Sorting performance vs. MySQL

I have the exact same table of data in both MySQL and Postgresql. In Postgresql:

tpcc=# \d metarelcloud_transactionlog
Table
"public.metarelcloud_transactionlog"
Column | Type |
Modifiers
---------------------+-----------------------+--------------------------------------------------------------------------
id | integer | not null default
nextval('metarelcloud_transactionlog_id_seq'::regclass)
transactionid | integer | not null
queryid | smallint | not null
tableid | character varying(30) | not null
tupleid | integer | not null
querytype | character varying | not null
graphpartition | smallint |
replicatedpartition | smallint |
justifiedpartition | smallint |
hashpartition | smallint |
nodeid | integer |
manualpartition | smallint |
Indexes:
"metarelcloud_transactionlog_pkey" PRIMARY KEY, btree (id)
Check constraints:
"metarelcloud_transactionlog_graphpartition_check" CHECK
(graphpartition >= 0)
"metarelcloud_transactionlog_hashpartition_check" CHECK (hashpartition >= 0)
"metarelcloud_transactionlog_justifiedpartition_check" CHECK
(justifiedpartition >= 0)
"metarelcloud_transactionlog_manualpartition_check" CHECK
(manualpartition >= 0)
"metarelcloud_transactionlog_querytype_check" CHECK
(querytype::text = ANY (ARRAY['select'::character varying,
'insert'::character varying, 'delete'::character varying,
'update'::character varying]::text[]))
"metarelcloud_transactionlog_replicatedpartition_check" CHECK
(replicatedpartition >= 0)

In MySQL:

CREATE TABLE `metarelcloud_transactionlog` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`transactionid` int(11) NOT NULL,
`queryid` tinyint(4) NOT NULL,
`tableid` varchar(30) NOT NULL,
`tupleid` int(11) NOT NULL,
`querytype` enum('select','insert','delete','update') NOT NULL,
`graphpartition` tinyint(3) unsigned DEFAULT NULL,
`replicatedpartition` tinyint(3) unsigned DEFAULT NULL,
`justifiedpartition` tinyint(3) unsigned DEFAULT NULL,
`hashpartition` tinyint(3) unsigned DEFAULT NULL,
`nodeid` int(11) DEFAULT NULL,
`manualpartition` tinyint(3) unsigned DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `transactionid` (`transactionid`),
KEY `tableid` (`tableid`,`tupleid`),
KEY `nodeid` (`nodeid`)
) ENGINE=MyISAM AUTO_INCREMENT=50410166 DEFAULT CHARSET=latin1

I'm running:

select * from metarelcloud_transactionlog order by transactionid;

It takes MySQL 6 minutes, but Postgresql is still running after 70
minutes. Is there something like a glaring misconfiguration that I'm
overlooking? Thanks in advance.
--
Yang Zhang
http://www.mit.edu/~y_z/