Collects and aggregates data samples and storage information for a range of partitions in the specified table. Vertica writes the collected statistics to the database catalog.
If you specify multiple partitions, they must be continuous. Different collections can overlap—for example, given partition keys of 1 through 99, successive calls to
ANALYZE_STATISTICS_PARTITION can collect statistics for partitions 1-60 and 50-99. Similarly, one collection of statistics can be a subset of an earlier collection. In all cases, Vertica stores only the most recent statistics for each partition range. Thus, given the previous example, Vertica uses only statistics from the second collection for partition keys 50 through 60.
When you query a partitioned table, the Vertica optimizer checks whether the partitions required by this query have recently been analyzed. If so, the optimizer retrieves those statistics and uses them to facilitate query planning. Otherwise, it uses table-level statistics, if available; if none, the optimizer assumes uniform distribution of data values and equal storage usage for all projections.
You can cancel statistics collection with CTRL+C or by calling
ANALYZE_STATISTICS_PARTITION ('[[database.]schema.]table', 'min‑range‑value','max‑range‑value' [, 'column[,…]'] [, percent ] )
If an error occurs, refer to
vertica.log for details.
Specifies a schema, by default
If you specify a database, it must be the current database.
The table on which to collect data.
The minimum and maximum value of partition keys to analyze, where min‑range‑value must be ≤ max‑range‑value. To analyze one partition, min‑range‑value and max‑range‑value must be equal.
The name of a column in table, typically a predicate column. You can specify multiple comma-delimited columns. Vertica narrows the scope of the data collection to the specified columns.
A float value between 0 and 100 that specifies what percentage of data to read from disk (not the amount of data to analyze). If you omit this argument, Vertica sets the percentage to 10.
Analyzing more than 10 percent disk space takes proportionally longer to process, but produces a higher level of sampling accuracy.
- Schema: USAGE
- Table: One of INSERT, DELETE, or UPDATE
Requirements and Restrictions
- The table must be partitioned and must not contain unpartitioned data.
- The table's partition expression can specify only one column.
- Vertica collects no statistics from the following projections:
- Live aggregate and Top-K projections
- Projections that are defined to include an SQL function within an expression