Topic: New index - productivity select vs insert
As it is known, at creation of a new index it is required to weigh productivity of readings vs updates. But something I anywhere did not meet specific approaches actually as it to do.
Therefore for an example took one table and typical with and supporting this an index.
That does this index - it replaces tables on seek.
The table of small, 150 records. In the presence of an index, there will be a following statistics:
select->>> Table ' MyTable '. Scan count 2, logical reads 15, physical reads 0... insert->>> Table ' MyTable '. Scan count 0, logical reads 4, physical reads 0...
Without an index:
select->>> Table ' MyTable '. Scan count 2, logical reads 18, physical reads 0... insert->>> Table ' MyTable '. Scan count 0, logical reads 2, physical reads 0...
I.e. we have such situation that on 3 logical reads it is less, and - on 2 it is more. I.e. from an index in 1 logical read as a whole.
- I correctly understand, what when the table becomes big, hundred thousand records - that the difference (because of in ) becomes where , after all will be all table, and index logical reads at increase slightly? Adjusted for an amount vs
- So-whether it is necessary to estimate usefulness of indexes generally?