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Thread Live versus canned result sets in TDBGrid
Tue, Jun 24 2008 6:59 PMPermanent Link

Oliver Bock
If operating in client/server mode over an ADSL connection, would I be
better off attaching a TDBGrid to a live result set or a canned result
set, if the data set is large?  As I understand things:

- A canned result set must be fetched in its entirety before any data
  can be retrieved.  Therefore the TDBGrid will be slow to display
  at first, but fast to scroll.

- TDBGrid will be able to fetch only the rows that are visible needs
  from a live.  Therefore the grid will show quickly, but I guess that
  scrolling will be slow because it requires a round trip back to the
  server.

Have I got this right?


  Oliver
Tue, Jun 24 2008 7:24 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Oliver,

<< If operating in client/server mode over an ADSL connection, would I be
better off attaching a TDBGrid to a live result set or a canned result set,
if the data set is large? >>

It doesn't matter - both will fetch the same number of rows, i.e. only the
rows required to fill the grid.  And it will do so in one chunk in order to
optimize the fetch.  This all happens automatically.

--
Tim Young
Elevate Software
www.elevatesoft.com

Tue, Jun 24 2008 7:57 PMPermanent Link

Oliver Bock
Tim Young [Elevate Software] wrote:
> << If operating in client/server mode over an ADSL connection, would I be
> better off attaching a TDBGrid to a live result set or a canned result set,
> if the data set is large? >>
>
> It doesn't matter - both will fetch the same number of rows, i.e. only the
> rows required to fill the grid.  And it will do so in one chunk in order to
> optimize the fetch.  This all happens automatically.

Thanks Tim.  So the canned set will be calculated in its entirety on the
server before any rows are returned to the client, but then only those
rows requested will be sent over the connection.

For a live result set, there is no need to build the result set, and
only those rows required will be sent over the connection.
Tue, Jun 24 2008 8:41 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Oliver,

<< Thanks Tim.  So the canned set will be calculated in its entirety on the
serrver before any rows are returned to the client, but then only those rows
requested will be sent over the connection.

For a live result set, there is no need to build the result set, and only
those rows required will be sent over the connection. >>

Yep - 100% correct.

--
Tim Young
Elevate Software
www.elevatesoft.com

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