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Merge pull request #23457 from sevirov/sevirov-DOCSUP-8737-edit_and_translate_to_russian_explain
DOCSUP-8737: Edit and translate to Russian (EXPLAIN)
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@ -5,7 +5,7 @@ toc_title: EXPLAIN
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# EXPLAIN Statement {#explain}
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# EXPLAIN Statement {#explain}
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Show the execution plan of a statement.
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Shows the execution plan of a statement.
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Syntax:
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Syntax:
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@ -65,7 +65,7 @@ SelectWithUnionQuery (children 1)
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### EXPLAIN SYNTAX {#explain-syntax}
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### EXPLAIN SYNTAX {#explain-syntax}
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Return query after syntax optimizations.
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Returns query after syntax optimizations.
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Example:
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Example:
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@ -88,15 +88,16 @@ FROM
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) AS `--.s`
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) AS `--.s`
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CROSS JOIN system.numbers AS c
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CROSS JOIN system.numbers AS c
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```
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```
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### EXPLAIN PLAN {#explain-plan}
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### EXPLAIN PLAN {#explain-plan}
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Dump query plan steps.
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Dump query plan steps.
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Settings:
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Settings:
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- `header` — Print output header for step. Default: 0.
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- `header` — Prints output header for step. Default: 0.
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- `description` — Print step description. Default: 1.
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- `description` — Prints step description. Default: 1.
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- `actions` — Print detailed information about step actions. Default: 0.
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- `actions` — Prints detailed information about step actions. Default: 0.
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Example:
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Example:
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@ -115,15 +116,16 @@ Union
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```
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```
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!!! note "Note"
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!!! note "Note"
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Step and query cost estimation is not supported.
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Step and query cost estimation is not supported.
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### EXPLAIN PIPELINE {#explain-pipeline}
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### EXPLAIN PIPELINE {#explain-pipeline}
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Settings:
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Settings:
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- `header` — Print header for each output port. Default: 0.
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- `header` — Prints header for each output port. Default: 0.
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- `graph` — Use DOT graph description language. Default: 0.
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- `graph` — Prints a graph described in the [DOT](https://en.wikipedia.org/wiki/DOT_(graph_description_language)) graph description language. Default: 0.
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- `compact` — Print graph in compact mode if graph is enabled. Default: 1.
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- `compact` — Prints graph in compact mode if `graph` setting is enabled. Default: 1.
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- `indexes` — Shows used indexes, the number of filtered parts, and granules for every index applied. Default: 0. Supported for [MergeTree](../../engines/table-engines/mergetree-family/mergetree.md) tables.
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Example:
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Example:
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152
docs/ru/sql-reference/statements/explain.md
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152
docs/ru/sql-reference/statements/explain.md
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@ -0,0 +1,152 @@
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---
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toc_priority: 39
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toc_title: EXPLAIN
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---
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# EXPLAIN {#explain}
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Выводит план выполнения запроса.
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Синтаксис:
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```sql
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EXPLAIN [AST | SYNTAX | PLAN | PIPELINE] [setting = value, ...] SELECT ... [FORMAT ...]
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```
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Пример:
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```sql
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EXPLAIN SELECT sum(number) FROM numbers(10) UNION ALL SELECT sum(number) FROM numbers(10) ORDER BY sum(number) ASC FORMAT TSV;
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```
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```sql
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Union
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Expression (Projection)
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Expression (Before ORDER BY and SELECT)
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Aggregating
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Expression (Before GROUP BY)
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SettingQuotaAndLimits (Set limits and quota after reading from storage)
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ReadFromStorage (SystemNumbers)
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Expression (Projection)
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MergingSorted (Merge sorted streams for ORDER BY)
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MergeSorting (Merge sorted blocks for ORDER BY)
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PartialSorting (Sort each block for ORDER BY)
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Expression (Before ORDER BY and SELECT)
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Aggregating
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Expression (Before GROUP BY)
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SettingQuotaAndLimits (Set limits and quota after reading from storage)
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ReadFromStorage (SystemNumbers)
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```
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## Типы EXPLAIN {#explain-types}
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- `AST` — абстрактное синтаксическое дерево.
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- `SYNTAX` — текст запроса после оптимизации на уровне AST.
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- `PLAN` — план выполнения запроса.
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- `PIPELINE` — конвейер выполнения запроса.
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### EXPLAIN AST {#explain-ast}
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Дамп AST запроса.
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Пример:
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```sql
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EXPLAIN AST SELECT 1;
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```
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```sql
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SelectWithUnionQuery (children 1)
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ExpressionList (children 1)
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SelectQuery (children 1)
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ExpressionList (children 1)
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Literal UInt64_1
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```
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### EXPLAIN SYNTAX {#explain-syntax}
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Возвращает текст запроса после применения синтаксических оптимизаций.
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Пример:
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```sql
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EXPLAIN SYNTAX SELECT * FROM system.numbers AS a, system.numbers AS b, system.numbers AS c;
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```
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```sql
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SELECT
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`--a.number` AS `a.number`,
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`--b.number` AS `b.number`,
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number AS `c.number`
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FROM
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(
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SELECT
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number AS `--a.number`,
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b.number AS `--b.number`
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FROM system.numbers AS a
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CROSS JOIN system.numbers AS b
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) AS `--.s`
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CROSS JOIN system.numbers AS c
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```
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### EXPLAIN PLAN {#explain-plan}
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Дамп шагов выполнения запроса.
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Настройки:
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- `header` — выводит выходной заголовок для шага. По умолчанию: 0.
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- `description` — выводит описание шага. По умолчанию: 1.
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- `actions` — выводит подробную информацию о действиях, выполняемых на данном шаге. По умолчанию: 0.
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Пример:
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```sql
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EXPLAIN SELECT sum(number) FROM numbers(10) GROUP BY number % 4;
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```
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```sql
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Union
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Expression (Projection)
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Expression (Before ORDER BY and SELECT)
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Aggregating
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Expression (Before GROUP BY)
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SettingQuotaAndLimits (Set limits and quota after reading from storage)
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ReadFromStorage (SystemNumbers)
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```
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!!! note "Примечание"
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Оценка стоимости выполнения шага и запроса не поддерживается.
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### EXPLAIN PIPELINE {#explain-pipeline}
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Настройки:
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- `header` — выводит заголовок для каждого выходного порта. По умолчанию: 0.
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- `graph` — выводит граф, описанный на языке [DOT](https://ru.wikipedia.org/wiki/DOT_(язык)). По умолчанию: 0.
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- `compact` — выводит граф в компактном режиме, если включена настройка `graph`. По умолчанию: 1.
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- `indexes` — показывает используемые индексы, количество отфильтрованных кусков и гранул для каждого примененного индекса. По умолчанию: 0. Поддерживается для таблиц семейства [MergeTree](../../engines/table-engines/mergetree-family/mergetree.md).
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Пример:
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```sql
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EXPLAIN PIPELINE SELECT sum(number) FROM numbers_mt(100000) GROUP BY number % 4;
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```
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```sql
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(Union)
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(Expression)
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ExpressionTransform
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(Expression)
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ExpressionTransform
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(Aggregating)
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Resize 2 → 1
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AggregatingTransform × 2
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(Expression)
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ExpressionTransform × 2
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(SettingQuotaAndLimits)
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(ReadFromStorage)
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NumbersMt × 2 0 → 1
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```
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[Оригинальная статья](https://clickhouse.tech/docs/ru/sql-reference/statements/explain/) <!--hide-->
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