The SAS
providers support the following ADO and OLE DB properties that affect
the performance of your application.
Property Names and Supported Providers
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Supported in ADO by
all providers
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Supported by all providers
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Supported by the IOM
provider
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Supported by the IOM
provider
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These
properties determine how much data is retrieved and cached at different
architectural levels. They will affect performance for better or for
worse, depending on how you use them in your application. For example,
significant performance improvement occurs when each accessed row
is relatively close to the previously accessed row. However, if your
application randomly accesses rows or only accesses a few rows, then
increased data caching might degrade performance. To optimize performance
in this case, you can take the following two steps:
-
If you have enough RAM to hold
the entire data set in memory and your application accesses most of
the rows in the data set, then increase the amount of data cached
to match the amount of data in the data set.
-
If you do not have enough RAM or
your application needs to access only a few rows in the data set,
then lower the amount of cached data to minimize the transfer of unused
rows.
Tip
When you develop
your application, you should test different values for these properties
to determine which values will result in the best performance for
your target environment.
Note: The IOM provider
also supports optimized accessors as described in the
OLE
DB Programmer's Reference and Data Access SDK. This feature
enables OLE DB consumers to specify which columns should be included
in the provider's cache.
Tip
The sample
code in this chapter assumes that an ADO Connection object is open.
For more information, see Basic Connection Recipes.