Vlad Horsun wrote:

> Yes, having all the select list's fields in sorted order is very good
> thing as it avoid needs to reread it from tables again. This is strong
> point no doubt.
>
> What i mean is that sorted runs contains whole records and during
> merge phase we must read it from disk and write back merged larger
> runs. Formally we need only keys to compare and merge.

Yes, but the whole requested record should be returned to the caller.

If they are not written after keys, how you will fast locate it in disk?


Adriano