Merge pull request #30419 from karnevil13/karnevil-DOCSUP-16354

DOCSUP-16354: Edit and translate to Russian (listen_backlog)
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alexey-milovidov 2021-10-31 22:12:39 +03:00 committed by GitHub
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4 changed files with 30 additions and 14 deletions

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@ -486,16 +486,12 @@ Backlog (queue size of pending connections) of the listen socket.
Default value: `4096` (as in linux [5.4+](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=19f92a030ca6d772ab44b22ee6a01378a8cb32d4)).
Usually this value does not need to be changed, since:
- default value is large enough,
- and for accepting client's connections server has separate thread.
- default value is large enough,
- and for accepting client's connections server has separate thread.
So even if you have `TcpExtListenOverflows` (from `nstat`) non zero and this
counter grows for ClickHouse server it does not mean that this value need to be
increased, since:
- usually if 4096 is not enough it shows some internal ClickHouse scaling
issue, so it is better to report an issue.
- and it does not mean that the server can handle more connections later (and
even if it can, clients can already goes away / disconnect).
So even if you have `TcpExtListenOverflows` (from `nstat`) non zero and this counter grows for ClickHouse server it does not mean that this value need to be increased, since:
- usually if 4096 is not enough it shows some internal ClickHouse scaling issue, so it is better to report an issue.
- and it does not mean that the server can handle more connections later (and even if it could, by that moment clients may be gone or disconnected).
Examples:

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@ -467,6 +467,26 @@ ClickHouse проверяет условия для `min_part_size` и `min_part
<listen_host>127.0.0.1</listen_host>
```
## listen_backlog {#server_configuration_parameters-listen_backlog}
Бэклог (размер очереди соединений, ожидающих принятия) прослушивающего сокета.
Значение по умолчанию: `4096` (как в linux [5.4+](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=19f92a030ca6d772ab44b22ee6a01378a8cb32d4)).
Обычно это значение незачем менять по следующим причинам:
- значение по умолчанию достаточно велико,
- для принятия соединения клиента у сервера есть отдельный поток.
Так что даже если у вас `TcpExtListenOverflows` (из `nstat`) ненулевой и растет для сервера ClickHouse, это не повод увеличивать значение по умолчанию, поскольку:
- обычно если 4096 недостаточно, это говорит о внутренних проблемах ClickHouse с масштабированием, так что лучше сообщить о проблеме,
- и это не значит, что сервер сможет принять еще больше подключений в дальнейшем (а если и сможет, клиенты, вероятно, уже отсоединятся).
Примеры:
``` xml
<listen_backlog>4096</listen_backlog>
```
## logger {#server_configuration_parameters-logger}
Настройки логирования.

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@ -28,7 +28,7 @@ stem('language', word)
Query:
``` sql
SELECT SELECT arrayMap(x -> stem('en', x), ['I', 'think', 'it', 'is', 'a', 'blessing', 'in', 'disguise']) as res;
SELECT arrayMap(x -> stem('en', x), ['I', 'think', 'it', 'is', 'a', 'blessing', 'in', 'disguise']) as res;
```
Result:

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@ -8,10 +8,10 @@ toc_title: "Словарь"
``` sql
CREATE DICTIONARY [IF NOT EXISTS] [db.]dictionary_name [ON CLUSTER cluster]
(
key1 type1 [DEFAULT|EXPRESSION expr1] [HIERARCHICAL|INJECTIVE|IS_OBJECT_ID],
key2 type2 [DEFAULT|EXPRESSION expr2] [HIERARCHICAL|INJECTIVE|IS_OBJECT_ID],
attr1 type2 [DEFAULT|EXPRESSION expr3],
attr2 type2 [DEFAULT|EXPRESSION expr4]
key1 type1 [DEFAULT|EXPRESSION expr1] [IS_OBJECT_ID],
key2 type2 [DEFAULT|EXPRESSION expr2],
attr1 type2 [DEFAULT|EXPRESSION expr3] [HIERARCHICAL|INJECTIVE],
attr2 type2 [DEFAULT|EXPRESSION expr4] [HIERARCHICAL|INJECTIVE]
)
PRIMARY KEY key1, key2
SOURCE(SOURCE_NAME([param1 value1 ... paramN valueN]))