression for setting storage time for rows. 
+- `TTL` — An expression for setting storage time for rows.
 
     It must depends on `Date` or `DateTime` column and has one `Date` or `DateTime` column as a result. Example:
     `TTL date + INTERVAL 1 DAY`
@@ -78,7 +78,7 @@ For a description of request parameters, see [request description](../../query_l
     - `index_granularity` — The granularity of an index. The number of data rows between the "marks" of an index. By default, 8192. The list of all available parameters you can see in [MergeTreeSettings.h](https://github.com/yandex/ClickHouse/blob/master/dbms/src/Storages/MergeTree/MergeTreeSettings.h).
     - `use_minimalistic_part_header_in_zookeeper` — Storage method of the data parts headers in ZooKeeper. If  `use_minimalistic_part_header_in_zookeeper=1`, then ZooKeeper stores less data. For more information refer the [setting description](../server_settings/settings.md#server-settings-use_minimalistic_part_header_in_zookeeper) in the "Server configuration parameters" chapter.
     - `min_merge_bytes_to_use_direct_io` — The minimum data volume for merge operation required for using of the direct I/O access to the storage disk. During the merging of the data parts, ClickHouse calculates summary storage volume of all the data to be merged. If the volume exceeds `min_merge_bytes_to_use_direct_io` bytes, then ClickHouse reads and writes the data using direct I/O interface (`O_DIRECT` option) to the storage disk. If `min_merge_bytes_to_use_direct_io = 0`, then the direct I/O is disabled. Default value: `10 * 1024 * 1024 * 1024` bytes.
-    - `merge_with_ttl_timeout` - Minimal time in seconds, when merge with TTL can be repeated. Default value: 86400 (1 day).
+    - `merge_with_ttl_timeout` — Minimal time in seconds, when merge with TTL can be repeated. Default value: 86400 (1 day).
 
 **Example of sections setting**
 
@@ -310,7 +310,7 @@ Reading from a table is automatically parallelized.
 
 ## TTL for columns and tables
 
-Data with expired TTL is removed while executing merges. 
+Data with expired TTL is removed while executing merges.
 
 If TTL is set for column, when it expires, value will be replaced by default. If all values in columns were zeroed in part, data for this column will be deleted from disk for part. You are not allowed to set TTL for all key columns. If TTL is set for table, when it expires, row will be deleted.
 

docs/ru/interfaces/formats.md

@@ -349,7 +349,8 @@ CREATE TABLE IF NOT EXISTS example_table
 - Если `input_format_defaults_for_omitted_fields = 0`, то значение по умолчанию для `x` и `a` равняется `0` (поскольку это значение по умолчанию для типа данных `UInt32`.)
 - Если `input_format_defaults_for_omitted_fields = 1`, то значение по умолчанию для `x` равно `0`, а значение по умолчанию `a` равно `x * 2`.
 
-Включение этой опции может негативно влиять на производительность вставок.
+!!! note "Предупреждение"
+    Если `insert_sample_with_metadata = 1`, то при обработке запросов ClickHouse потребляет больше вычислительных ресурсов, чем если `insert_sample_with_metadata = 0`.
 
 ### Выборка данных
 

docs/toc_en.yml

@@ -91,6 +91,7 @@ nav:
     - 'MaterializedView': 'operations/table_engines/materializedview.md'
     - 'Memory': 'operations/table_engines/memory.md'
     - 'Buffer': 'operations/table_engines/buffer.md'
+    - 'JDBC': 'operations/table_engines/jdbc.md'
 
 - 'SQL Reference':
   - 'hidden': 'query_language/index.md'