Code:
/ Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / DEVDIV / depot / DevDiv / releases / Orcas / NetFXw7 / ndp / fx / src / DataEntity / System / Data / Map / ViewGeneration / QueryRewriting / RewritingSimplifier.cs / 1 / RewritingSimplifier.cs
using System; using System.Diagnostics; using System.Collections.Generic; using System.Text; using System.Linq; namespace System.Data.Mapping.ViewGeneration.QueryRewriting { internal class RewritingSimplifierwhere T_Tile : class { private readonly T_Tile m_originalRewriting; private readonly T_Tile m_toAvoid; private readonly RewritingProcessor m_qp; private readonly Dictionary m_usedViews = new Dictionary (); // used for join/antisemijoin simplification private RewritingSimplifier(T_Tile originalRewriting, T_Tile toAvoid, Dictionary usedViews, RewritingProcessor qp) { m_originalRewriting = originalRewriting; m_toAvoid = toAvoid; m_qp = qp; m_usedViews = usedViews; } // used for union simplification private RewritingSimplifier(T_Tile rewriting, T_Tile toFill, T_Tile toAvoid, RewritingProcessor qp) { m_originalRewriting = toFill; m_toAvoid = toAvoid; m_qp = qp; m_usedViews = new Dictionary (); GatherUnionedSubqueriesInUsedViews(rewriting); } // called for top query only internal static bool TrySimplifyUnionRewriting(ref T_Tile rewriting, T_Tile toFill, T_Tile toAvoid, RewritingProcessor qp) { RewritingSimplifier simplifier = new RewritingSimplifier (rewriting, toFill, toAvoid, qp); // gather all unioned subqueries T_Tile simplifiedRewriting; if (simplifier.SimplifyRewriting(out simplifiedRewriting)) { rewriting = simplifiedRewriting; return true; } return false; } // modifies usedViews - removes all redundant views from it internal static bool TrySimplifyJoinRewriting(ref T_Tile rewriting, T_Tile toAvoid, Dictionary usedViews, RewritingProcessor qp) { RewritingSimplifier simplifier = new RewritingSimplifier (rewriting, toAvoid, usedViews, qp); T_Tile simplifiedRewriting; if (simplifier.SimplifyRewriting(out simplifiedRewriting)) { rewriting = simplifiedRewriting; return true; } return false; } private void GatherUnionedSubqueriesInUsedViews(T_Tile query) { if (query != null) { if (m_qp.GetOpKind(query) != TileOpKind.Union) { m_usedViews[query] = TileOpKind.Union; } else { GatherUnionedSubqueriesInUsedViews(m_qp.GetArg1(query)); GatherUnionedSubqueriesInUsedViews(m_qp.GetArg2(query)); } } } // isExactAnswer: matters for Intersections/Differences only private bool SimplifyRewriting(out T_Tile simplifiedRewriting) { bool compacted = false; simplifiedRewriting = null; T_Tile simplifiedOnce; while (SimplifyRewritingOnce(out simplifiedOnce)) { compacted = true; simplifiedRewriting = simplifiedOnce; } return compacted; } // try removing one redundant view from intersected and subtracted views // This method uses a dynamic divide-and-conquer algorithm that avoids recomputing many intersections/differences private bool SimplifyRewritingOnce(out T_Tile simplifiedRewriting) { // check whether removing one or multiple views from intersected and subtracted views // still (a) reduces extra tuples, and (b) has no missing tuples // First, try removing a subtracted view HashSet remainingViews = new HashSet (m_usedViews.Keys); foreach (T_Tile usedView in m_usedViews.Keys) { // pick an intersected view, and nail it down switch (m_usedViews[usedView]) { case TileOpKind.Join: case TileOpKind.Union: remainingViews.Remove(usedView); if (SimplifyRewritingOnce(usedView, remainingViews, out simplifiedRewriting)) { return true; } remainingViews.Add(usedView); break; } } simplifiedRewriting = null; return false; } // remainingViews may contain either unions only or intersections + differences private bool SimplifyRewritingOnce(T_Tile newRewriting, HashSet remainingViews, out T_Tile simplifiedRewriting) { simplifiedRewriting = null; if (remainingViews.Count == 0) { return false; } if (remainingViews.Count == 1) { // determine the remaining view T_Tile remainingView = remainingViews.First(); // check whether rewriting obtained so far is good enough // try disposing of this remaining view bool isDisposable = false; switch (m_usedViews[remainingView]) { case TileOpKind.Union: // check whether rewriting still covers toFill isDisposable = m_qp.IsContainedIn(m_originalRewriting, newRewriting); break; default: // intersection isDisposable = m_qp.IsContainedIn(m_originalRewriting, newRewriting) && m_qp.IsDisjointFrom(m_toAvoid, newRewriting); break; } if (isDisposable) { // yes, the remaining view is disposable simplifiedRewriting = newRewriting; m_usedViews.Remove(remainingView); return true; } return false; // no, can't trash the remaining view } // split remainingViews into two halves // Compute rewriting for first half. Call recursively on second half. // Then, compute rewriting for second half. Call recursively on first half. int halfCount = remainingViews.Count / 2; int count = 0; T_Tile firstHalfRewriting = newRewriting; T_Tile secondHalfRewriting = newRewriting; HashSet firstHalf = new HashSet (); HashSet secondHalf = new HashSet (); foreach (T_Tile remainingView in remainingViews) { TileOpKind viewKind = m_usedViews[remainingView]; // add to first half if (count++ < halfCount) { firstHalf.Add(remainingView); firstHalfRewriting = GetRewritingHalf(firstHalfRewriting, remainingView, viewKind); } else // add to second half { secondHalf.Add(remainingView); secondHalfRewriting = GetRewritingHalf(secondHalfRewriting, remainingView, viewKind); } } // now, call recursively return SimplifyRewritingOnce(firstHalfRewriting, secondHalf, out simplifiedRewriting) || SimplifyRewritingOnce(secondHalfRewriting, firstHalf, out simplifiedRewriting); } private T_Tile GetRewritingHalf(T_Tile halfRewriting, T_Tile remainingView, TileOpKind viewKind) { switch (viewKind) { case TileOpKind.Join: halfRewriting = m_qp.Join(halfRewriting, remainingView); break; case TileOpKind.AntiSemiJoin: halfRewriting = m_qp.AntiSemiJoin(halfRewriting, remainingView); break; case TileOpKind.Union: halfRewriting = m_qp.Union(halfRewriting, remainingView); break; default: Debug.Fail("unexpected"); break; } return halfRewriting; } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved. using System; using System.Diagnostics; using System.Collections.Generic; using System.Text; using System.Linq; namespace System.Data.Mapping.ViewGeneration.QueryRewriting { internal class RewritingSimplifier where T_Tile : class { private readonly T_Tile m_originalRewriting; private readonly T_Tile m_toAvoid; private readonly RewritingProcessor m_qp; private readonly Dictionary m_usedViews = new Dictionary (); // used for join/antisemijoin simplification private RewritingSimplifier(T_Tile originalRewriting, T_Tile toAvoid, Dictionary usedViews, RewritingProcessor qp) { m_originalRewriting = originalRewriting; m_toAvoid = toAvoid; m_qp = qp; m_usedViews = usedViews; } // used for union simplification private RewritingSimplifier(T_Tile rewriting, T_Tile toFill, T_Tile toAvoid, RewritingProcessor qp) { m_originalRewriting = toFill; m_toAvoid = toAvoid; m_qp = qp; m_usedViews = new Dictionary (); GatherUnionedSubqueriesInUsedViews(rewriting); } // called for top query only internal static bool TrySimplifyUnionRewriting(ref T_Tile rewriting, T_Tile toFill, T_Tile toAvoid, RewritingProcessor qp) { RewritingSimplifier simplifier = new RewritingSimplifier (rewriting, toFill, toAvoid, qp); // gather all unioned subqueries T_Tile simplifiedRewriting; if (simplifier.SimplifyRewriting(out simplifiedRewriting)) { rewriting = simplifiedRewriting; return true; } return false; } // modifies usedViews - removes all redundant views from it internal static bool TrySimplifyJoinRewriting(ref T_Tile rewriting, T_Tile toAvoid, Dictionary usedViews, RewritingProcessor qp) { RewritingSimplifier simplifier = new RewritingSimplifier (rewriting, toAvoid, usedViews, qp); T_Tile simplifiedRewriting; if (simplifier.SimplifyRewriting(out simplifiedRewriting)) { rewriting = simplifiedRewriting; return true; } return false; } private void GatherUnionedSubqueriesInUsedViews(T_Tile query) { if (query != null) { if (m_qp.GetOpKind(query) != TileOpKind.Union) { m_usedViews[query] = TileOpKind.Union; } else { GatherUnionedSubqueriesInUsedViews(m_qp.GetArg1(query)); GatherUnionedSubqueriesInUsedViews(m_qp.GetArg2(query)); } } } // isExactAnswer: matters for Intersections/Differences only private bool SimplifyRewriting(out T_Tile simplifiedRewriting) { bool compacted = false; simplifiedRewriting = null; T_Tile simplifiedOnce; while (SimplifyRewritingOnce(out simplifiedOnce)) { compacted = true; simplifiedRewriting = simplifiedOnce; } return compacted; } // try removing one redundant view from intersected and subtracted views // This method uses a dynamic divide-and-conquer algorithm that avoids recomputing many intersections/differences private bool SimplifyRewritingOnce(out T_Tile simplifiedRewriting) { // check whether removing one or multiple views from intersected and subtracted views // still (a) reduces extra tuples, and (b) has no missing tuples // First, try removing a subtracted view HashSet remainingViews = new HashSet (m_usedViews.Keys); foreach (T_Tile usedView in m_usedViews.Keys) { // pick an intersected view, and nail it down switch (m_usedViews[usedView]) { case TileOpKind.Join: case TileOpKind.Union: remainingViews.Remove(usedView); if (SimplifyRewritingOnce(usedView, remainingViews, out simplifiedRewriting)) { return true; } remainingViews.Add(usedView); break; } } simplifiedRewriting = null; return false; } // remainingViews may contain either unions only or intersections + differences private bool SimplifyRewritingOnce(T_Tile newRewriting, HashSet remainingViews, out T_Tile simplifiedRewriting) { simplifiedRewriting = null; if (remainingViews.Count == 0) { return false; } if (remainingViews.Count == 1) { // determine the remaining view T_Tile remainingView = remainingViews.First(); // check whether rewriting obtained so far is good enough // try disposing of this remaining view bool isDisposable = false; switch (m_usedViews[remainingView]) { case TileOpKind.Union: // check whether rewriting still covers toFill isDisposable = m_qp.IsContainedIn(m_originalRewriting, newRewriting); break; default: // intersection isDisposable = m_qp.IsContainedIn(m_originalRewriting, newRewriting) && m_qp.IsDisjointFrom(m_toAvoid, newRewriting); break; } if (isDisposable) { // yes, the remaining view is disposable simplifiedRewriting = newRewriting; m_usedViews.Remove(remainingView); return true; } return false; // no, can't trash the remaining view } // split remainingViews into two halves // Compute rewriting for first half. Call recursively on second half. // Then, compute rewriting for second half. Call recursively on first half. int halfCount = remainingViews.Count / 2; int count = 0; T_Tile firstHalfRewriting = newRewriting; T_Tile secondHalfRewriting = newRewriting; HashSet firstHalf = new HashSet (); HashSet secondHalf = new HashSet (); foreach (T_Tile remainingView in remainingViews) { TileOpKind viewKind = m_usedViews[remainingView]; // add to first half if (count++ < halfCount) { firstHalf.Add(remainingView); firstHalfRewriting = GetRewritingHalf(firstHalfRewriting, remainingView, viewKind); } else // add to second half { secondHalf.Add(remainingView); secondHalfRewriting = GetRewritingHalf(secondHalfRewriting, remainingView, viewKind); } } // now, call recursively return SimplifyRewritingOnce(firstHalfRewriting, secondHalf, out simplifiedRewriting) || SimplifyRewritingOnce(secondHalfRewriting, firstHalf, out simplifiedRewriting); } private T_Tile GetRewritingHalf(T_Tile halfRewriting, T_Tile remainingView, TileOpKind viewKind) { switch (viewKind) { case TileOpKind.Join: halfRewriting = m_qp.Join(halfRewriting, remainingView); break; case TileOpKind.AntiSemiJoin: halfRewriting = m_qp.AntiSemiJoin(halfRewriting, remainingView); break; case TileOpKind.Union: halfRewriting = m_qp.Union(halfRewriting, remainingView); break; default: Debug.Fail("unexpected"); break; } return halfRewriting; } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- SqlNotificationRequest.cs
- DocumentSequence.cs
- XmlCharCheckingWriter.cs
- XmlStreamStore.cs
- MailDefinition.cs
- DSASignatureFormatter.cs
- Form.cs
- EdgeProfileValidation.cs
- parserscommon.cs
- QueryRelOp.cs
- EventLogPermissionEntryCollection.cs
- DbParameterHelper.cs
- LambdaCompiler.cs
- PrivateUnsafeNativeCompoundFileMethods.cs
- MULTI_QI.cs
- Padding.cs
- TrackingServices.cs
- AuthorizationContext.cs
- ImageIndexConverter.cs
- MouseGestureValueSerializer.cs
- StringReader.cs
- Hash.cs
- DockProviderWrapper.cs
- FamilyTypefaceCollection.cs
- NavigationProperty.cs
- DecoderNLS.cs
- OracleDateTime.cs
- CollectionViewGroup.cs
- DiffuseMaterial.cs
- DataContractJsonSerializerOperationBehavior.cs
- HitTestWithPointDrawingContextWalker.cs
- Comparer.cs
- EventSchemaTraceListener.cs
- UrlMappingCollection.cs
- FormParameter.cs
- InstalledFontCollection.cs
- JsonReaderDelegator.cs
- SoapIgnoreAttribute.cs
- SettingsAttributeDictionary.cs
- DataGridRowDetailsEventArgs.cs
- ListItem.cs
- AnonymousIdentificationSection.cs
- SchemaMapping.cs
- Exceptions.cs
- ScaleTransform.cs
- DataGridViewHeaderCell.cs
- Boolean.cs
- CustomValidator.cs
- WorkflowRuntimeServiceElement.cs
- NameValuePermission.cs
- ThreadStartException.cs
- ByteStream.cs
- ListMarkerLine.cs
- GridViewDeletedEventArgs.cs
- ResourceExpressionEditorSheet.cs
- CodeComment.cs
- NegotiationTokenAuthenticatorState.cs
- UIElementAutomationPeer.cs
- ParentUndoUnit.cs
- MemoryRecordBuffer.cs
- AnimationException.cs
- KeyValuePair.cs
- Avt.cs
- BmpBitmapDecoder.cs
- HighlightComponent.cs
- SaveWorkflowAsyncResult.cs
- RelationshipEndCollection.cs
- AppDomainProtocolHandler.cs
- GeneralTransform3DTo2DTo3D.cs
- DataChangedEventManager.cs
- WaveHeader.cs
- ListItemConverter.cs
- RecordBuilder.cs
- EventDriven.cs
- SQlBooleanStorage.cs
- SR.cs
- EnumerationRangeValidationUtil.cs
- MimeReturn.cs
- SymbolEqualComparer.cs
- FileChangesMonitor.cs
- Iis7Helper.cs
- Soap12FormatExtensions.cs
- PageDeviceFont.cs
- EdmError.cs
- srgsitem.cs
- RootBuilder.cs
- Variant.cs
- DataTableReaderListener.cs
- TriState.cs
- _ConnectStream.cs
- ThrowOnMultipleAssignment.cs
- FontFamily.cs
- ReflectEventDescriptor.cs
- SafeUserTokenHandle.cs
- InvariantComparer.cs
- MemberPathMap.cs
- DateTimeHelper.cs
- ActivityTypeCodeDomSerializer.cs
- WindowsTab.cs
- __Filters.cs