ANALYZE TABLE

Description

The ANALYZE TABLE statement collects statistics about one specific table or all the tables in one specified database, that are to be used by the query optimizer to find a better query execution plan. These statistics are stored in the catalog.

Syntax

ANALYZE TABLE table_identifier [ partition_spec ]
    COMPUTE STATISTICS [ NOSCAN | FOR COLUMNS col [ , ... ] | FOR ALL COLUMNS ]
ANALYZE TABLES [ { FROM | IN } database_name ] COMPUTE STATISTICS [ NOSCAN ]

Parameters

If no analyze option is specified, both number of rows and size in bytes are collected.

Examples

CREATE DATABASE school_db;
USE school_db;

CREATE TABLE teachers (name STRING, teacher_id INT);
INSERT INTO teachers VALUES ('Tom', 1), ('Jerry', 2);

CREATE TABLE students (name STRING, student_id INT) PARTITIONED BY (student_id);
INSERT INTO students VALUES ('Mark', 111111), ('John', 222222);

ANALYZE TABLE students COMPUTE STATISTICS NOSCAN;

DESC EXTENDED students;
+--------------------+--------------------+-------+
|            col_name|           data_type|comment|
+--------------------+--------------------+-------+
|                name|              string|   null|
|          student_id|                 int|   null|
|                 ...|                 ...|    ...|
|          Statistics|           864 bytes|       |
|                 ...|                 ...|    ...|
+--------------------+--------------------+-------+

ANALYZE TABLE students COMPUTE STATISTICS;

DESC EXTENDED students;
+--------------------+--------------------+-------+
|            col_name|           data_type|comment|
+--------------------+--------------------+-------+
|                name|              string|   null|
|          student_id|                 int|   null|
|                 ...|                 ...|    ...|
|          Statistics|   864 bytes, 2 rows|       |
|                 ...|                 ...|    ...|
+--------------------+--------------------+-------+

ANALYZE TABLE students PARTITION (student_id = 111111) COMPUTE STATISTICS;

DESC EXTENDED students PARTITION (student_id = 111111);
+--------------------+--------------------+-------+
|            col_name|           data_type|comment|
+--------------------+--------------------+-------+
|                name|              string|   null|
|          student_id|                 int|   null|
|                 ...|                 ...|    ...|
|Partition Statistics|   432 bytes, 1 rows|       |
|                 ...|                 ...|    ...|
+--------------------+--------------------+-------+

ANALYZE TABLE students COMPUTE STATISTICS FOR COLUMNS name;

DESC EXTENDED students name;
+--------------+----------+
|     info_name|info_value|
+--------------+----------+
|      col_name|      name|
|     data_type|    string|
|       comment|      NULL|
|           min|      NULL|
|           max|      NULL|
|     num_nulls|         0|
|distinct_count|         2|
|   avg_col_len|         4|
|   max_col_len|         4|
|     histogram|      NULL|
+--------------+----------+

ANALYZE TABLES IN school_db COMPUTE STATISTICS NOSCAN;

DESC EXTENDED teachers;
+--------------------+--------------------+-------+
|            col_name|           data_type|comment|
+--------------------+--------------------+-------+
|                name|              string|   null|
|          teacher_id|                 int|   null|
|                 ...|                 ...|    ...|
|          Statistics|          1382 bytes|       |
|                 ...|                 ...|    ...|
+--------------------+--------------------+-------+

DESC EXTENDED students;
+--------------------+--------------------+-------+
|            col_name|           data_type|comment|
+--------------------+--------------------+-------+
|                name|              string|   null|
|          student_id|                 int|   null|
|                 ...|                 ...|    ...|
|          Statistics|           864 bytes|       |
|                 ...|                 ...|    ...|
+--------------------+--------------------+-------+

ANALYZE TABLES COMPUTE STATISTICS;

DESC EXTENDED teachers;
+--------------------+--------------------+-------+
|            col_name|           data_type|comment|
+--------------------+--------------------+-------+
|                name|              string|   null|
|          teacher_id|                 int|   null|
|                 ...|                 ...|    ...|
|          Statistics|  1382 bytes, 2 rows|       |
|                 ...|                 ...|    ...|
+--------------------+--------------------+-------+

DESC EXTENDED students;
+--------------------+--------------------+-------+
|            col_name|           data_type|comment|
+--------------------+--------------------+-------+
|                name|              string|   null|
|          student_id|                 int|   null|
|                 ...|                 ...|    ...|
|          Statistics|   864 bytes, 2 rows|       |
|                 ...|                 ...|    ...|
+--------------------+--------------------+-------+