Package org.apache.derby.vti
Interface IFastPath
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
FieldsModifier and TypeFieldDescriptionstatic final int
Indicates nextRow() found a row..static final int
Indicates nextRow() has completed its scan but executeQuery must be called to complete the query.static final int
Indicates nextRow() has completed its scan. -
Method Summary
Modifier and TypeMethodDescriptionvoid
currentRow
(ResultSet rs, DataValueDescriptor[] row) A call from the VTI execution layer back into the supplied VTI.boolean
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 Details
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SCAN_COMPLETED
static final int SCAN_COMPLETEDIndicates nextRow() has completed its scan.- See Also:
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GOT_ROW
static final int GOT_ROWIndicates nextRow() found a row..- See Also:
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NEED_RS
static final int NEED_RSIndicates nextRow() has completed its scan but executeQuery must be called to complete the query.- See Also:
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Method Details
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executeAsFastPath
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
SQLException
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nextRow
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
SQLException
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currentRow
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
SQLException
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rowsDone
Called once the ResultSet returned by executeQuery() has emptied all of its rows (next() has returned false).- Throws:
StandardException
SQLException
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