>>But why not other limits?

>>for example:
>> select .... limit time 5000 ms

> "ms" has nothing to do with SQL.

The engine know concept millisecond ;)

>> select .... limit read 1000 datapage

> datapages have nothing to do with SQL.

The engine know concept datapage/indexpage etc. ;)

>>select .... limit time 5000 ms
>> break select if time of composition too long
>> (for example not indexed join)
>
>
> And then what? What should the engine return then?

Exception against run a lot of hour ;)

eMeL