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SHOW STATS_HISTOGRAMS

This statement shows the histogram information collected by the ANALYZE statement as part of database statistics.

Currently, the SHOW STATS_HISTOGRAMS statement returns the following columns:

Column nameDescription
Db_nameDatabase name
Table_nameThe table name
Partition_nameThe partition name
Column_nameThe column name (when is_index is 0) or the index name (when is_index is 1)
Is_indexWhether it is an index column or not
Update_timeThe update time
Distinct_countThe distinct count
Null_countNULL count
Avg_col_sizeThe average col size
CorrelationPearson correlation coefficient between this column and the integer primary key column, indicating the degree of association between the two columns
Load_statusLoad status, such as allEvicted and allLoaded
Total_mem_usageThe total memory usage
Hist_mem_usageThe historical memory usage
Topn_mem_usageThe TopN memory usage
Cms_mem_usageThe CMS memory usage

Synopsis

ShowStatsHistogramsStmt
SHOWSTATS_HISTOGRAMSShowLikeOrWhere
ShowLikeOrWhere
LIKESimpleExprWHEREExpression

Examples

SHOW STATS_HISTOGRAMS;
+---------+------------+----------------+-------------+----------+---------------------+----------------+------------+--------------+-------------+ | Db_name | Table_name | Partition_name | Column_name | Is_index | Update_time | Distinct_count | Null_count | Avg_col_size | Correlation | +---------+------------+----------------+-------------+----------+---------------------+----------------+------------+--------------+-------------+ | test | t | | a | 0 | 2020-05-25 19:20:00 | 7 | 0 | 1 | 1 | | test | t2 | | a | 0 | 2020-05-25 19:20:01 | 6 | 0 | 8 | 0 | | test | t2 | | b | 0 | 2020-05-25 19:20:01 | 6 | 0 | 1.67 | 1 | +---------+------------+----------------+-------------+----------+---------------------+----------------+------------+--------------+-------------+ 3 rows in set (0.00 sec)
SHOW STATS_HISTOGRAMS WHERE table_name = 't2';
+---------+------------+----------------+-------------+----------+---------------------+----------------+------------+--------------+-------------+ | Db_name | Table_name | Partition_name | Column_name | Is_index | Update_time | Distinct_count | Null_count | Avg_col_size | Correlation | +---------+------------+----------------+-------------+----------+---------------------+----------------+------------+--------------+-------------+ | test | t2 | | b | 0 | 2020-05-25 19:20:01 | 6 | 0 | 1.67 | 1 | | test | t2 | | a | 0 | 2020-05-25 19:20:01 | 6 | 0 | 8 | 0 | +---------+------------+----------------+-------------+----------+---------------------+----------------+------------+--------------+-------------+ 2 rows in set (0.00 sec)

MySQL compatibility

This statement is a TiDB extension to MySQL syntax.

See also

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