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< th colspan = "3" align = "center" > DbMpoolFile::set_priority()< / th >
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< h2 class = "title" style = "clear: both" > < a id = "mempset_priority" > < / a > DbMpoolFile::set_priority()< / h2 >
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< pre class = "programlisting" > #include < db_cxx.h>
int
DbMpoolFile::set_priority(DB_CACHE_PRIORITY priority); < / pre >
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Set the cache priority for pages referenced by the
< a class = "link" href = "memp.html" title = "Chapter > DbMpoolFile< / a > handle.
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The priority of a page biases the replacement algorithm to be more or
less likely to discard a page when space is needed in the cache.
The bias is temporary, and pages will eventually be discarded if they
are not referenced again. The < code class = "methodname" > DbMpoolFile::set_priority()< / code > method is
only advisory, and does not guarantee pages will be treated in a
specific way.
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To set the priority for the pages belonging to a particular database,
call the < code class = "methodname" > DbMpoolFile::set_priority()< / code > method using the
< a class = "link" href = "memp.html" title = "Chapter > DbMpoolFile< / a > handle
returned by the < a class = "xref" href = "dbget_mpf.html" title = "Db::get_mpf()" > Db::get_mpf()< / a > method.
< / p >
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The < code class = "methodname" > DbMpoolFile::set_priority()< / code > method configures a file in the
cache, not only operations performed using the specified
< a class = "link" href = "memp.html" title = "Chapter > DbMpoolFile< / a > handle.
< / p >
< p >
The < code class = "methodname" > DbMpoolFile::set_priority()< / code > method may be called at any time
during the life of the application.
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< p >
The < code class = "methodname" > DbMpoolFile::set_priority()< / code > < span >
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method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
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< h4 class = "title" > < a id = "id3632140" > < / a > priority< / h4 >
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The < span class = "bold" > < strong > priority< / strong > < / span > parameter must be set to
one of the following values:
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< code class = "literal" > DB_PRIORITY_VERY_LOW< / code >
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The lowest priority: pages are the most likely to be discarded.
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< code class = "literal" > DB_PRIORITY_LOW< / code >
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The next lowest priority.
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< code class = "literal" > DB_PRIORITY_DEFAULT< / code >
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The default priority.
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< code class = "literal" > DB_PRIORITY_HIGH< / code >
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The next highest priority.
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< code class = "literal" > DB_PRIORITY_VERY_HIGH< / code >
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The highest priority: pages are the least likely to be discarded.
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< a class = "xref" href = "memp.html#memplist" title = "Memory Pools and Related Methods" > Memory Pools and Related Methods< / a >
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