collect_statistics_on_dml_updates option [database]
Controls the gathering of statistics during the execution of data-altering DML statements such as INSERT,
DELETE, and UPDATE.
Allowed values
On, Off
Default
On
Remarks
The server updates statistics during normal statement execution and uses the gathered statistics to self-tune
the column statistics. Set the collect_statistics_on_dml_updates option to Off to disable the updating of
statistics during the execution of data-altering DML statements such as INSERT, DELETE, and UPDATE.
Under normal circumstances, it should not be necessary to turn this option off. However, in environments
where significantly large amounts of data are frequently changing, setting this option to Off may improve
performance—assuming update_statistics is also set to On.
The difference between the collect_statistics_on_dml_updates option and the update_statistics option is that
the update_statistics option compares the actual number of rows that satisfy a predicate with the number of
rows that are estimated to satisfy the predicate, and then updates the estimates accordingly. The
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collect_statistics_on_dml_updates option modifies the column statistics based on the values of the specific
rows that are inserted, updated, or deleted.
See also
♦ “ update_statistics option [database]” on page 470
♦ “Updating column statistics” [SQL Anywhere Server - SQL Usage] Introduction to database options

вообще-то решение это годится исключительно как костыль. Дело в том, что вообще вся работа оптимизатора строится на статистиках. И если у вас что-то идет не так, то надо смотреть, как изменился план выполнения запроса. Я бы статистику вообще не трогал никогда. Если не учитывать статистику, то имеет смысл остановиться на технологиях уровня DBF.