From 96df2700fd6dd9db6e751fb391da5bc158a4de58 Mon Sep 17 00:00:00 2001
From: reesporte <reesedporter@gmail.com>
Date: Mon, 11 Apr 2022 09:34:06 -0500
Subject: [PATCH] save space when union-ing DistinctTimestamps

By using an empty struct, we reduce memory usage by
up to 16 bytes (the size of a timestamp string)
---
 executor.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/executor.go b/executor.go
index 3d9580e62..bde4830c1 100644
--- a/executor.go
+++ b/executor.go
@@ -1617,12 +1617,12 @@ func (d DistinctTimestamp) ToRows(callback func(*proto.RowResponse) error) error
 
 // Union returns the union of the values of `d` and `other`
 func (d *DistinctTimestamp) Union(other DistinctTimestamp) DistinctTimestamp {
-	both := map[string]string{}
+	both := map[string]struct{}{}
 	for _, val := range d.Values {
-		both[val] = val
+		both[val] = struct{}{}
 	}
 	for _, val := range other.Values {
-		both[val] = val
+		both[val] = struct{}{}
 	}
 	vals := []string{}
 	for key := range both {