Merge branch 'master' into ucasFL-fix

docs/_description_templates/template-system-table.md

@@ -1,4 +1,4 @@
-## system.table_name {#system-tables_table-name}
+# system.table_name {#system-tables_table-name}
 
 Description.
 

docs/en/engines/database-engines/index.md

@@ -16,4 +16,6 @@ You can also use the following database engines:
 
 -   [Lazy](../../engines/database-engines/lazy.md)
 
+-   [MaterializeMySQL](../../engines/database-engines/materialize-mysql.md)
+
 [Original article](https://clickhouse.tech/docs/en/database_engines/) <!--hide-->

docs/en/engines/database-engines/materialize-mysql.md

@@ -0,0 +1,156 @@
+---
+toc_priority: 29
+toc_title: MaterializeMySQL
+---
+
+# MaterializeMySQL {#materialize-mysql}
+
+ Creates ClickHouse database with all the tables existing in MySQL, and all the data in those tables. 
+
+ ClickHouse server works as MySQL replica. It reads binlog and performs DDL and DML queries.   
+
+## Creating a Database {#creating-a-database}
+
+``` sql
+CREATE DATABASE [IF NOT EXISTS] db_name [ON CLUSTER cluster]
+ENGINE = MaterializeMySQL('host:port', ['database' | database], 'user', 'password') [SETTINGS ...]
+```
+
+**Engine Parameters**
+
+-   `host:port` — MySQL server endpoint.
+-   `database` — MySQL database name.
+-   `user` — MySQL user.
+-   `password` — User password.
+
+## Virtual columns {#virtual-columns}
+
+ When working with the `MaterializeMySQL` database engine, [ReplacingMergeTree](../../engines/table-engines/mergetree-family/replacingmergetree.md) tables are used with virtual `_sign` and `_version` columns.
+ 
+ - `_version` — Transaction counter. Type [UInt64](../../sql-reference/data-types/int-uint.md). 
+ - `_sign` — Deletion mark. Type [Int8](../../sql-reference/data-types/int-uint.md). Possible values: 
+     - `1` — Row is not deleted, 
+     - `-1` — Row is deleted.
+
+## Data Types Support {#data_types-support}
+
+| MySQL                   | ClickHouse                                                   |
+|-------------------------|--------------------------------------------------------------|
+| TINY                    | [Int8](../../sql-reference/data-types/int-uint.md)           |
+| SHORT                   | [Int16](../../sql-reference/data-types/int-uint.md)          |
+| INT24                   | [Int32](../../sql-reference/data-types/int-uint.md)          |
+| LONG                    | [UInt32](../../sql-reference/data-types/int-uint.md)         |
+| LONGLONG                | [UInt64](../../sql-reference/data-types/int-uint.md)         |
+| FLOAT                   | [Float32](../../sql-reference/data-types/float.md)           |
+| DOUBLE                  | [Float64](../../sql-reference/data-types/float.md)           |
+| DECIMAL, NEWDECIMAL     | [Decimal](../../sql-reference/data-types/decimal.md)         |
+| DATE, NEWDATE           | [Date](../../sql-reference/data-types/date.md)               |
+| DATETIME, TIMESTAMP     | [DateTime](../../sql-reference/data-types/datetime.md)       |
+| DATETIME2, TIMESTAMP2   | [DateTime64](../../sql-reference/data-types/datetime64.md)   |
+| STRING                  | [String](../../sql-reference/data-types/string.md)           |
+| VARCHAR, VAR_STRING     | [String](../../sql-reference/data-types/string.md)           |
+| BLOB                    | [String](../../sql-reference/data-types/string.md)           |
+
+Other types are not supported. If MySQL table contains a column of such type, ClickHouse throws exception "Unhandled data type" and stops replication.
+
+[Nullable](../../sql-reference/data-types/nullable.md) is supported.
+
+## Specifics and Recommendations {#specifics-and-recommendations}
+
+### DDL Queries {#ddl-queries}
+
+MySQL DDL queries are converted into the corresponding ClickHouse DDL queries ([ALTER](../../sql-reference/statements/alter/index.md), [CREATE](../../sql-reference/statements/create/index.md), [DROP](../../sql-reference/statements/drop.md), [RENAME](../../sql-reference/statements/rename.md)). If ClickHouse cannot parse some DDL query, the query is ignored.
+
+###  Data Replication {#data-replication}
+
+MaterializeMySQL does not support direct `INSERT`, `DELETE` and `UPDATE` queries. However, they are supported in terms of data replication:
+
+- MySQL `INSERT` query is converted into `INSERT` with `_sign=1`.
+
+- MySQl `DELETE` query is converted into `INSERT` with `_sign=-1`. 
+
+- MySQL `UPDATE` query is converted into `INSERT` with `_sign=-1` and `INSERT` with `_sign=1`.
+
+### Selecting from MaterializeMySQL Tables {#select}
+
+`SELECT` query form MaterializeMySQL tables has some specifics:
+
+- If `_version` is not specified in the `SELECT` query, [FINAL](../../sql-reference/statements/select/from.md#select-from-final) modifier is used. So only rows with `MAX(_version)` are selected.
+
+- If `_sign` is not specified in the `SELECT` query, `WHERE _sign=1` is used by default, so the deleted rows are not included into the result set. 
+
+### Index Conversion {#index-conversion}
+
+MySQL `PRIMARY KEY` and `INDEX` clauses are converted into `ORDER BY` tuples in ClickHouse tables.
+
+ClickHouse has only one physical order, which is determined by `ORDER BY` clause. To create a new physical order, use [materialized views](../../sql-reference/statements/create/view.md#materialized).
+
+ **Notes**
+
+ - Rows with `_sign=-1` are not deleted physically from the tables. 
+ - Cascade `UPDATE/DELETE` queries are not supported by the `MaterializeMySQL` engine.
+ - Replication can be easily broken.
+ - Manual operations on database and tables are forbidden.
+
+## Examples of Use {#examples-of-use}
+
+Queries in MySQL:
+
+``` sql
+mysql> CREATE DATABASE db;
+mysql> CREATE TABLE db.test (a INT PRIMARY KEY, b INT);
+mysql> INSERT INTO db.test VALUES (1, 11), (2, 22);
+mysql> DELETE FROM db.test WHERE a=1;
+mysql> ALTER TABLE db.test ADD COLUMN c VARCHAR(16);
+mysql> UPDATE db.test SET c='Wow!', b=222;
+mysql> SELECT * FROM test;
+```
+```text
++---+------+------+ 
+| a |    b |    c |
++---+------+------+ 
+| 2 |  222 | Wow! |
++---+------+------+
+```
+
+Database in ClickHouse, exchanging data with the MySQL server:
+
+The database and the table created:
+
+``` sql
+CREATE DATABASE mysql ENGINE = MaterializeMySQL('localhost:3306', 'db', 'user', '***');
+SHOW TABLES FROM mysql;
+```
+
+``` text
+┌─name─┐
+│ test │
+└──────┘
+```
+
+After inserting data:
+
+``` sql
+SELECT * FROM mysql.test;
+```
+
+``` text
+┌─a─┬──b─┐ 
+│ 1 │ 11 │ 
+│ 2 │ 22 │ 
+└───┴────┘
+```
+
+After deleting data, adding the column and updating:
+
+``` sql
+SELECT * FROM mysql.test;
+```
+
+``` text
+┌─a─┬───b─┬─c────┐ 
+│ 2 │ 222 │ Wow! │ 
+└───┴─────┴──────┘
+```
+
+[Original article](https://clickhouse.tech/docs/en/database_engines/materialize-mysql/) <!--hide-->

docs/en/interfaces/cli.md

@@ -11,9 +11,9 @@ ClickHouse provides a native command-line client: `clickhouse-client`. The clien
 
 ``` bash
 $ clickhouse-client
-ClickHouse client version 19.17.1.1579 (official build).
+ClickHouse client version 20.13.1.5273 (official build).
 Connecting to localhost:9000 as user default.
-Connected to ClickHouse server version 19.17.1 revision 54428.
+Connected to ClickHouse server version 20.13.1 revision 54442.
 
 :)
 ```
@@ -127,6 +127,8 @@ You can pass parameters to `clickhouse-client` (all parameters have a default va
 -   `--history_file` — Path to a file containing command history.
 -   `--param_<name>` — Value for a [query with parameters](#cli-queries-with-parameters).
 
+Since version 20.5, `clickhouse-client` has automatic syntax highlighting (always enabled).
+
 ### Configuration Files {#configuration_files}
 
 `clickhouse-client` uses the first existing file of the following:

docs/en/interfaces/third-party/client-libraries.md

@@ -60,5 +60,7 @@ toc_title: Client Libraries
     -   [pillar](https://github.com/sofakingworld/pillar)
 -   Nim
     -   [nim-clickhouse](https://github.com/leonardoce/nim-clickhouse)
+-   Haskell
+    -   [hdbc-clickhouse](https://github.com/zaneli/hdbc-clickhouse)
 
 [Original article](https://clickhouse.tech/docs/en/interfaces/third-party/client_libraries/) <!--hide-->

docs/ru/interfaces/cli.md

@@ -11,9 +11,9 @@ ClickHouse предоставляет собственный клиент ком
 
 ``` bash
 $ clickhouse-client
-ClickHouse client version 19.17.1.1579 (official build).
+ClickHouse client version 20.13.1.5273 (official build).
 Connecting to localhost:9000 as user default.
-Connected to ClickHouse server version 19.17.1 revision 54428.
+Connected to ClickHouse server version 20.13.1 revision 54442.
 
 :)
 ```
@@ -131,6 +131,8 @@ $ clickhouse-client --param_tuple_in_tuple="(10, ('dt', 10))" -q "SELECT * FROM
 -   `--secure` — если указано, будет использован безопасный канал.
 -   `--param_<name>` — значение параметра для [запроса с параметрами](#cli-queries-with-parameters).
 
+Начиная с версии 20.5, в `clickhouse-client` есть автоматическая подсветка синтаксиса (включена всегда).
+
 ### Конфигурационные файлы {#konfiguratsionnye-faily}
 
 `clickhouse—client` использует первый существующий файл из:

tests/queries/0_stateless/01526_client_start_and_exit.sh

@@ -9,7 +9,7 @@ ${CLICKHOUSE_CLIENT} -q "SELECT 'CREATE TABLE test_' || hex(randomPrintableASCII
 function stress()
 {
     while true; do
-        "${CURDIR}"/01526_client_start_and_exit.expect | grep -v -P 'ClickHouse client|Connecting|Connected|:\) Bye\.|^\s*$|spawn bash|^0\s*$'
+        "${CURDIR}"/01526_client_start_and_exit.expect | grep -v -P 'ClickHouse client|Connecting|Connected|:\) Bye\.|new year|^\s*$|spawn bash|^0\s*$'
     done
 }