This query option DELETE_STATS_IN_TRUNCATE can be used to delete or retain table statistics. The default value of this option is 1 or true which means table statistics will be deleted as part of truncate operation. However the default may not be an ideal solution in case of non-transactional tables when the table and column statistics for the table are also deleted by default. This can be an expensive operation especially when many truncate table commands are running concurrently. In cases where truncate operation is used to remove the existing data and then reload new data, it is likely that you will compute stats again as soon as the new data is reloaded. This would overwrite the existing statistics and hence the additional time spent by the truncate operation to delete column and table statistics becomes obsolete. To avoid this expensive operation and to improve performance, you can set this query option to false or 0. When set to false, a truncate operation will not delete the table and column statistics for the table.

Type:BOOLEAN; recognized values are 1 and 0, or true and false;

Default:TRUE (shown as 1 in output of SET statement).

Added in: Impala 4.0