After dropping table and loading table, using update statistics table and update statistics separately; why the execute time of the latter is shorter than the former’s? Are the disposal methods in the DBMaker different between the two? And besides the data of the systablespace, what other systamcatalog will be updated when executing update statistics?
The disposal methods between the update statistics and update statistics table are different. Because that the update statistics will update all the table’s column, index and so on. So in order to save the resource, it is only update the statistics when there have accumulated certain amount data. As a result, the user finds that the update statistics takes less time.
User can use the following statement to force the DBMaker to update all the statistics:
update statistics sample=100
The update statistics statement will update table,column,index. So all systables that include them will be updated.