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
- ClientTargetCollection.cs
- RowToFieldTransformer.cs
- FloatUtil.cs
- ChangeBlockUndoRecord.cs
- TextSelectionHighlightLayer.cs
- FormView.cs
- ToolboxCategoryItems.cs
- FilterableAttribute.cs
- TriggerCollection.cs
- StateDesigner.CommentLayoutGlyph.cs
- Variable.cs
- RemotingAttributes.cs
- TraceHandlerErrorFormatter.cs
- DelimitedListTraceListener.cs
- DataColumn.cs
- ExpressionBuilderContext.cs
- InfoCardRSAPKCS1KeyExchangeDeformatter.cs
- TypeConverterHelper.cs
- PeerCollaboration.cs
- DataGridViewCellMouseEventArgs.cs
- CFStream.cs
- PropertyInfoSet.cs
- PersistenceProviderFactory.cs
- RelatedCurrencyManager.cs
- ClientApiGenerator.cs
- TagNameToTypeMapper.cs
- ExtenderProvidedPropertyAttribute.cs
- XNameConverter.cs
- WebPartConnection.cs
- HasActivatableWorkflowEvent.cs
- MatrixTransform.cs
- OutputCacheProfileCollection.cs
- SecurityTokenProvider.cs
- ArglessEventHandlerProxy.cs
- RepeatButtonAutomationPeer.cs
- ProviderBase.cs
- OutputCacheSection.cs
- StyleCollection.cs
- FontStyles.cs
- SQLDouble.cs
- EngineSiteSapi.cs
- InputBinder.cs
- StringCollectionEditor.cs
- NativeMethods.cs
- SessionSwitchEventArgs.cs
- TreeNodeConverter.cs
- Transactions.cs
- RegexInterpreter.cs
- CompositeCollection.cs
- SelectorAutomationPeer.cs
- DataGridViewLinkCell.cs
- ReflectionTypeLoadException.cs
- SoapEnumAttribute.cs
- XmlCharType.cs
- SuppressMessageAttribute.cs
- InputLanguageSource.cs
- ValueUtilsSmi.cs
- Brushes.cs
- SizeChangedEventArgs.cs
- AssemblySettingAttributes.cs
- BadImageFormatException.cs
- GeometryModel3D.cs
- Keywords.cs
- DataObjectCopyingEventArgs.cs
- QueryableFilterUserControl.cs
- ComplusTypeValidator.cs
- UIPropertyMetadata.cs
- OdbcConnectionHandle.cs
- ToolboxCategoryItems.cs
- TextTreeTextNode.cs
- TaskExceptionHolder.cs
- ISFTagAndGuidCache.cs
- InstanceDataCollectionCollection.cs
- AssemblyInfo.cs
- TreeNode.cs
- FacetValueContainer.cs
- CommandDevice.cs
- Int16AnimationBase.cs
- Label.cs
- WindowPattern.cs
- ObjectPersistData.cs
- XPathQilFactory.cs
- JournalNavigationScope.cs
- _ConnectionGroup.cs
- DataTableReader.cs
- SqlMultiplexer.cs
- OdbcDataReader.cs
- CollectionViewGroupRoot.cs
- ContentTextAutomationPeer.cs
- Crc32Helper.cs
- mansign.cs
- DataStreams.cs
- Atom10FormatterFactory.cs
- SqlReferenceCollection.cs
- AssemblyNameProxy.cs
- MetaForeignKeyColumn.cs
- Control.cs
- XmlArrayItemAttribute.cs
- TrackingMemoryStreamFactory.cs
- ProcessInputEventArgs.cs