The type of the link. For example, in Hash Joins this could be used to
distinguish between the build child and the probe child, or in the case
of the child being an output variable, to represent the tag associated
with the output variable.
Only present if the child node is [SCALAR][google.spanner.v1.PlanNode.Kind.SCALAR] and corresponds
to an output variable of the parent node. The field carries the name of
the output variable.
For example, a TableScan operator that reads rows from a table will
have child links to the SCALAR nodes representing the output variables
created for each column that is read by the operator. The corresponding
variable fields will be set to the variable names assigned to the
columns.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-07 UTC."],[[["\u003cp\u003eThis document outlines the \u003ccode\u003eChildLink\u003c/code\u003e class, a component of the \u003ccode\u003ePlanNode.Types\u003c/code\u003e within the \u003ccode\u003eGoogle.Cloud.Spanner.V1\u003c/code\u003e namespace, used to represent parent-child relationships in query plans.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eChildLink\u003c/code\u003e class implements several interfaces, including \u003ccode\u003eIMessage\u003c/code\u003e, \u003ccode\u003eIEquatable\u003c/code\u003e, \u003ccode\u003eIDeepCloneable\u003c/code\u003e, and \u003ccode\u003eIBufferMessage\u003c/code\u003e, providing functionality for message handling, equality checks, deep cloning, and buffer-based message operations.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eChildLink\u003c/code\u003e class has properties like \u003ccode\u003eChildIndex\u003c/code\u003e, \u003ccode\u003eType\u003c/code\u003e, and \u003ccode\u003eVariable\u003c/code\u003e, which store the index of the linked child node, the type of the link (e.g., "build" or "probe" in Hash Joins), and the name of an output variable, respectively.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eChildLink\u003c/code\u003e class has two constructors, a default one, and another one that takes in another instance of itself.\u003c/p\u003e\n"],["\u003cp\u003eThe page displays a list of available versions of the \u003ccode\u003ePlanNode.Types.ChildLink\u003c/code\u003e class for Google Cloud Spanner, ranging from version 3.5.0 to the latest beta release, 5.0.0-beta05.\u003c/p\u003e\n"]]],[],null,[]]
