SVV_INTERLEAVED_COLUMNS
Use the SVV_INTERLEAVED_COLUMNS view to help determine whether a table that uses interleaved sort keys should be reindexed using VACUUM REINDEX. For more information about how to determine how often to run VACUUM and when to run a VACUUM REINDEX, see Minimizing vacuum times.
SVV_INTERLEAVED_COLUMNS is visible only to superusers. For more information, see Visibility of data in system tables and views.
Table columns
| Column name | Data type | Description |
|---|---|---|
| tbl | integer | Table ID. |
| col | integer | Zero-based index for the column. |
| interleaved_skew | numeric(19,2) | Ratio that indicates of the amount of skew present in the interleaved sort key columns for a table. A value of 1.00 indicates no skew, and larger values indicate more skew. Tables with a large skew should be reindexed with the VACUUM REINDEX command. |
| last_reindex | timestamp | Time when the last VACUUM REINDEX was run for the specified table. This value is NULL if a table has never been reindexed or if the underlying system log table, STL_VACUUM, has been rotated since the last reindex. |
Sample queries
To identify tables that might need to be reindexed, run the following query.
select tbl as tbl_id, stv_tbl_perm.name as table_name, col, interleaved_skew, last_reindex from svv_interleaved_columns, stv_tbl_perm where svv_interleaved_columns.tbl = stv_tbl_perm.id and interleaved_skew is not null; tbl_id | table_name | col | interleaved_skew | last_reindex --------+------------+-----+------------------+-------------------- 100068 | lineorder | 0 | 3.65 | 2015-04-22 22:05:45 100068 | lineorder | 1 | 2.65 | 2015-04-22 22:05:45 100072 | customer | 0 | 1.65 | 2015-04-22 22:05:45 100072 | lineorder | 1 | 1.00 | 2015-04-22 22:05:45 (4 rows)
