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This interface provides a representation of the required ordering of rows from a ResultSet. Different operations can require ordering: ORDER BY, DISTINCT, GROUP BY. Some operations, like ORDER BY, require that the columns be ordered a particular way, while others, like DISTINCT and GROUP BY, reuire only that there be no duplicates in the result.
Field Summary | |
static int |
ELIMINATE_DUPS
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static int |
NOTHING_REQUIRED
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static int |
SORT_REQUIRED
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Method Summary | |
void |
estimateCost(double estimatedInputRows,
RowOrdering rowOrdering,
CostEstimate resultCost)
Estimate the cost of doing a sort for this row ordering, given the number of rows to be sorted. |
boolean |
getSortNeeded()
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void |
sortNeeded()
Indicate that a sort is necessary to fulfill this required ordering. |
void |
sortNotNeeded()
Indicate that a sort is *NOT* necessary to fulfill this required ordering. |
int |
sortRequired(RowOrdering rowOrdering)
Tell whether sorting is required for this RequiredRowOrdering, given a RowOrdering. |
int |
sortRequired(RowOrdering rowOrdering,
JBitSet tableMap)
Tell whether sorting is required for this RequiredRowOrdering, given a RowOrdering representing a partial join order, and a bit map telling what tables are represented in the join order. |
Field Detail |
public static final int SORT_REQUIRED
public static final int ELIMINATE_DUPS
public static final int NOTHING_REQUIRED
Method Detail |
public int sortRequired(RowOrdering rowOrdering) throws StandardException
rowOrdering
- The order of rows in question
StandardException
- Thrown on errorpublic int sortRequired(RowOrdering rowOrdering, JBitSet tableMap) throws StandardException
rowOrdering
- The order of rows in the partial join ordertableMap
- A bit map of the tables in the partial join order
StandardException
- Thrown on errorpublic void estimateCost(double estimatedInputRows, RowOrdering rowOrdering, CostEstimate resultCost) throws StandardException
estimatedInputRows
- The estimated number of rows to sortrowOrdering
- The ordering of the input rowsresultCost
- A place to store the resulting cost
StandardException
- Thrown on errorpublic void sortNeeded()
public void sortNotNeeded()
public boolean getSortNeeded()
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Built on Mon 2007-06-04 09:58:47+0400, from revision ??? | |||||||||
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