Quadcap Embeddable Database

com.quadcap.sql.MergeCursor Class Reference

Inheritance diagram for com.quadcap.sql.MergeCursor:

List of all members.

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Detailed Description

Cursor implementing the SQL UNION or INTERSECTION operations.

This cursor shares some functionality with the GroupByCursor class, and factorization should be investigated.

Author:

Stan Bailes

Definition at line 72 of file MergeCursor.java.

Public Member Functions
	MergeCursor (Session session, int op, boolean all, TempTableMerge tempTable) throws SQLException
Row	getRow () throws SQLException
	Derived class implements this function to return the current cursor row.
void	checkCursor () throws IOException
long	getRowId ()
	Some cursors have rows where the rows can be identified by row id, and sometimes the cursors even know the row id for the current row.
void	resolveColumns () throws SQLException
	Once all of the column names are available, we can look for duplicates and shortest-unique names, etc.
String	getName ()
	Return the tuple's name.
long	size () throws SQLException
	If the underlying implementation knows, or can compute cheaply, the actual size of the ResultSet, it should return a non-negative number here.
void	afterLast () throws SQLException
	Position the cursor after the last row.
boolean	isWritable (int col)
	Return true if the specified column is writable.
boolean	next () throws SQLException
	Advance the cursor and return true if we advanced to a valid row.
void	updateRow (Row row) throws SQLException
	Replace the current cursor row with the specified row.
void	deleteRow () throws SQLException
	Delete the current cursor row.
void	beforeFirst () throws SQLException
	Position the cursor before the first row.
void	close () throws SQLException
	On close, we release the resources.
Package Functions
boolean	nextUnion () throws SQLException, IOException
	Separate from 'nextUnionAll' because we can avoid fetching the data for this case.
boolean	nextUnionAll () throws SQLException, IOException
	Fetch the data once when we fetch the counts, then return each row the required number of times.
boolean	nextIntersect () throws SQLException, IOException
boolean	nextExcept () throws SQLException, IOException
Package Attributes
int	op
boolean	all
TempTableMerge	tempTable
LazyRow	row = null
BCursor	bc = null
int	duplicateCount = 0

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Constructor & Destructor Documentation

com.quadcap.sql.MergeCursor.MergeCursor (  Session  session, int  op, boolean  all, TempTableMerge  tempTable )  throws SQLException

Definition at line 80 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.all, com.quadcap.sql.MergeCursor.op, and com.quadcap.sql.MergeCursor.tempTable.

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Member Function Documentation

void com.quadcap.sql.MergeCursor.afterLast (   )  throws SQLException [virtual]

Position the cursor after the last row. Implements com.quadcap.sql.CursorImpl. Definition at line 122 of file MergeCursor.java.

void com.quadcap.sql.MergeCursor.beforeFirst (   )  throws SQLException [virtual]

Position the cursor before the first row. Implements com.quadcap.sql.CursorImpl. Definition at line 156 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.bc, com.quadcap.sql.MergeCursor.checkCursor(), and com.quadcap.sql.MergeCursor.duplicateCount. Referenced by com.quadcap.sql.MergeCursor.resolveColumns().

void com.quadcap.sql.MergeCursor.checkCursor (   )  throws IOException

Definition at line 94 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.bc, com.quadcap.sql.TempTable.getCursor(), and com.quadcap.sql.MergeCursor.tempTable. Referenced by com.quadcap.sql.MergeCursor.beforeFirst(), com.quadcap.sql.MergeCursor.next(), and com.quadcap.sql.MergeCursor.size().

void com.quadcap.sql.MergeCursor.close (   )  throws SQLException [virtual]

On close, we release the resources. Implements com.quadcap.sql.CursorImpl. Definition at line 241 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.bc, com.quadcap.sql.TempTable.release(), and com.quadcap.sql.MergeCursor.tempTable.

void com.quadcap.sql.MergeCursor.deleteRow (   )  throws SQLException [virtual]

Delete the current cursor row. Implements com.quadcap.sql.CursorImpl. Definition at line 151 of file MergeCursor.java.

String com.quadcap.sql.MergeCursor.getName (   )

Return the tuple's name. Reimplemented from com.quadcap.sql.TupleImpl. Definition at line 111 of file MergeCursor.java.

Row com.quadcap.sql.MergeCursor.getRow (   )  throws SQLException [virtual]

Derived class implements this function to return the current cursor row. Implementation required. Implements com.quadcap.sql.CursorImpl. Definition at line 90 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.row.

long com.quadcap.sql.MergeCursor.getRowId (   )

Some cursors have rows where the rows can be identified by row id, and sometimes the cursors even know the row id for the current row. If you know, tell us here! If you don't know, just return 0. Reimplemented from com.quadcap.sql.CursorImpl. Definition at line 100 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.bc.

boolean com.quadcap.sql.MergeCursor.isWritable (  int  col  )  [virtual]

Return true if the specified column is writable. Parameters: column  the (one-based) column number Exceptions: SQLException  may be thrown Implements com.quadcap.sql.CursorImpl. Definition at line 126 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.isWritable(). Referenced by com.quadcap.sql.MergeCursor.isWritable().

boolean com.quadcap.sql.MergeCursor.next (   )  throws SQLException [virtual]

Advance the cursor and return true if we advanced to a valid row. Implements com.quadcap.sql.CursorImpl. Definition at line 128 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.all, com.quadcap.sql.MergeCursor.checkCursor(), com.quadcap.sql.MergeCursor.nextExcept(), com.quadcap.sql.MergeCursor.nextIntersect(), com.quadcap.sql.MergeCursor.nextUnion(), com.quadcap.sql.MergeCursor.nextUnionAll(), and com.quadcap.sql.MergeCursor.op.

boolean com.quadcap.sql.MergeCursor.nextExcept (   )  throws SQLException, IOException [package]

Definition at line 216 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.all, com.quadcap.sql.MergeCursor.bc, com.quadcap.sql.MergeCursor.duplicateCount, com.quadcap.sql.TempTable.getRow(), com.quadcap.sql.MergeCursor.row, and com.quadcap.sql.MergeCursor.tempTable. Referenced by com.quadcap.sql.MergeCursor.next().

boolean com.quadcap.sql.MergeCursor.nextIntersect (   )  throws SQLException, IOException [package]

Definition at line 194 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.all, com.quadcap.sql.MergeCursor.bc, com.quadcap.sql.MergeCursor.duplicateCount, com.quadcap.sql.TempTable.getRow(), com.quadcap.sql.MergeCursor.row, and com.quadcap.sql.MergeCursor.tempTable. Referenced by com.quadcap.sql.MergeCursor.next().

boolean com.quadcap.sql.MergeCursor.nextUnion (   )  throws SQLException, IOException [package]

Separate from 'nextUnionAll' because we can avoid fetching the data for this case. Definition at line 171 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.bc, com.quadcap.sql.TempTable.getRow(), com.quadcap.sql.MergeCursor.row, and com.quadcap.sql.MergeCursor.tempTable. Referenced by com.quadcap.sql.MergeCursor.next().

boolean com.quadcap.sql.MergeCursor.nextUnionAll (   )  throws SQLException, IOException [package]

Fetch the data once when we fetch the counts, then return each row the required number of times. Definition at line 181 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.bc, com.quadcap.sql.MergeCursor.duplicateCount, com.quadcap.sql.TempTable.getRow(), com.quadcap.sql.MergeCursor.row, and com.quadcap.sql.MergeCursor.tempTable. Referenced by com.quadcap.sql.MergeCursor.next().

void com.quadcap.sql.MergeCursor.resolveColumns (   )  throws SQLException

Once all of the column names are available, we can look for duplicates and shortest-unique names, etc. Reimplemented from com.quadcap.sql.TupleImpl. Definition at line 105 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.beforeFirst(), com.quadcap.sql.TupleImpl.getColumnCount(), and com.quadcap.sql.MergeCursor.row. Referenced by com.quadcap.sql.MergeExpression.getCursor().

long com.quadcap.sql.MergeCursor.size (   )  throws SQLException

If the underlying implementation knows, or can compute cheaply, the actual size of the ResultSet, it should return a non-negative number here. If the size is unknown and it would be expensive to compute it (i.e., on the order of while next()) size++), then the implementation should return -1 Implements com.quadcap.sql.Cursor. Definition at line 113 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.bc, and com.quadcap.sql.MergeCursor.checkCursor().

void com.quadcap.sql.MergeCursor.updateRow (  Row  row  )  throws SQLException [virtual]

Replace the current cursor row with the specified row. Implements com.quadcap.sql.CursorImpl. Definition at line 146 of file MergeCursor.java. References com.quadcap.sql.MergeCursor.updateRow(). Referenced by com.quadcap.sql.MergeCursor.updateRow().

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Member Data Documentation

boolean com.quadcap.sql.MergeCursor.all [package]

Definition at line 74 of file MergeCursor.java. Referenced by com.quadcap.sql.MergeCursor.MergeCursor(), com.quadcap.sql.MergeCursor.next(), com.quadcap.sql.MergeCursor.nextExcept(), and com.quadcap.sql.MergeCursor.nextIntersect().

BCursor com.quadcap.sql.MergeCursor.bc = null [package]

Definition at line 77 of file MergeCursor.java. Referenced by com.quadcap.sql.MergeCursor.beforeFirst(), com.quadcap.sql.MergeCursor.checkCursor(), com.quadcap.sql.MergeCursor.close(), com.quadcap.sql.MergeCursor.getRowId(), com.quadcap.sql.MergeCursor.nextExcept(), com.quadcap.sql.MergeCursor.nextIntersect(), com.quadcap.sql.MergeCursor.nextUnion(), com.quadcap.sql.MergeCursor.nextUnionAll(), and com.quadcap.sql.MergeCursor.size().

int com.quadcap.sql.MergeCursor.duplicateCount = 0 [package]

Definition at line 78 of file MergeCursor.java. Referenced by com.quadcap.sql.MergeCursor.beforeFirst(), com.quadcap.sql.MergeCursor.nextExcept(), com.quadcap.sql.MergeCursor.nextIntersect(), and com.quadcap.sql.MergeCursor.nextUnionAll().

int com.quadcap.sql.MergeCursor.op [package]

Definition at line 73 of file MergeCursor.java. Referenced by com.quadcap.sql.MergeCursor.MergeCursor(), and com.quadcap.sql.MergeCursor.next().

LazyRow com.quadcap.sql.MergeCursor.row = null [package]

Definition at line 76 of file MergeCursor.java. Referenced by com.quadcap.sql.MergeCursor.getRow(), com.quadcap.sql.MergeCursor.nextExcept(), com.quadcap.sql.MergeCursor.nextIntersect(), com.quadcap.sql.MergeCursor.nextUnion(), com.quadcap.sql.MergeCursor.nextUnionAll(), and com.quadcap.sql.MergeCursor.resolveColumns().

TempTableMerge com.quadcap.sql.MergeCursor.tempTable [package]

Definition at line 75 of file MergeCursor.java. Referenced by com.quadcap.sql.MergeCursor.checkCursor(), com.quadcap.sql.MergeCursor.close(), com.quadcap.sql.MergeCursor.MergeCursor(), com.quadcap.sql.MergeCursor.nextExcept(), com.quadcap.sql.MergeCursor.nextIntersect(), com.quadcap.sql.MergeCursor.nextUnion(), and com.quadcap.sql.MergeCursor.nextUnionAll().