From ad6d4b574055ea16bc9c28c76ba6d12d7a1dc88a Mon Sep 17 00:00:00 2001
From: Ryan Leckey <ryan@launchbadge.com>
Date: Fri, 29 Jan 2021 23:37:29 -0800
Subject: [PATCH] perf(mysql): guarantee no allocation if no columns are passed
 to Row::deserialize_with

---
 sqlx-mysql/src/protocol/row.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sqlx-mysql/src/protocol/row.rs b/sqlx-mysql/src/protocol/row.rs
index 429315a3..b3df07bf 100644
--- a/sqlx-mysql/src/protocol/row.rs
+++ b/sqlx-mysql/src/protocol/row.rs
@@ -12,6 +12,10 @@ pub(crate) struct Row {
 
 impl<'de> Deserialize<'de, &'de [ColumnDefinition]> for Row {
     fn deserialize_with(mut buf: Bytes, columns: &'de [ColumnDefinition]) -> Result<Self> {
+        if columns.is_empty() {
+            return Ok(Self { values: vec![] });
+        }
+
         let mut values = Vec::with_capacity(columns.len());
 
         for _ in columns {