Login ProductsSalesSupportDownloadsAbout |
Home » Technical Support » DBISAM Technical Support » Support Forums » DBISAM General » View Thread |
Messages 1 to 4 of 4 total |
Lazy Change Detection clarification |
Thu, Feb 15 2007 3:17 PM | Permanent Link |
Michael Fullerton | 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? ___ Free Project Time Tracker for Delphi Developers http://www.cybermatrix.com/pcdelphi.html |
Fri, Feb 16 2007 3:08 PM | Permanent Link |
Tim Young [Elevate Software] Elevate Software, Inc. timyoung@elevatesoft.com | 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 |
Fri, Feb 16 2007 5:27 PM | Permanent Link |
Michael Fullerton | 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 |
Mon, Feb 19 2007 6:53 AM | Permanent Link |
Tim Young [Elevate Software] Elevate Software, Inc. timyoung@elevatesoft.com | 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 |
This web page was last updated on Friday, April 26, 2024 at 06:09 PM | Privacy PolicySite Map © 2024 Elevate Software, Inc. All Rights Reserved Questions or comments ? E-mail us at info@elevatesoft.com |