Databases Reference
In-Depth Information
We can see that by executing the same
INSERT
statement with four indexes in place, the
executing time has increased from less than 1 second to more than 6 seconds. There is a
considerable dip in performance, due to the overhead involved in updating the indexes when
inserting records.
In step 7 we empty the table and drop the indexes, returning to the initial state with the
MY_CUSTOMERS
table empty and without any index.
In step 8 we add a field
MAX_CREDIT
to the
MY_CUSTOMERS
table. We define a trigger, which
fires before the insert or update on the
MY_CUSTOMERS
table to set the
MAX_CREDIT
field
according to a business rule in step 9.
In step 10 we insert records in the
MY_CUSTOMERS
table, obtaining the following results:
