According to the help, with lazy change detection, changes are checked
only if "DBISAM cannot find the desired data locally in it's cache
buffers". When does that apply? When a table is empty? When Findkey
fails?

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Michael,

<< According to the help, with lazy change detection, changes are checked
only if "DBISAM cannot find the desired data locally in it's cache buffers".
When does that apply? When a table is empty? When Findkey fails? >>

Any time DBISAM accesses the table data.

--
Tim Young
Elevate Software
www.elevatesoft.com

On Fri, 16 Feb 2007 15:08:15 -0500, "Tim Young [Elevate Software]"
<timyoung@elevatesoft.com> wrote:

><< According to the help, with lazy change detection, changes are checked
>only if "DBISAM cannot find the desired data locally in it's cache buffers".
>When does that apply? When a table is empty? When Findkey fails? >>
>
>Any time DBISAM accesses the table data.

What I mean is when would DBISAM not be able to find the desired data
locally in it's cache buffers? I guess that would mean only when it
needs a record that would be beyond the beginning or end of the cache.
Suppose another person adds a new record. You do a FindKey on that
key. Since the key is not in the cache would the cache be refreshed or
would FindKey just fail?

___
Free Project Time Tracker for Delphi Developers
http://www.cybermatrix.com/pcdelphi.html

Michael,

<< What I mean is when would DBISAM not be able to find the desired data
locally in it's cache buffers? >>

Such an event is possible at any time. The cache is limited in size, so it
can only contain the most recently referenced data.  Performing a search,
first, last, next, prior, etc. could all possibly require a read, and
subsequently, change detection.

<< Suppose another person adds a new record. You do a FindKey on that key.
Since the key is not in the cache would the cache be refreshed or would
FindKey just fail? >>

DBISAM would get the data from disk and the cache would be refreshed if the
data has changed in the table since the last read.

--
Tim Young
Elevate Software
www.elevatesoft.com