| java.lang.Object
 org.apache.derby.impl.sql.execute.GenericScanQualifier
| GenericScanQualifier | | public class GenericScanQualifier implements ScanQualifier(Code) | | This is the implementation for ScanQualifier. It is used for system and user
scans.
version:
0.1
author:
Jerry Brenner |
| GenericScanQualifier | | public GenericScanQualifier()(Code) | | |
| clearOrderableCache | | public void clearOrderableCache()(Code) | | Clear the DataValueDescriptor cache, if one exists.
(The DataValueDescriptor can be 1 of 3 types:
o VARIANT - cannot be cached as its value can
vary within a scan
o SCAN_INVARIANT - can be cached within a scan as its
value will not change within a scan
o QUERY_INVARIANT- can be cached across the life of the query
as its value will never change
o CONSTANT - immutable
See Also: Qualifier.getUnknownRV |
| negateCompareResult | | public boolean negateCompareResult()(Code) | | Should the result from the compare operation be negated? If true
then only rows which fail the compare operation will qualify.
See Also: Qualifier.negateCompareResult |
| reinitialize | | public void reinitialize()(Code) | | This method reinitializes all the state of
the Qualifier. It is used to distinguish between
resetting something that is query invariant
and something that is constant over every
execution of a query. Basically, clearOrderableCache()
will only clear out its cache if it is a VARIANT
or SCAN_INVARIANT value. However, each time a
query is executed, the QUERY_INVARIANT qualifiers need
to be reset.
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