[ci skip] Correct session database setup docs

2 files changed, 15 insertions, 7 deletions

diff --git a/application/config/config.php b/application/config/config.php
index a4d883fab..479d591a4 100644
--- a/application/config/config.php
+++ b/application/config/config.php
@@ -344,6 +344,9 @@ $config['encryption_key'] = '';
 |
 |	Whether to match the user's IP address when reading the session data.
 |
+|	WARNING: If you're using the database driver, don't forget to update
+|	         your session table's PRIMARY KEY when changing this setting.
+|
 | 'sess_time_to_update'
 |
 |	How many seconds between CI regenerating the session ID.
diff --git a/user_guide_src/source/libraries/sessions.rst b/user_guide_src/source/libraries/sessions.rst
index 2034ed2b0..9c9761bbf 100644
--- a/user_guide_src/source/libraries/sessions.rst
+++ b/user_guide_src/source/libraries/sessions.rst
@@ -598,7 +598,6 @@ For MySQL::
 		`ip_address` varchar(45) NOT NULL,
 		`timestamp` int(10) unsigned DEFAULT 0 NOT NULL,
 		`data` blob NOT NULL,
-		PRIMARY KEY (id),
 		KEY `ci_sessions_timestamp` (`timestamp`)
 	);
 
@@ -608,17 +607,23 @@ For PostgreSQL::
 		"id" varchar(40) NOT NULL,
 		"ip_address" varchar(45) NOT NULL,
 		"timestamp" bigint DEFAULT 0 NOT NULL,
-		"data" text DEFAULT '' NOT NULL,
-		PRIMARY KEY ("id")
+		"data" text DEFAULT '' NOT NULL
 	);
 
 	CREATE INDEX "ci_sessions_timestamp" ON "ci_sessions" ("timestamp");
 
-However, if you want to turn on the *sess_match_ip* setting, you should
-also do the following, after creating the table::
+You will also need to add a PRIMARY KEY **depending on your 'sess_match_ip'
+setting**. The examples below work both on MySQL and PostgreSQL::
+
+	// When sess_match_ip = TRUE
+	ALTER TABLE ci_sessions ADD PRIMARY KEY (id, ip_address);
+
+	// When sess_match_ip = FALSE
+	ALTER TABLE ci_sessions ADD PRIMARY KEY (id);
+
+	// To drop a previously created primary key (use when changing the setting)
+	ALTER TABLE ci_sessions DROP PRIMARY KEY;
 
-	// Works both on MySQL and PostgreSQL
-	ALTER TABLE ci_sessions ADD CONSTRAINT ci_sessions_id_ip UNIQUE (id, ip_address);
 
 .. important:: Only MySQL and PostgreSQL databases are officially
 	supported, due to lack of advisory locking mechanisms on other