Note
This view is available starting with V3.2.1.
Purpose
This view displays the column statistics and histogram information of tables owned by the current user.
Applicability
This view is available only in Oracle mode of OceanBase Database.
Columns
| Column | Type | Nullable? | Description |
|---|---|---|---|
| TABLE_NAME | VARCHAR2(128) | NO | The name of the table to which the column belongs. |
| COLUMN_NAME | VARCHAR2(128) | NO | The name of the column. |
| NUM_DISTINCT | NUMBER | YES | The number of distinct values in the column. |
| LOW_VALUE | VARCHAR2(128) | YES | The minimum value in the column. |
| HIGH_VALUE | VARCHAR2(128) | YES | The maximum value in the column. |
| DENSITY | NUMBER | YES | The density of the column. |
| NUM_NULLS | NUMBER | YES | The number of NULL values in the column. |
| NUM_BUCKETS | NUMBER | YES | The number of buckets in the histogram of the column. |
| LAST_ANALYZED | DATE | YES | The time when the last analysis was performed. |
| SAMPLE_SIZE | NUMBER | YES | The sample size used during the analysis. |
| GLOBAL_STATS | VARCHAR2(3) | YES | YES: Indicates that the statistics were collected directly or incrementally maintained.NO: Other cases. |
| USER_STATS | VARCHAR2(3) | YES | Indicates whether the partition statistics are user-defined. |
| NOTES | VARCHAR2(80) | YES | Records some additional attributes. |
| AVG_COL_LEN | NUMBER | YES | The average length of the column. |
| HISTOGRAM | VARCHAR2(15) | YES | The type of the histogram. |
| SCOPE | VARCHAR2(7) | YES | The scope of the statistics. |
Sample query
Query the column statistics and histogram information of the T_SUBPART table owned by the current user.
obclient [SYS]> SELECT TABLE_NAME, COLUMN_NAME, NUM_DISTINCT, LOW_VALUE, HIGH_VALUE, DENSITY, NUM_NULLS, NUM_BUCKETS, SAMPLE_SIZE, AVG_COL_LEN, HISTOGRAM FROM SYS.USER_TAB_COL_STATISTICS WHERE TABLE_NAME ='T_SUBPART' ORDER BY 1, 2, 3;
The query result is as follows:
+------------+-------------+--------------+-----------+------------+------------------------+-----------+-------------+-------------+-------------+-----------+
| TABLE_NAME | COLUMN_NAME | NUM_DISTINCT | LOW_VALUE | HIGH_VALUE | DENSITY | NUM_NULLS | NUM_BUCKETS | SAMPLE_SIZE | AVG_COL_LEN | HISTOGRAM |
+------------+-------------+--------------+-----------+------------+------------------------+-----------+-------------+-------------+-------------+-----------+
| T_SUBPART | C1 | 10191 | 0 | 9999 | .000098125797272102829 | 0 | 5 | 10000 | 20 | HYBRID |
| T_SUBPART | C2 | 1031 | 0 | 999 | .00096993210475266732 | 0 | 5 | 10000 | 20 | HYBRID |
| T_SUBPART | C3 | 1973 | 0 | 1999 | .00050684237202230106 | 0 | 5 | 10000 | 20 | HYBRID |
+------------+-------------+--------------+-----------+------------+------------------------+-----------+-------------+-------------+-------------+-----------+
3 rows in set
References
To view the statistics of tables accessible to the current user, see ALL_TAB_COL_STATISTICS.
To view the statistics of all tables in the current tenant, see DBA_TAB_COL_STATISTICS.
To query column-level statistics, see the following views:
To query column-level statistics at the partition level, see the following views:
To query column-level statistics at the subpartition level, see the following views:
To query histogram statistics at the table level, see the following views:
To query histogram statistics at the partition level, see the following views:
To query histogram statistics at the subpartition level, see the following views:
To query index statistics, see the following views:
For information about how to collect statistics, see the following topics: