8f3b4c4b7d
### What changes were proposed in this pull request?
This is a followup of https://github.com/apache/spark/pull/30648
ANALYZE TABLE and TABLES are essentially the same command, it's weird to put them in 2 different doc pages. This PR proposes to merge them into one doc page.
### Why are the changes needed?
simplify the doc
### Does this PR introduce _any_ user-facing change?
no
### How was this patch tested?
N/A
Closes #33781 from cloud-fan/doc.
Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
(cherry picked from commit 07d173a8b0)
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
184 lines
6.7 KiB
Markdown
184 lines
6.7 KiB
Markdown
---
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layout: global
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title: ANALYZE TABLE
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displayTitle: ANALYZE TABLE
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license: |
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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---
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### Description
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The `ANALYZE TABLE` statement collects statistics about one specific table or all the tables in one specified database,
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that are to be used by the query optimizer to find a better query execution plan.
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### Syntax
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```sql
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ANALYZE TABLE table_identifier [ partition_spec ]
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COMPUTE STATISTICS [ NOSCAN | FOR COLUMNS col [ , ... ] | FOR ALL COLUMNS ]
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```
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```sql
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ANALYZE TABLES [ { FROM | IN } database_name ] COMPUTE STATISTICS [ NOSCAN ]
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```
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### Parameters
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* **table_identifier**
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Specifies a table name, which may be optionally qualified with a database name.
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**Syntax:** `[ database_name. ] table_name`
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* **partition_spec**
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An optional parameter that specifies a comma separated list of key and value pairs
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for partitions. When specified, partition statistics is returned.
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**Syntax:** `PARTITION ( partition_col_name [ = partition_col_val ] [ , ... ] )`
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* **{ FROM `|` IN } database_name**
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Specifies the name of the database to be analyzed. Without a database name, `ANALYZE` collects all tables in the current database that the current user has permission to analyze.
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* **NOSCAN**
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Collects only the table's size in bytes (which does not require scanning the entire table).
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* **FOR COLUMNS col [ , ... ] `|` FOR ALL COLUMNS**
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Collects column statistics for each column specified, or alternatively for every column, as well as table statistics.
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If no analyze option is specified, both number of rows and size in bytes are collected.
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### Examples
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```sql
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CREATE DATABASE school_db;
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USE school_db;
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CREATE TABLE teachers (name STRING, teacher_id INT);
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INSERT INTO teachers VALUES ('Tom', 1), ('Jerry', 2);
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CREATE TABLE students (name STRING, student_id INT) PARTITIONED BY (student_id);
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INSERT INTO students VALUES ('Mark', 111111), ('John', 222222);
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ANALYZE TABLE students COMPUTE STATISTICS NOSCAN;
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DESC EXTENDED students;
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+--------------------+--------------------+-------+
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| col_name| data_type|comment|
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+--------------------+--------------------+-------+
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| name| string| null|
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| student_id| int| null|
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| ...| ...| ...|
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| Statistics| 864 bytes| |
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| ...| ...| ...|
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+--------------------+--------------------+-------+
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ANALYZE TABLE students COMPUTE STATISTICS;
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DESC EXTENDED students;
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+--------------------+--------------------+-------+
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| col_name| data_type|comment|
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+--------------------+--------------------+-------+
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| name| string| null|
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| student_id| int| null|
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| ...| ...| ...|
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| Statistics| 864 bytes, 2 rows| |
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| ...| ...| ...|
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+--------------------+--------------------+-------+
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ANALYZE TABLE students PARTITION (student_id = 111111) COMPUTE STATISTICS;
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DESC EXTENDED students PARTITION (student_id = 111111);
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+--------------------+--------------------+-------+
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| col_name| data_type|comment|
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+--------------------+--------------------+-------+
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| name| string| null|
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| student_id| int| null|
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| ...| ...| ...|
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|Partition Statistics| 432 bytes, 1 rows| |
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| ...| ...| ...|
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+--------------------+--------------------+-------+
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ANALYZE TABLE students COMPUTE STATISTICS FOR COLUMNS name;
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DESC EXTENDED students name;
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+--------------+----------+
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| info_name|info_value|
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+--------------+----------+
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| col_name| name|
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| data_type| string|
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| comment| NULL|
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| min| NULL|
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| max| NULL|
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| num_nulls| 0|
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|distinct_count| 2|
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| avg_col_len| 4|
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| max_col_len| 4|
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| histogram| NULL|
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+--------------+----------+
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ANALYZE TABLES IN school_db COMPUTE STATISTICS NOSCAN;
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DESC EXTENDED teachers;
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+--------------------+--------------------+-------+
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| col_name| data_type|comment|
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+--------------------+--------------------+-------+
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| name| string| null|
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| teacher_id| int| null|
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| ...| ...| ...|
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| Statistics| 1382 bytes| |
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| ...| ...| ...|
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+--------------------+--------------------+-------+
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DESC EXTENDED students;
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+--------------------+--------------------+-------+
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| col_name| data_type|comment|
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+--------------------+--------------------+-------+
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| name| string| null|
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| student_id| int| null|
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| ...| ...| ...|
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| Statistics| 864 bytes| |
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| ...| ...| ...|
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+--------------------+--------------------+-------+
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ANALYZE TABLES COMPUTE STATISTICS;
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DESC EXTENDED teachers;
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+--------------------+--------------------+-------+
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| col_name| data_type|comment|
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+--------------------+--------------------+-------+
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| name| string| null|
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| teacher_id| int| null|
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| ...| ...| ...|
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| Statistics| 1382 bytes, 2 rows| |
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| ...| ...| ...|
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+--------------------+--------------------+-------+
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DESC EXTENDED students;
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+--------------------+--------------------+-------+
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| col_name| data_type|comment|
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+--------------------+--------------------+-------+
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| name| string| null|
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| student_id| int| null|
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| ...| ...| ...|
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| Statistics| 864 bytes, 2 rows| |
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| ...| ...| ...|
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+--------------------+--------------------+-------+
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```
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