From fa24a9ebcc95caa748a4f7ffc2ef0aa5ae299f2c Mon Sep 17 00:00:00 2001
From: Sergei Morozov <morozov@tut.by>
Date: Thu, 23 May 2019 15:03:35 -0700
Subject: [PATCH] The usage of user-provided `PDO` instance is deprecated

---
 UPGRADE.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/UPGRADE.md b/UPGRADE.md
index 329c92b226a..9639a6065a6 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,5 +1,12 @@
 # Upgrade to 2.10
 
+## Deprecated usage of user-provided `PDO` instance
+
+The usage of user-provided `PDO` instance is deprecated. The known use cases are:
+
+1. **Persistent PDO connections.** DBAL 3.0 will supported establishing persistent connections, therefore, providing a pre-created persistent PDO connection will be no longer needed.
+2. **Sharing `PDO` instance between DBAL and legacy components.** In order to share a PDO instance, initialize the connection in DBAL and access it using `Connection::getWrappedConnection()->getWrappedConnection()`.
+
 ## MINOR BC BREAK: Default values are no longer handled as SQL expressions
 
 They are converted to SQL literals (e.g. escaped). Clients must now specify default values in their initial form, not in the form of an SQL literal (e.g. escaped).