Package org.apache.derby.vti
Interface IFastPath
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public interface IFastPath
An internal api for VTIs to allow VTI's written in terms of the datatype system, e.g. returning rows. This allows passing of data from the VTI into the query engine without a conversion through a JDBC ResultSet.
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Field Summary
Fields Modifier and Type Field Description static int
GOT_ROW
Indicates nextRow() found a row..static int
NEED_RS
Indicates nextRow() has completed its scan but executeQuery must be called to complete the query.static int
SCAN_COMPLETED
Indicates nextRow() has completed its scan.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
currentRow(java.sql.ResultSet rs, DataValueDescriptor[] row)
A call from the VTI execution layer back into the supplied VTI.boolean
executeAsFastPath()
Start a query.int
nextRow(DataValueDescriptor[] row)
When operating in fast path mode return the next row into the passed in row parameter.void
rowsDone()
Called once the ResultSet returned by executeQuery() has emptied all of its rows (next() has returned false).
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Field Detail
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SCAN_COMPLETED
static final int SCAN_COMPLETED
Indicates nextRow() has completed its scan.- See Also:
- Constant Field Values
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GOT_ROW
static final int GOT_ROW
Indicates nextRow() found a row..- See Also:
- Constant Field Values
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NEED_RS
static final int NEED_RS
Indicates nextRow() has completed its scan but executeQuery must be called to complete the query.- See Also:
- Constant Field Values
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Method Detail
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executeAsFastPath
boolean executeAsFastPath() throws StandardException, java.sql.SQLException
Start a query. Returns true if the VTI will start out as a fast path query and thus rows will be returned by nextRow(). Returns false if the engine must call the VTI's PreparedStatement.executeQuery() method to execute as a regular ResultSet VTI.- Throws:
StandardException
java.sql.SQLException
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nextRow
int nextRow(DataValueDescriptor[] row) throws StandardException, java.sql.SQLException
When operating in fast path mode return the next row into the passed in row parameter. Returns GOT_ROW if a valid row is found. Returns SCAN_COMPLETED if the scan is complete. Returns NEED_RS if the rest of the query must be handled as a regular ResultSet VTI by the engine calling the VTI's PreparedStatement.executeQuery()- Throws:
StandardException
java.sql.SQLException
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currentRow
void currentRow(java.sql.ResultSet rs, DataValueDescriptor[] row) throws StandardException, java.sql.SQLException
A call from the VTI execution layer back into the supplied VTI. Presents the row just processed as an array of DataValueDescriptors. This only called when the VTI is being executed as a regular ResultSet VTI- Throws:
StandardException
java.sql.SQLException
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rowsDone
void rowsDone() throws StandardException, java.sql.SQLException
Called once the ResultSet returned by executeQuery() has emptied all of its rows (next() has returned false).- Throws:
StandardException
java.sql.SQLException
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