diff --git a/docs/benchmarks.md b/docs/benchmarks.md
index 1712f81..a4e9203 100644
--- a/docs/benchmarks.md
+++ b/docs/benchmarks.md
@@ -625,6 +625,12 @@ to dimensions, and the selective-dimension-join pattern. Those are a large part
 what columnar storage is usually bought for, and this page says nothing about
 them. Not that we do badly on them. We have not measured them. See #401.
 
+Joins themselves work. A columnar table joins a heap table in either direction,
+and joins another columnar table. Hash, merge and nested-loop strategies all return
+the same rows as the all-heap equivalent. Column projection survives the join, so
+the columnar side reads only the columns the join and the target list need. What is
+absent is a measurement of how fast that is, not evidence that it works.
+
 Read the conclusions below as being about single-table scan and aggregate work,
 because that is the evidence behind them.