Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.iapi.sql.compile.RowOrdering

Modifier and Type	Field and Description
public static final int	ASCENDING
public static final int	DESCENDING
public static final int	DONTCARE

Method Summary

Modifier and Type	Method and Description
public void	addOrderedColumn(int One of ASCENDING, DESCENDING, or DONTCARE. DONTCARE can be used for things like columns with constant value, and for one-row tables. direction, int The table the column is in. tableNumber, int The column number in the table (one-based) columnNumber) Add a column to this RowOrdering in the current order position.
public void	addUnorderedOptimizable(Optimizable optimizable) Add an unordered optimizable to this RowOrdering.
public boolean	alwaysOrdered(int tableNumber) Ask whether the given table is always ordered.
public void	columnAlwaysOrdered(Optimizable The table in question optimizable, int The number of the column in question. columnNumber) Tell this RowOrdering that it is always ordered on the given column of the given optimizable.
public void	copy(RowOrdering copyTo) Copy the contents of this RowOrdering to the given RowOrdering.
public boolean	Returns: true means this column is always ordered isColumnAlwaysOrdered(int The table in question tableNumber, int The number of the column in question. columnNumber) Return true if the column is always ordered.
public void	nextOrderPosition(int One of ASCENDING, DESCENDING, or DONTCARE. DONTCARE can be used for things like columns with constant value, and for one-row tables. direction) Move to the next order position for adding ordered columns.
public void	optimizableAlwaysOrdered(Optimizable The table in question 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.
public boolean	Returns: true means this ordering is ordered on the given column in the given position. orderedOnColumn(int 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. direction, int 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). orderPosition, int The table number of the Optimizable containing the column in question tableNumber, int The column number in the table (one-based). columnNumber) Tell whether this ordering is ordered on the given column in the given position
public boolean	Returns: true means this ordering is ordered on the given column in the given position. orderedOnColumn(int 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. direction, int The table number of the Optimizable containing the column in question tableNumber, int The column number in the table (one-based). columnNumber) Tell whether this ordering is ordered on the given column.
public void	removeOptimizable(int The number of the table to remove from this RowOrdering. tableNumber) Tell this row ordering that it is no longer ordered on the given table.

ASCENDING	back to summary
public static final int ASCENDING

DESCENDING	back to summary
public static final int DESCENDING

DONTCARE	back to summary
public static final int DONTCARE

Method Detail

addOrderedColumn	back to summary
public void addOrderedColumn(int direction, int tableNumber, int columnNumber) 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). Parameters direction:int One of ASCENDING, DESCENDING, or DONTCARE. DONTCARE can be used for things like columns with constant value, and for one-row tables. tableNumber:int The table the column is in. columnNumber:int The column number in the table (one-based)

addOrderedColumn

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

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).

Parameters

direction:int: One of ASCENDING, DESCENDING, or DONTCARE. DONTCARE can be used for things like columns with constant value, and for one-row tables.
tableNumber:int: The table the column is in.
columnNumber:int: The column number in the table (one-based)

addUnorderedOptimizable	back to summary
public void addUnorderedOptimizable(Optimizable optimizable) 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.

addUnorderedOptimizable

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public void addUnorderedOptimizable(Optimizable optimizable)

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.

alwaysOrdered	back to summary
public boolean alwaysOrdered(int tableNumber) Ask whether the given table is always ordered.

columnAlwaysOrdered	back to summary
public void columnAlwaysOrdered(Optimizable optimizable, int columnNumber) 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. Parameters optimizable:Optimizable The table in question columnNumber:int The number of the column in question.

columnAlwaysOrdered

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public void columnAlwaysOrdered(Optimizable optimizable, int columnNumber)

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.

Parameters

optimizable:Optimizable: The table in question
columnNumber:int: The number of the column in question.

copy	back to summary
public void copy(RowOrdering copyTo) Copy the contents of this RowOrdering to the given RowOrdering.

isColumnAlwaysOrdered	back to summary
public boolean isColumnAlwaysOrdered(int tableNumber, int columnNumber) 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. Parameters tableNumber:int The table in question columnNumber:int The number of the column in question. Returns:boolean true means this column is always ordered

isColumnAlwaysOrdered

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public boolean isColumnAlwaysOrdered(int tableNumber, int columnNumber)

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.

Parameters

tableNumber:int: The table in question
columnNumber:int: The number of the column in question.

Returns:boolean

true means this column is always ordered

nextOrderPosition	back to summary
public void nextOrderPosition(int direction) 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). Parameters direction:int One of ASCENDING, DESCENDING, or DONTCARE. DONTCARE can be used for things like columns with constant value, and for one-row tables.

nextOrderPosition

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public void nextOrderPosition(int direction)

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).

Parameters

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

optimizableAlwaysOrdered	back to summary
public 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. Parameters optimizable:Optimizable The table in question

optimizableAlwaysOrdered

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public 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.

Parameters

optimizable:Optimizable: The table in question

orderedOnColumn	back to summary
public boolean orderedOnColumn(int direction, int orderPosition, int tableNumber, int columnNumber) throws StandardException Tell whether this ordering is ordered on the given column in the given position Parameters direction:int 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:int 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:int The table number of the Optimizable containing the column in question columnNumber:int The column number in the table (one-based). Returns:boolean true means this ordering is ordered on the given column in the given position. Exceptions StandardException: Thrown on error

orderedOnColumn

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

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

Parameters

direction:int: 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:int: 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:int: The table number of the Optimizable containing the column in question
columnNumber:int: The column number in the table (one-based).

Returns:boolean

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

Exceptions

StandardException:: Thrown on error

orderedOnColumn	back to summary
public boolean orderedOnColumn(int direction, int tableNumber, int columnNumber) throws StandardException 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. Parameters direction:int 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:int The table number of the Optimizable containing the column in question columnNumber:int The column number in the table (one-based). Returns:boolean true means this ordering is ordered on the given column in the given position. Exceptions StandardException: Thrown on error

orderedOnColumn

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

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.

Parameters

direction:int: 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:int: The table number of the Optimizable containing the column in question
columnNumber:int: The column number in the table (one-based).

Returns:boolean

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

Exceptions

StandardException:: Thrown on error

removeOptimizable	back to summary
public void removeOptimizable(int tableNumber) 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. Parameters tableNumber:int The number of the table to remove from this RowOrdering.

removeOptimizable

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public void removeOptimizable(int tableNumber)

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.

Parameters

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

public Interface RowOrdering

Field Summary

Method Summary

Field Detail

Method Detail