Use Postgres type BYTEA to store session data

It's not so difficult to use after all and the type saves space
compared to base64-encoded text.

system/Session/Handlers/DatabaseHandler.php

@@ -167,7 +167,7 @@ public function read($sessionID): string
 		$this->sessionID = $sessionID;
 
 		$builder = $this->db->table($this->table)
-				->select('data')
+				->select($this->platform === 'postgre' ? "encode(data, 'base64') AS data" : 'data')
 				->where('id', $sessionID);
 
 		if ($this->matchIP)
@@ -188,9 +188,6 @@ public function read($sessionID): string
 			return '';
 		}
 
-		// PostgreSQL's variant of a BLOB datatype is Bytea, which is a
-		// PITA to work with, so we use base64-encoded data in a TEXT
-		// field instead.
 		if (is_bool($result))
 		{
 			$result = '';
@@ -243,7 +240,7 @@ public function write($sessionID, $sessionData): bool
 				'id'         => $sessionID,
 				'ip_address' => $this->ipAddress,
 				'timestamp'  => time(),
-				'data'       => $this->platform === 'postgre' ? base64_encode($sessionData) : $sessionData,
+				'data'       => $this->platform === 'postgre' ? '\x' . bin2hex($sessionData) : $sessionData,
 			];
 
 			if (! $this->db->table($this->table)->insert($insertData))
@@ -270,7 +267,7 @@ public function write($sessionID, $sessionData): bool
 
 		if ($this->fingerprint !== md5($sessionData))
 		{
-			$updateData['data'] = ($this->platform === 'postgre') ? base64_encode($sessionData) : $sessionData;
+			$updateData['data'] = ($this->platform === 'postgre') ? '\x' . bin2hex($sessionData) : $sessionData;
 		}
 
 		if (! $builder->update($updateData))

user_guide_src/source/libraries/sessions.rst

@@ -596,7 +596,7 @@ For PostgreSQL::
 		"id" varchar(128) NOT NULL,
 		"ip_address" varchar(45) NOT NULL,
 		"timestamp" bigint DEFAULT 0 NOT NULL,
-		"data" text DEFAULT '' NOT NULL
+		"data" bytea DEFAULT '' NOT NULL
 	);
 
 	CREATE INDEX "ci_sessions_timestamp" ON "ci_sessions" ("timestamp");