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  • Oracle 随笔

    1.位图索引适合低基数(low cardinality)列,该列只有有限个可取值,但是更新或插入位图索引键会将这个键所对应的所有记录和要更新的那条记录一同锁定,从而降低了并发性。对应此问题可以在该列创建B*Tree索引,可以只对感兴趣的值创建索引。

    2.Property and Attribute

    Property是本质上是一对get,set方法,可以进行访问控制 翻译为属性;

    Attribute是特性,是对程序集、类、方法、属性等对象的描述信息,特性提供的信息也称为元数据,可以通过反射的方式获取特性信息

            AnimalTypeTestClass testClass = new AnimalTypeTestClass();
    Type type
    = testClass.GetType();
    // Iterate through all the methods of the class.
    foreach(MethodInfo mInfo in type.GetMethods()) 
          {
    // Iterate through all the Attributes for each method.
    foreach (Attribute attr in
    Attribute.GetCustomAttributes(mInfo)) 
             {
    // Check for the AnimalType attribute.
    if (attr.GetType() == typeof(AnimalTypeAttribute))
    Console.WriteLine(
    "Method {0} has a pet {1} attribute.",
    mInfo.Name, ((AnimalTypeAttribute)attr).Pet);
    }

    }

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  • 原文地址:https://www.cnblogs.com/asingna/p/1978573.html
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