From c595ef68c7ce266d44ecf27b949c497b345e48c4 Mon Sep 17 00:00:00 2001
From: Tobias Schottdorf <tobias.schottdorf@gmail.com>
Date: Mon, 14 Mar 2016 18:27:59 -0400
Subject: [PATCH] Use more efficient query

See https://github.com/cockroachdb/cockroach/issues/4925#issuecomment-196513251
---
 photos/db.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/photos/db.go b/photos/db.go
index 703d0b8..3018a56 100644
--- a/photos/db.go
+++ b/photos/db.go
@@ -315,8 +315,10 @@ func listComments(tx *sql.Tx, userID int, commentIDs *[][]byte) ([]byte, error)
 	if err != nil {
 		return nil, err
 	}
-	const selectSQL = `
-SELECT commentID, userID, message, timestamp FROM comments WHERE photoID = $1 ORDER BY timestamp DESC LIMIT 100`
+	const selectSQL = `SELECT commentID, userID, message, timestamp FROM comments ` +
+		`WHERE photoID = $1 AND commentID IN ` +
+		`(SELECT commentID FROM comments WHERE photoID = $1 ORDER BY timestamp DESC LIMIT 100)` +
+		`ORDER BY timestamp DESC`
 	rows, err := tx.Query(selectSQL, photoID)
 	switch {
 	case err == sql.ErrNoRows: