From b6e5ce549a8d17a59f86b06ebe02a84aa74f93e0 Mon Sep 17 00:00:00 2001 From: Yiding Cui Date: Mon, 18 Apr 2022 16:00:29 +0800 Subject: [PATCH] Update planner/funcdep/fd_graph.go Co-authored-by: Zhou Kunqin <25057648+time-and-fate@users.noreply.github.com> --- planner/funcdep/fd_graph.go | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/planner/funcdep/fd_graph.go b/planner/funcdep/fd_graph.go index 8cfef59cf0a5d..566febe9f22b6 100644 --- a/planner/funcdep/fd_graph.go +++ b/planner/funcdep/fd_graph.go @@ -653,7 +653,7 @@ func (s *FDSet) MakeCartesianProduct(rhs *FDSet) { // miss matched rows from left side are unique originally, even appended with NULL value from right side, they are still // strictly determine themselves and even the all rows after left join. // conclusion combined: -// equivalence with both strict Key from right and left, the left side's strict FD can be extended to all rows after left join. +// If there is an equivalence covering both strict Key from the right and left, we can create a new strict FD: {columns of the left side of the join in the equivalence} -> {all columns after join}. // // <3.3> equivalence FD: let's see equivalence FD as double-directed strict FD from join equal conditions, and we only keep the // rhs ~~> lhs.