mirror of
https://github.com/MichaelGrafnetter/DSInternals
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545 lines
20 KiB
C#
545 lines
20 KiB
C#
// ---------------------------------------------------------------------------
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// <copyright file="IndexDefinition.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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// ---------------------------------------------------------------------------
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// ---------------------------------------------------------------------
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// <summary>
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// </summary>
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// ---------------------------------------------------------------------
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namespace Microsoft.Database.Isam
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{
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using System;
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using System.Globalization;
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using System.Text;
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using Microsoft.Isam.Esent.Interop;
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using Microsoft.Isam.Esent.Interop.Vista;
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/// <summary>
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/// An Index Definition contains the schema for a single index. It can be
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/// used to explore the schema for an existing index and to create the
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/// definition for a new index.
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/// </summary>
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public class IndexDefinition
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{
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/// <summary>
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/// The name
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/// </summary>
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private string name;
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/// <summary>
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/// The flags
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/// </summary>
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private IndexFlags flags = IndexFlags.None;
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/// <summary>
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/// The density
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/// </summary>
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private int density = 100;
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/// <summary>
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/// The culture information
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/// </summary>
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private CultureInfo cultureInfo = new CultureInfo("en-us");
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/// <summary>
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/// The compare options
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/// </summary>
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private CompareOptions compareOptions = CompareOptions.None;
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/// <summary>
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/// The maximum key length
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/// </summary>
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private int maxKeyLength = 256; // force new index semantics in ESENT (don't truncate source data to max key length prior to normalization)
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/// <summary>
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/// The key column collection
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/// </summary>
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private KeyColumnCollection keyColumnCollection;
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/// <summary>
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/// The conditional column collection
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/// </summary>
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private ConditionalColumnCollection conditionalColumnCollection;
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/// <summary>
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/// The read only
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/// </summary>
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private bool readOnly = false;
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/// <summary>
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/// Initializes a new instance of the <see cref="IndexDefinition"/> class.
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/// For use when defining a new index.
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/// </summary>
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/// <param name="name">
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/// The name of the index to be defined.
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/// </param>
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public IndexDefinition(string name)
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{
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this.name = name;
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this.keyColumnCollection = new KeyColumnCollection();
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this.conditionalColumnCollection = new ConditionalColumnCollection();
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="IndexDefinition"/> class.
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/// </summary>
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internal IndexDefinition()
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{
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}
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/// <summary>
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/// Gets the name of the index.
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/// </summary>
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public string Name
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{
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get
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{
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return this.name;
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}
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}
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/// <summary>
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/// Gets or sets the index's flags.
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/// </summary>
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public IndexFlags Flags
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{
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get
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{
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return this.flags;
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}
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set
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{
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this.CheckReadOnly();
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this.flags = value;
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}
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}
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/// <summary>
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/// Gets or sets the ideal density of the index in percent.
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/// </summary>
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/// <remarks>
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/// The ideal density of an index is used to setup a newly created
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/// index into a layout on disk that is appropriate for the typical
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/// workload on that index. For example, an index that will always be
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/// appended should have a density of 100% and an index that will
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/// experience random insertion should have a lower density to reflect
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/// the average density on which that index would converge at run time.
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/// <para>
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/// The density is primarily tweaked for performance reasons.
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/// </para>
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/// </remarks>
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public int Density
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{
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get
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{
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return this.density;
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}
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set
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{
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this.CheckReadOnly();
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this.density = value;
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}
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}
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/// <summary>
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/// Gets or sets the locale of the index.
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/// </summary>
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/// <remarks>
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/// A locale can be specified for any index but will only affect
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/// indexes with key columns containing string data.
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/// </remarks>
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public CultureInfo CultureInfo
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{
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get
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{
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return this.cultureInfo;
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}
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set
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{
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this.CheckReadOnly();
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this.cultureInfo = value;
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}
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}
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/// <summary>
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/// Gets or sets the locale sensitive collation options for the index.
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/// </summary>
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/// <remarks>
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/// These options can be specified for any index but will only affect
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/// indexes with key columns containing string data.
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/// </remarks>
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public CompareOptions CompareOptions
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{
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get
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{
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return this.compareOptions;
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}
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set
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{
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this.CheckReadOnly();
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this.compareOptions = value;
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}
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}
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/// <summary>
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/// Gets or sets the maximum length of a normalized key that will be stored in the
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/// index in bytes.
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/// </summary>
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/// <remarks>
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/// In many ways, this is one of the most critical parameters of an
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/// index. Key truncation can cause different records to end up with
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/// the same key which makes them indistinguishable to the index. This
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/// can cause records to be ordered randomly with respect to each other
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/// according to the index's sort order. This can also cause otherwise
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/// unique index entries to be considered duplicates which can cause
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/// some updates to fail.
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/// <para>
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/// The current limits for the ISAM are as follows: databases with 2KB
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/// pages can have keys up to 255B in length; databases with 4KB pages
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/// can have keys up to 1000B in length; and databases with 8KB pages
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/// can have keys up to 2000B in length. Note that these lengths are
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/// for normalized keys not raw key data. Normalized keys are always
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/// slightly longer than the raw data from which they are derived.
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/// </para>
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/// <para>
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/// NOTE: a max key length of 255 is "special" in that it uses legacy
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/// semantics for building keys. Those semantics include the truncation
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/// of the source data for normalization at 256 bytes. This mode should
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/// only be used if you specifically want this behavior for backwards
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/// compatibility because it causes errors during the generation of
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/// index keys under certain conditions.
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/// </para>
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/// </remarks>
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public int MaxKeyLength
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{
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get
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{
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return this.maxKeyLength;
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}
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set
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{
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this.CheckReadOnly();
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this.maxKeyLength = value;
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}
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}
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/// <summary>
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/// Gets a collection of the key columns in this index.
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/// </summary>
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public KeyColumnCollection KeyColumns
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{
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get
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{
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return this.keyColumnCollection;
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}
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}
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/// <summary>
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/// Gets a collection of conditional columns in this index.
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/// </summary>
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public ConditionalColumnCollection ConditionalColumns
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{
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get
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{
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return this.conditionalColumnCollection;
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}
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}
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/// <summary>
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/// Gets a value indicating whether this index definition cannot be changed
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/// </summary>
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/// <value>
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/// <c>true</c> if [is read only]; otherwise, <c>false</c>.
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/// </value>
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public bool IsReadOnly
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{
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get
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{
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return this.readOnly;
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}
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}
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/// <summary>
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/// Sets a value indicating whether [read only].
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/// </summary>
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/// <value>
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/// <c>true</c> if [read only]; otherwise, <c>false</c>.
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/// </value>
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internal bool ReadOnly
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{
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set
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{
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this.readOnly = value;
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}
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}
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/// <summary>
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/// Creates an <see cref="IndexDefinition"/> object from the specified <paramref name="indexList"/>.
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/// </summary>
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/// <param name="database">The database.</param>
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/// <param name="tableName">Name of the table.</param>
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/// <param name="indexList">The index list.</param>
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/// <returns>An <see cref="IndexDefinition"/> object represting the specified index.</returns>
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internal static IndexDefinition Load(IsamDatabase database, string tableName, JET_INDEXLIST indexList)
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{
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lock (database.IsamSession)
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{
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JET_SESID sesid = database.IsamSession.Sesid;
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using (IsamTransaction trx = new IsamTransaction(database.IsamSession))
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{
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// load info for the index
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IndexDefinition indexDefinition = new IndexDefinition();
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indexDefinition.name = Api.RetrieveColumnAsString(
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sesid,
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indexList.tableid,
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indexList.columnidindexname);
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CreateIndexGrbit grbitIndex = (CreateIndexGrbit)Api.RetrieveColumnAsUInt32(sesid, indexList.tableid, indexList.columnidgrbitIndex);
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indexDefinition.flags = IndexFlagsFromGrbits(grbitIndex);
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Api.JetGetIndexInfo(
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sesid,
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database.Dbid,
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tableName,
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indexDefinition.name,
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out indexDefinition.density,
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JET_IdxInfo.SpaceAlloc);
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int lcid;
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Api.JetGetIndexInfo(
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database.IsamSession.Sesid,
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database.Dbid,
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tableName,
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indexDefinition.name,
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out lcid,
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JET_IdxInfo.LCID);
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indexDefinition.cultureInfo = new CultureInfo(lcid);
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indexDefinition.compareOptions =
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Conversions.CompareOptionsFromLCMapFlags(
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Api.RetrieveColumnAsUInt32(
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database.IsamSession.Sesid,
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indexList.tableid,
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indexList.columnidLCMapFlags).GetValueOrDefault());
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// CONSIDER: move this workaround into Isam.Interop
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try
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{
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ushort maxKeyLength;
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Api.JetGetIndexInfo(
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database.IsamSession.Sesid,
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database.Dbid,
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tableName,
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indexDefinition.name,
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out maxKeyLength,
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JET_IdxInfo.KeyMost);
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indexDefinition.maxKeyLength = maxKeyLength;
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}
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catch (EsentInvalidParameterException)
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{
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indexDefinition.maxKeyLength = 255;
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}
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catch (EsentColumnNotFoundException)
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{
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indexDefinition.maxKeyLength = 255;
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}
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// load info for each key column in the index
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int currentColumn = 0;
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int totalNumberColumns = Api.RetrieveColumnAsInt32(sesid, indexList.tableid, indexList.columnidcColumn).GetValueOrDefault();
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indexDefinition.keyColumnCollection = new KeyColumnCollection();
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do
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{
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// load info for this key column
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IndexKeyGrbit grbitColumn = (IndexKeyGrbit)Api.RetrieveColumnAsUInt32(sesid, indexList.tableid, indexList.columnidgrbitColumn);
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bool isAscending = (grbitColumn & IndexKeyGrbit.Descending) == 0;
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string columnName = Api.RetrieveColumnAsString(
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sesid,
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indexList.tableid,
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indexList.columnidcolumnname);
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JET_COLUMNBASE columnbase;
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Api.JetGetColumnInfo(sesid, database.Dbid, tableName, columnName, out columnbase);
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indexDefinition.keyColumnCollection.Add(new KeyColumn(new Columnid(columnbase), isAscending));
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// move onto the next key column definition, unless it is
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// the last key column
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if (currentColumn != totalNumberColumns - 1)
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{
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Api.TryMoveNext(sesid, indexList.tableid);
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}
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}
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while (++currentColumn < totalNumberColumns);
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indexDefinition.keyColumnCollection.ReadOnly = true;
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// Vista: There is currently no efficient means to retrieve the
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// conditional columns for an index from JET. so, we are
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// going to reach into the catalog and fetch them directly.
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//
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// FUTURE: Windows 7 introduced Windows7IdxInfo.CreateIndex and Windows7IdxInfo.CreateIndex2 (and
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// Win8 has Windows8IdxInfo.CreateIndex3). Consider retrieving the conditional columns with that
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// API and converting the results. But that does not solve the problem for Vista.
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indexDefinition.conditionalColumnCollection = new ConditionalColumnCollection();
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JET_TABLEID tableidCatalog;
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Api.JetOpenTable(
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database.IsamSession.Sesid,
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database.Dbid,
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"MSysObjects",
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null,
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0,
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OpenTableGrbit.ReadOnly,
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out tableidCatalog);
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Api.JetSetCurrentIndex(sesid, tableidCatalog, "RootObjects");
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Api.MakeKey(sesid, tableidCatalog, true, MakeKeyGrbit.NewKey);
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Api.MakeKey(sesid, tableidCatalog, tableName, Encoding.ASCII, MakeKeyGrbit.None);
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Api.JetSeek(sesid, tableidCatalog, SeekGrbit.SeekEQ);
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JET_COLUMNID columnidTemp = Api.GetTableColumnid(sesid, tableidCatalog, "ObjidTable");
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int objidTable = Api.RetrieveColumnAsInt32(sesid, tableidCatalog, columnidTemp).GetValueOrDefault();
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Api.JetSetCurrentIndex(sesid, tableidCatalog, "Name");
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Api.MakeKey(sesid, tableidCatalog, objidTable, MakeKeyGrbit.NewKey);
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Api.MakeKey(sesid, tableidCatalog, (short)3, MakeKeyGrbit.None);
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Api.MakeKey(sesid, tableidCatalog, indexDefinition.name, Encoding.ASCII, MakeKeyGrbit.None);
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Api.JetSeek(sesid, tableidCatalog, SeekGrbit.SeekEQ);
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columnidTemp = Api.GetTableColumnid(sesid, tableidCatalog, "Flags");
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int indexFlagsBytes = Api.RetrieveColumnAsInt32(sesid, tableidCatalog, columnidTemp).GetValueOrDefault();
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columnidTemp = Api.GetTableColumnid(sesid, tableidCatalog, "ConditionalColumns");
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byte[] conditionalColumnsBytes = Api.RetrieveColumn(sesid, tableidCatalog, columnidTemp);
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for (int ib = 0; conditionalColumnsBytes != null && ib < conditionalColumnsBytes.Length; ib += 4)
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{
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uint colid;
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bool mustBeNull;
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JET_COLUMNBASE columnBase;
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// fIDXExtendedColumns
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if ((indexFlagsBytes & 0xffff0000) == 0x00010000)
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{
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// fIDXSEGTemplateColumn
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if ((conditionalColumnsBytes[ib + 0] & 0x80) != 0)
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{
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// fCOLUMNIDTemplate
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colid = 0x80000000 | (uint)(conditionalColumnsBytes[ib + 3] << 8) | (uint)conditionalColumnsBytes[ib + 2];
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}
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else
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{
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colid = (uint)(conditionalColumnsBytes[ib + 3] << 8) | (uint)conditionalColumnsBytes[ib + 2];
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}
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// fIDXSEGMustBeNull
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if ((conditionalColumnsBytes[ib + 0] & 0x20) != 0)
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{
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mustBeNull = true;
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}
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else
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{
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mustBeNull = false;
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}
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}
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else
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{
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// do not load conditional columns from an unknown format
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continue;
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}
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JET_COLUMNID castedColid = JET_COLUMNID.CreateColumnidFromNativeValue(unchecked((int)colid));
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VistaApi.JetGetColumnInfo(
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database.IsamSession.Sesid,
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database.Dbid,
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tableName,
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castedColid,
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out columnBase);
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indexDefinition.conditionalColumnCollection.Add(new ConditionalColumn(new Columnid(columnBase), mustBeNull));
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}
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indexDefinition.conditionalColumnCollection.ReadOnly = true;
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indexDefinition.ReadOnly = true;
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return indexDefinition;
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}
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}
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}
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/// <summary>
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/// Converts the <see cref="CreateIndexGrbit"/> enumeration to <see cref="IndexFlags"/>.
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/// </summary>
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/// <param name="grbitIndex">Index of the grbit.</param>
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/// <returns>The <see cref="IndexFlags"/> equivalent to <paramref name="grbitIndex"/>.</returns>
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private static IndexFlags IndexFlagsFromGrbits(CreateIndexGrbit grbitIndex)
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{
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IndexFlags flags = IndexFlags.None;
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if ((grbitIndex & CreateIndexGrbit.IndexUnique) != 0)
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{
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flags = flags | IndexFlags.Unique;
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}
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if ((grbitIndex & CreateIndexGrbit.IndexPrimary) != 0)
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{
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flags = flags | IndexFlags.Primary;
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}
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if ((grbitIndex & CreateIndexGrbit.IndexDisallowNull) != 0)
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{
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flags = flags | IndexFlags.DisallowNull;
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}
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if ((grbitIndex & CreateIndexGrbit.IndexIgnoreNull) != 0)
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{
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flags = flags | IndexFlags.IgnoreNull;
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}
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if ((grbitIndex & CreateIndexGrbit.IndexIgnoreAnyNull) != 0)
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{
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flags = flags | IndexFlags.IgnoreAnyNull;
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}
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if ((grbitIndex & CreateIndexGrbit.IndexSortNullsHigh) != 0)
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{
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flags = flags | IndexFlags.SortNullsHigh;
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}
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if ((grbitIndex & VistaGrbits.IndexDisallowTruncation) != 0)
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{
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flags = flags | IndexFlags.DisallowTruncation;
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}
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else
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{
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flags = flags | IndexFlags.AllowTruncation;
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}
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return flags;
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}
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/// <summary>
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/// Checks the read only.
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/// </summary>
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/// <exception cref="System.NotSupportedException">this index definition cannot be changed</exception>
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private void CheckReadOnly()
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{
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if (this.readOnly)
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{
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throw new NotSupportedException("this index definition cannot be changed");
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}
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}
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}
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}
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