Class SortBufferRowSource
- All Implemented Interfaces:
ScanControllerRowSource
,ScanManager
,GenericScanController
,GroupFetchScanController
,RowCountable
,RowLocationRetRowSource
,RowSource
,ScanController
,ScanInfo
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate int
(package private) SortBuffer
The Sort buffer where rows come fromprivate SortObserver
protected TransactionManager
The TransactionManager that opened this scan.private boolean
Fields inherited from interface org.apache.derby.iapi.store.access.ScanController
GE, GT, NA
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Constructor Summary
ConstructorsConstructorDescriptionSortBufferRowSource
(SortBuffer sortBuffer, TransactionManager tran, SortObserver sortObserver, boolean writingToDisk, int maxFreeListSize) -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Close the scanboolean
closeForEndTransaction
(boolean closeHeldScan) Close the scanvoid
Close the rowSourcevoid
fetch
(DataValueDescriptor[] result) Fetch the row at the current position of the Scan.final boolean
fetchNext
(DataValueDescriptor[] row) Fetch the (partial) row at the next position of the Scan.void
fetchWithoutQualify
(DataValueDescriptor[] result) Fetch the row at the current position of the Scan and does not apply the qualifiers.Get the next row as an array of column objects.All columns are always set from a sorterboolean
needsRowLocation returns true iff this the row source expects the drainer of the row source to call rowLocation after getting a row from getNextRowFromRowSource.boolean
boolean
Does the caller of getNextRowFromRowSource() need to clone the row in order to keep a reference to the row past the getNextRowFromRowSource() call which returned the row.boolean
next()
Move to the next position in the scan.void
offendingRowLocation
(RowLocation rl, long containdId) void
rowLocation is a callback for the drainer of the row source to return the rowLocation of the current row, i.e, the row that is being returned by getNextRowFromRowSource.Methods inherited from class org.apache.derby.impl.store.access.sort.Scan
delete, didNotQualify, doesCurrentPositionQualify, fetchLocation, fetchNextGroup, fetchNextGroup, fetchSet, getAllScanInfo, getEstimatedRowCount, getScanInfo, isCurrentPositionDeleted, isHeldAfterCommit, isKeyed, isTableLocked, newRowLocationTemplate, positionAtRowLocation, reopenScan, reopenScanByRowLocation, replace, setEstimatedRowCount
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface org.apache.derby.iapi.store.access.GenericScanController
getScanInfo, isKeyed, isTableLocked, newRowLocationTemplate, reopenScan, reopenScanByRowLocation
Methods inherited from interface org.apache.derby.iapi.store.access.RowCountable
getEstimatedRowCount, setEstimatedRowCount
Methods inherited from interface org.apache.derby.iapi.store.access.ScanController
delete, didNotQualify, doesCurrentPositionQualify, fetchLocation, isCurrentPositionDeleted, isHeldAfterCommit, positionAtRowLocation, replace
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Field Details
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sortBuffer
SortBuffer sortBufferThe Sort buffer where rows come from -
tran
The TransactionManager that opened this scan. -
maxFreeListSize
private int maxFreeListSize -
writingToDisk
private boolean writingToDisk -
sortObserver
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Constructor Details
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SortBufferRowSource
SortBufferRowSource(SortBuffer sortBuffer, TransactionManager tran, SortObserver sortObserver, boolean writingToDisk, int maxFreeListSize)
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Method Details
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getNextRowFromRowSource
Description copied from interface:RowSource
Get the next row as an array of column objects. The column objects can be a JBMS Storable or any Serializable/Externalizable/Formattable/Streaming type.
A return of null indicates that the complete set of rows has been read.A null column can be specified by leaving the object null, or indicated by returning a non-null getValidColumns. On streaming columns, it can be indicated by returning a non-null get FieldStates.
If RowSource.needToClone() is true then the returned row (the DataValueDescriptor[]) is guaranteed not to be modified by drainer of the RowSource (except that the input stream will be read, of course) and drainer will keep no reference to it before making the subsequent nextRow call. So it is safe to return the same DataValueDescriptor[] in subsequent nextRow calls if that is desirable for performance reasons.
If RowSource.needToClone() is false then the returned row (the DataValueDescriptor[]) may be be modified by drainer of the RowSource, and the drainer may keep a reference to it after making the subsequent nextRow call. In this case the client should severe all references to the row after returning it from getNextRowFromRowSource().
- Specified by:
getNextRowFromRowSource
in interfaceRowSource
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needsRowLocation
public boolean needsRowLocation()Description copied from interface:RowLocationRetRowSource
needsRowLocation returns true iff this the row source expects the drainer of the row source to call rowLocation after getting a row from getNextRowFromRowSource.- Specified by:
needsRowLocation
in interfaceRowLocationRetRowSource
- Returns:
- true iff this row source expects some row location to be returned
- See Also:
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needsRowLocationForDeferredCheckConstraints
public boolean needsRowLocationForDeferredCheckConstraints()- Specified by:
needsRowLocationForDeferredCheckConstraints
in interfaceRowLocationRetRowSource
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needsToClone
public boolean needsToClone()Description copied from interface:RowSource
Does the caller of getNextRowFromRowSource() need to clone the row in order to keep a reference to the row past the getNextRowFromRowSource() call which returned the row. This call must always return the same for all rows in a RowSource (ie. the caller will call this once per scan from a RowSource and assume the behavior is true for all rows in the RowSource).- Specified by:
needsToClone
in interfaceRowSource
- See Also:
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rowLocation
Description copied from interface:RowLocationRetRowSource
rowLocation is a callback for the drainer of the row source to return the rowLocation of the current row, i.e, the row that is being returned by getNextRowFromRowSource. This interface is for the purpose of loading a base table with index. In that case, the indices can be built at the same time the base table is laid down once the row location of the base row is known. This is an example pseudo code on how this call is expected to be used:boolean needsRL = rowSource.needsRowLocation(); DataValueDescriptor[] row; while((row = rowSource.getNextRowFromRowSource()) != null) { RowLocation rl = heapConglomerate.insertRow(row); if (needsRL) rowSource.rowLocation(rl); }
NeedsRowLocation and rowLocation will ONLY be called by a drainer of the row source which CAN return a row location. Drainer of row source which cannot return rowLocation will guarantee to not call either callbacks. Conversely, if NeedsRowLocation is called and it returns true, then for every row return by getNextRowFromRowSource, a rowLocation callback must also be issued with the row location of the row. Implementor of both the source and the drain of the row source must be aware of this protocol.
The RowLocation object is own by the caller of rowLocation, in other words, the drainer of the RowSource. This is so that we don't need to new a row location for every row. If the Row Source wants to keep the row location, it needs to clone it (RowLocation is a ClonableObject).- Specified by:
rowLocation
in interfaceRowLocationRetRowSource
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offendingRowLocation
- Specified by:
offendingRowLocation
in interfaceRowLocationRetRowSource
- Throws:
StandardException
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getValidColumns
All columns are always set from a sorter- Specified by:
getValidColumns
in interfaceRowSource
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close
public void close()Close the scan- Specified by:
close
in interfaceGenericScanController
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closeForEndTransaction
public boolean closeForEndTransaction(boolean closeHeldScan) Close the scan- Specified by:
closeForEndTransaction
in interfaceScanManager
- Parameters:
closeHeldScan
- If true, means to close scan even if it has been opened to be kept opened across commit. This is used to close these scans on abort.- Returns:
- boolean indicating that the close has resulted in a real close of the scan. A held scan will return false if called by closeForEndTransaction(false), otherwise it will return true. A non-held scan will always return true.
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closeRowSource
public void closeRowSource()Close the rowSource- Specified by:
closeRowSource
in interfaceRowSource
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next
Description copied from interface:ScanController
Move to the next position in the scan. If this is the first call to next(), the position is set to the first row. Returns false if there is not a next row to move to. It is possible, but not guaranteed, that this method could return true again, after returning false, if some other operation in the same transaction appended a row to the underlying conglomerate.- Specified by:
next
in interfaceGroupFetchScanController
- Specified by:
next
in interfaceScanController
- Returns:
- True if there is a next position in the scan, false if there isn't.
- Throws:
StandardException
- Standard exception policy.
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fetchWithoutQualify
Fetch the row at the current position of the Scan and does not apply the qualifiers. This method will always throw an exception. (SQLState.SORT_IMPROPER_SCAN_METHOD)- Specified by:
fetchWithoutQualify
in interfaceScanController
- Parameters:
result
- The row into which the value of the current position in the scan is to be stored.- Throws:
StandardException
- Standard exception policy.- See Also:
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fetch
Fetch the row at the current position of the Scan.- Specified by:
fetch
in interfaceScanController
- Parameters:
result
- The row into which the value of the current position in the scan is to be stored.- Throws:
StandardException
- Standard exception policy.- See Also:
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fetchNext
Description copied from interface:ScanController
Fetch the (partial) row at the next position of the Scan. If there is a valid next position in the scan then the value in the destRow storable row is replaced with the value of the row at the current scan position. The columns of the destRow row must be of the same type as the actual columns in the underlying conglomerate. The resulting contents of destRow after a fetchNext() which returns false is undefined. The result of calling fetchNext(row) is exactly logically equivalent to making a next() call followed by a fetch(row) call. This interface allows implementations to optimize the 2 calls if possible.- Specified by:
fetchNext
in interfaceScanController
- Parameters:
row
- The destRow row into which the value of the next position in the scan is to be stored.- Returns:
- True if there is a next position in the scan, false if there isn't.
- Throws:
StandardException
- Standard exception policy.- See Also:
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