--- In Firebird-Architect@yahoogroups.com, "Dmitry Yemanov"
<dimitr@u...> wrote:

> Paul,
>

Dmitry,

Thank you. The pipelined/tree-like structure of RSB's had escaped me
so far and I was already wondering how operations were combined. By
now I have set my mind on bringing clarity to this bit of engine code
and I will try to make it stand out better that RSE's are a pipeline
or operation tree, with a certain 'stacking order'.

Starting later today I'll be traveling for a week, so no quick
responses - but please keep the suggestions and explanations coming.

Paul

> From the higher levels POV, RSB is a cursor. It can be opened,

fetched and

> closed. More precisely (from the implementation POV), RSB is a
> transformation from one data stream to another. Lowest-level RSBs
> (rsb_sequential, rsb_indexed, rsb_navigate) are plain access types.
> rsb_boolean applies a filter to the input stream, rsb_skip removes

first N

> rows from a stream via N dummy fetches, rsb_join merges two streams

into one

> using the nested loops algorithm and so on. They are linked in a

chain by

> the optimizer to produce the wanted result. Their common parts are:

(a) they

> share the same public interface and (b) they have K ( 0 <= K <

inf ) input

> RSBs.
>
> Hope Jim will explain it better ;-)
>
>
> Dmitry