Creating statistics on unindexed columns can improve the performance of many
queries. Adding statistics for the minor columns of indexes and for unindexed columns that are
frequently used in search arguments can greatly improve the optimizer’s estimates.
- In the Administration Console view, select .
- Click the Name field of the table, then click the drop-down arrow and select
Properties.
- In the left pane, click Columns.
- Click the Name field of the column, then click the drop-down arrow and select
Update Statistics.
- (Optional) On the Data Partitions screen of the Update Statistics wizard,
select Specify a data partition, if
applicable, and indicate any data partitions. update
statistics runs on all partitions if you do not specify one.
- On the Hashing screen, select:
- The type of hashing:
- Partial hashing – for columns that have 65536 or fewer unique
values.
- With hashing – for columns that have more than 65536
unique values.
- No hashing.
- A value for max resource granularity (which indicates the
maximum percentage of the system’s resources a query can use), if
applicable.
- On the Histogram Tuning screen, set the histogram tuning factor. The size of
the histogram is established by multiplying the number of steps with the value for
histogram tuning factor.
- On the Sampling screen, specify whether to set sampling, and to what percentage.
- On the Step Number screen, indicate whether to set the number of histogram steps. If applicable, enter the number.
- On the Consumers screen, set the number of consumer processes to be used in
parallel processing. The controls are enabled if the value for max parallel degree is 3 or greater.
- On the Datachange Threshold screen, indicate whether to run update statistics when it reaches a
data change threshold, and if so, the value of the threshold.
- On the Summary screen, verify your selections.
- Click Finish.