本文整理汇总了C#中System.Data.Query.InternalTrees.Command.GetExtendedNodeInfo方法的典型用法代码示例。如果您正苦于以下问题：C# Command.GetExtendedNodeInfo方法的具体用法？C# Command.GetExtendedNodeInfo怎么用？C# Command.GetExtendedNodeInfo使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类System.Data.Query.InternalTrees.Command的用法示例。
在下文中一共展示了Command.GetExtendedNodeInfo方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C#代码示例。
示例1: GetPushdownPredicate
/// <summary>
/// Split up a predicate into 2 parts - the pushdown and the non-pushdown predicate.
///
/// If the filter node has no external references *and* the "columns" parameter is null,
/// then the entire predicate can be pushed down
///
/// We then compute the set of valid column references - if the "columns" parameter
/// is non-null, this set is used. Otherwise, we get the definitions of the
/// input relop node of the filterOp, and use that.
///
/// We use this list of valid column references to identify which parts of the filter
/// predicate can be pushed down - only those parts of the predicate that do not
/// reference anything beyond these columns are considered for pushdown. The rest are
/// stuffed into the nonPushdownPredicate output parameter
///
/// </summary>
/// <param name="command">Command object</param>
/// <param name="filterNode">the FilterOp subtree</param>
/// <param name="columns">(Optional) List of columns to consider for "pushdown"</param>
/// <param name="nonPushdownPredicateNode">(output) Part of the predicate that cannot be pushed down</param>
/// <returns>part of the predicate that can be pushed down</returns>
private static Node GetPushdownPredicate(Command command, Node filterNode, VarVec columns, out Node nonPushdownPredicateNode)
{
var pushdownPredicateNode = filterNode.Child1;
nonPushdownPredicateNode = null;
var filterNodeInfo = command.GetExtendedNodeInfo(filterNode);
if (columns == null
&& filterNodeInfo.ExternalReferences.IsEmpty)
{
return pushdownPredicateNode;
}
if (columns == null)
{
var inputNodeInfo = command.GetExtendedNodeInfo(filterNode.Child0);
columns = inputNodeInfo.Definitions;
}
var predicate = new Predicate(command, pushdownPredicateNode);
Predicate nonPushdownPredicate;
predicate = predicate.GetSingleTablePredicates(columns, out nonPushdownPredicate);
pushdownPredicateNode = predicate.BuildAndTree();
nonPushdownPredicateNode = nonPushdownPredicate.BuildAndTree();
return pushdownPredicateNode;
}