org.apache.derby.impl.sql.compile
Class RowOrderingImpl

java.lang.Object
  org.apache.derby.impl.sql.compile.RowOrderingImpl

All Implemented Interfaces:

RowOrdering

 class RowOrderingImpl
extends java.lang.Object
implements RowOrdering

Field Summary

private java.util.ArrayList	alwaysOrderedOptimizables
(package private) ColumnOrdering	columnsAlwaysOrdered
(package private) ColumnOrdering	currentColumnOrdering
private java.util.ArrayList	ordering
private java.util.ArrayList	unorderedOptimizables

Fields inherited from interface org.apache.derby.iapi.sql.compile.RowOrdering

ASCENDING, DESCENDING, DONTCARE

Constructor Summary

RowOrderingImpl()

Method Summary

void	addOrderedColumn(int direction, int tableNumber, int columnNumber) Add a column to this RowOrdering in the current order position.
void	addUnorderedOptimizable(Optimizable optimizable) Add an unordered optimizable to this RowOrdering.
boolean	alwaysOrdered(int tableNumber) Ask whether the given table is always ordered.
void	columnAlwaysOrdered(Optimizable optimizable, int columnNumber) Tell this RowOrdering that it is always ordered on the given column of the given optimizable.
void	copy(RowOrdering copyTo) Copy the contents of this RowOrdering to the given RowOrdering.
boolean	isColumnAlwaysOrdered(int tableNumber, int columnNumber) Return true if the column is always ordered.
void	nextOrderPosition(int direction) Move to the next order position for adding ordered columns.
void	optimizableAlwaysOrdered(Optimizable optimizable) Tell this RowOrdering that it is always ordered on the given optimizable This is useful when considering a unique index where there is an equality match on the entire key - in this case, all the columns are ordered, regardless of the direction or position, or even whether the columns are in the index.
boolean	orderedOnColumn(int direction, int tableNumber, int columnNumber) Tell whether this ordering is ordered on the given column.
boolean	orderedOnColumn(int direction, int orderPosition, int tableNumber, int columnNumber) Tell whether this ordering is ordered on the given column in the given position
private void	rememberCurrentColumnOrdering(int posn)
void	removeOptimizable(int tableNumber) Tell this row ordering that it is no longer ordered on the given table.
private void	removeOptimizableFromVector(int tableNumber, java.util.ArrayList vec) Remove all optimizables with the given table number from the given vector of optimizables.
java.lang.String	toString()
private boolean	unorderedOptimizablesOtherThan(Optimizable optimizable) Returns true if there are unordered optimizables in the join order other than the given one.
private boolean	vectorContainsOptimizable(int tableNumber, java.util.ArrayList vec) Return true if the given vector of Optimizables contains an Optimizable with the given table number.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

ordering

private final java.util.ArrayList ordering

columnsAlwaysOrdered

ColumnOrdering columnsAlwaysOrdered

alwaysOrderedOptimizables

private final java.util.ArrayList alwaysOrderedOptimizables

currentColumnOrdering

ColumnOrdering currentColumnOrdering

unorderedOptimizables

private final java.util.ArrayList unorderedOptimizables

Constructor Detail

RowOrderingImpl

RowOrderingImpl()

Method Detail

isColumnAlwaysOrdered

public boolean isColumnAlwaysOrdered(int tableNumber,
                                     int columnNumber)

Description copied from interface: RowOrdering

Return true if the column is always ordered. That will be true if the column has a constant comparison predicate on it or it is involved in a equijoin with an optimizable which is always ordered on the column on which the equijoin is happening.

Specified by:

isColumnAlwaysOrdered in interface RowOrdering

Parameters:

tableNumber - The table in question

columnNumber - The number of the column in question.

Returns:

true means this column is always ordered

See Also:

RowOrdering.isColumnAlwaysOrdered(int, int)

orderedOnColumn

public boolean orderedOnColumn(int direction,
                               int orderPosition,
                               int tableNumber,
                               int columnNumber)
                        throws StandardException

Description copied from interface: RowOrdering

Tell whether this ordering is ordered on the given column in the given position

Specified by:

orderedOnColumn in interface RowOrdering

Parameters:

direction - One of ASCENDING, DESCENDING, or DONTCARE depending on the requirements of the caller. An ORDER BY clause cares about direction, while DISTINCT and GROUP BY do not.

orderPosition - The position in the ordering list. For example, for ORDER BY A, B, position 0 has column A, and position 1 has column B. Note that for an ordering, more than one column can be in a single ordering position: for example, in the query SELECT * FROM S, T WHERE S.A = T.B ORDER BY T.B columns S.A and T.B will be in the same ordering positions because they are equal. Also, constant values are considered ordered in all positions (consider SELECT A FROM T WHERE A = 1 ORDER BY A).

tableNumber - The table number of the Optimizable containing the column in question

columnNumber - The column number in the table (one-based).

Returns:

true means this ordering is ordered on the given column in the given position.

Throws:

StandardException - Thrown on error

See Also:

RowOrdering.orderedOnColumn(int, int, int, int)

orderedOnColumn

public boolean orderedOnColumn(int direction,
                               int tableNumber,
                               int columnNumber)
                        throws StandardException

Description copied from interface: RowOrdering

Tell whether this ordering is ordered on the given column. This is similar to the method above, but it checks whether the column is ordered in any position, rather than a specified position. This is useful for operations like DISTINCT and GROUP BY.

Specified by:

orderedOnColumn in interface RowOrdering

Parameters:

direction - One of ASCENDING, DESCENDING, or DONTCARE depending on the requirements of the caller. An ORDER BY clause cares about direction, while DISTINCT and GROUP BY do not.

tableNumber - The table number of the Optimizable containing the column in question

columnNumber - The column number in the table (one-based).

Returns:

true means this ordering is ordered on the given column in the given position.

Throws:

StandardException - Thrown on error

See Also:

RowOrdering.orderedOnColumn(int, int, int, int)

vectorContainsOptimizable

private boolean vectorContainsOptimizable(int tableNumber,
                                          java.util.ArrayList vec)

Return true if the given vector of Optimizables contains an Optimizable with the given table number.

addOrderedColumn

public void addOrderedColumn(int direction,
                             int tableNumber,
                             int columnNumber)

Description copied from interface: RowOrdering

Add a column to this RowOrdering in the current order position. This is a no-op if there are any unordered optimizables in the join order (see below).

Specified by:

addOrderedColumn in interface RowOrdering

Parameters:

direction - One of ASCENDING, DESCENDING, or DONTCARE. DONTCARE can be used for things like columns with constant value, and for one-row tables.

tableNumber - The table the column is in.

columnNumber - The column number in the table (one-based)

See Also:

RowOrdering.addOrderedColumn(int, int, int)

nextOrderPosition

public void nextOrderPosition(int direction)

Description copied from interface: RowOrdering

Move to the next order position for adding ordered columns. This is a no-op if there are any unordered optimizables in the join order (see below).

Specified by:

nextOrderPosition in interface RowOrdering

Parameters:

direction - One of ASCENDING, DESCENDING, or DONTCARE. DONTCARE can be used for things like columns with constant value, and for one-row tables.

See Also:

RowOrdering.nextOrderPosition(int)

optimizableAlwaysOrdered

public void optimizableAlwaysOrdered(Optimizable optimizable)

Description copied from interface: RowOrdering

Tell this RowOrdering that it is always ordered on the given optimizable This is useful when considering a unique index where there is an equality match on the entire key - in this case, all the columns are ordered, regardless of the direction or position, or even whether the columns are in the index.

Specified by:

optimizableAlwaysOrdered in interface RowOrdering

Parameters:

optimizable - The table in question

columnAlwaysOrdered

public void columnAlwaysOrdered(Optimizable optimizable,
                                int columnNumber)

Description copied from interface: RowOrdering

Tell this RowOrdering that it is always ordered on the given column of the given optimizable. This is useful when a column in the optimizable has an equals comparison with a constant expression or it is involved in a equijoin with an optimizable which is always ordered on the column on which the equijoin is happening. This is reset when the optimizable is removed from this RowOrdering.

Specified by:

columnAlwaysOrdered in interface RowOrdering

Parameters:

optimizable - The table in question

columnNumber - The number of the column in question.

See Also:

RowOrdering.columnAlwaysOrdered(org.apache.derby.iapi.sql.compile.Optimizable, int)

alwaysOrdered

public boolean alwaysOrdered(int tableNumber)

Description copied from interface: RowOrdering

Ask whether the given table is always ordered.

Specified by:

alwaysOrdered in interface RowOrdering

See Also:

RowOrdering.alwaysOrdered(int)

removeOptimizable

public void removeOptimizable(int tableNumber)

Description copied from interface: RowOrdering

Tell this row ordering that it is no longer ordered on the given table. Also, adjust the current order position, if necessary. This only works to remove ordered columns from the end of the ordering.

Specified by:

removeOptimizable in interface RowOrdering

Parameters:

tableNumber - The number of the table to remove from this RowOrdering.

See Also:

RowOrdering.removeOptimizable(int)

removeOptimizableFromVector

private void removeOptimizableFromVector(int tableNumber,
                                         java.util.ArrayList vec)

Remove all optimizables with the given table number from the given vector of optimizables.

addUnorderedOptimizable

public void addUnorderedOptimizable(Optimizable optimizable)

Description copied from interface: RowOrdering

Add an unordered optimizable to this RowOrdering. This is to solve the following problem: Suppose we have the query: select * from r, s, t order by r.a, t.b Also suppose there are indexes on r.a and t.b. When the optimizer considers the join order (r, s, t) using the index on r.a, the heap on s, and the index on t.b, the rows from the join order will *NOT* be ordered on t.b, because there is an unordered result set between r and t. So, when s is added to the partial join order, and we then add table t to the join order, we want to ensure that we don't add column t.b to the RowOrdering.

Specified by:

addUnorderedOptimizable in interface RowOrdering

See Also:

RowOrdering.addUnorderedOptimizable(org.apache.derby.iapi.sql.compile.Optimizable)

copy

public void copy(RowOrdering copyTo)

Description copied from interface: RowOrdering

Copy the contents of this RowOrdering to the given RowOrdering.

Specified by:

copy in interface RowOrdering

See Also:

RowOrdering.copy(org.apache.derby.iapi.sql.compile.RowOrdering)

rememberCurrentColumnOrdering

private void rememberCurrentColumnOrdering(int posn)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

unorderedOptimizablesOtherThan

private boolean unorderedOptimizablesOtherThan(Optimizable optimizable)

Returns true if there are unordered optimizables in the join order other than the given one.