| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.impl.store.access.sort.MergeScanRowSource |
| 4 | |
| 5 | Copyright 1998, 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.impl.store.access.sort; |
| 22 | |
| 23 | import org.apache.derby.iapi.reference.SQLState; |
| 24 | |
| 25 | import org.apache.derby.iapi.services.io.FormatableBitSet; |
| 26 | import org.apache.derby.iapi.services.sanity.SanityManager; |
| 27 | |
| 28 | import org.apache.derby.iapi.error.StandardException; |
| 29 | import org.apache.derby.iapi.store.access.conglomerate.ScanControllerRowSource; |
| 30 | import org.apache.derby.iapi.store.access.conglomerate.TransactionManager; |
| 31 | import org.apache.derby.iapi.store.access.SortObserver; |
| 32 | import org.apache.derby.iapi.store.access.RowLocationRetRowSource; |
| 33 | |
| 34 | import org.apache.derby.iapi.types.DataValueDescriptor; |
| 35 | |
| 36 | import org.apache.derby.iapi.types.RowLocation; |
| 37 | |
| 38 | import java.util.Vector; |
| 39 | |
| 40 | /** |
| 41 | Wrapping the output of a MergeScan in a RowSource for the benefit of the |
| 42 | createAndLoadConglomerate and loadConglomerate interface. The output of a |
| 43 | |
| 44 | MergeScan is written to a file when we need more than one level of merge |
| 45 | runs. |
| 46 | |
| 47 | MergeScan implements ScanController, this class just implements the |
| 48 | RowSource interface. |
| 49 | */ |
| 50 | public class MergeScanRowSource extends MergeScan implements ScanControllerRowSource |
| 51 | { |
| 52 | |
| 53 | /* Constructors for This class: */ |
| 54 | MergeScanRowSource( |
| 55 | MergeSort sort, |
| 56 | TransactionManager tran, |
| 57 | SortBuffer sortBuffer, |
| 58 | Vector mergeRuns, |
| 59 | SortObserver sortObserver, |
| 60 | boolean hold) |
| 61 | { |
| 62 | super(sort, tran, sortBuffer, mergeRuns, sortObserver, hold); |
| 63 | } |
| 64 | |
| 65 | /* |
| 66 | * Disable illegal and dangerous scan controller interface call |
| 67 | * @exception StandardException This is an illegal operation |
| 68 | */ |
| 69 | public boolean next() throws StandardException |
| 70 | { |
| 71 | throw StandardException.newException( |
| 72 | SQLState.SORT_IMPROPER_SCAN_METHOD); |
| 73 | } |
| 74 | |
| 75 | /* Private/Protected methods of This class: */ |
| 76 | /* Public Methods of This class: */ |
| 77 | /* Public Methods of RowSource class: */ |
| 78 | |
| 79 | |
| 80 | public DataValueDescriptor[] getNextRowFromRowSource() |
| 81 | throws StandardException |
| 82 | { |
| 83 | DataValueDescriptor[] row = sortBuffer.removeFirst(); |
| 84 | |
| 85 | if (row != null) |
| 86 | { |
| 87 | mergeARow(sortBuffer.getLastAux()); |
| 88 | } |
| 89 | |
| 90 | return row; |
| 91 | } |
| 92 | |
| 93 | /** |
| 94 | * @see RowLocationRetRowSource#needsRowLocation |
| 95 | */ |
| 96 | public boolean needsRowLocation() |
| 97 | { |
| 98 | return false; |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * @see org.apache.derby.iapi.store.access.RowSource#needsToClone |
| 103 | */ |
| 104 | public boolean needsToClone() |
| 105 | { |
| 106 | return false; |
| 107 | } |
| 108 | |
| 109 | |
| 110 | /** |
| 111 | * @see RowLocationRetRowSource#rowLocation |
| 112 | */ |
| 113 | public void rowLocation(RowLocation rl) |
| 114 | { |
| 115 | if (SanityManager.DEBUG) |
| 116 | SanityManager.THROWASSERT("unexpected call to RowSource.rowLocation"); |
| 117 | } |
| 118 | |
| 119 | |
| 120 | /** |
| 121 | All columns are always set from a sorter |
| 122 | */ |
| 123 | public FormatableBitSet getValidColumns() |
| 124 | { |
| 125 | return null; |
| 126 | } |
| 127 | |
| 128 | /** |
| 129 | Close the row source - implemented by MergeScan already |
| 130 | */ |
| 131 | public void closeRowSource() |
| 132 | { |
| 133 | close(); |
| 134 | } |
| 135 | |
| 136 | } |
| 137 | |