docstring

James Cor · James Cor · commit a49d4f051c26 · 2024-10-24T16:33:04.000-07:00
diff --git a/sql/planbuilder/factory.go b/sql/planbuilder/factory.go
@@ -178,6 +178,12 @@ func (f *factory) buildTableAlias(name string, child sql.Node) (plan.TableIdNode
 	}
 }
 
+
+// buildDistinct will wrap the child node in a distinct node depending on the Sort nodes and Projections there.
+// if the sort fields are a subset of the projection fields
+//    sort(project(table)) -> sort(distinct(project(table)))
+// else
+//    sort(project(table)) -> distinct(sort(project(table)))
 func (f *factory) buildDistinct(child sql.Node) sql.Node {
 	if proj, isProj := child.(*plan.Project); isProj {
 		// TODO: if projection columns are just primary key, distinct is no-op

Original file line number	Diff line number	Diff line change
`@@ -178,6 +178,12 @@ func (f *factory) buildTableAlias(name string, child sql.Node) (plan.TableIdNode`
`178`	`178`	`}`
`179`	`179`	`}`
`180`	`180`
	`181`	`+`
	`182`	`+// buildDistinct will wrap the child node in a distinct node depending on the Sort nodes and Projections there.`
	`183`	`+// if the sort fields are a subset of the projection fields`
	`184`	`+// sort(project(table)) -> sort(distinct(project(table)))`
	`185`	`+// else`
	`186`	`+// sort(project(table)) -> distinct(sort(project(table)))`
`181`	`187`	`func (f *factory) buildDistinct(child sql.Node) sql.Node {`
`182`	`188`	`if proj, isProj := child.(*plan.Project); isProj {`
`183`	`189`	`// TODO: if projection columns are just primary key, distinct is no-op`