[GENERAL] Row value expression much faster than equivalent OR clauses

A library my application is using does a "scan a batch at a time" loop over a table of events, keeping track of its last position so it can start the next query in the right place.

SELECT eventIdentifier, aggregateIdentifier, sequenceNumber, timeStamp, payloadType,
    payloadRevision, payload, metaData
FROM DomainEventEntry e
WHERE ((e.timeStamp > '2016-12-19T20:34:22.315Z')
        OR (e.timeStamp = '2016-12-19T20:34:22.315Z'
            AND e.sequenceNumber > 0)
        OR (e.timeStamp = '2016-12-19T20:34:22.315Z'
            AND e.sequenceNumber = 0
            AND e.aggregateIdentifier > 'dev:642e1953-2562-4768-80d9-0c3af9b0ff84'))
AND (type = 'transAggPrototype')
ORDER BY e.timeStamp ASC, e.sequenceNumber ASC, e.aggregateIdentifier ASC
LIMIT 100;

This uses the index on the three columns it's using for ordering of events, but (if I'm reading the explain output correctly) does a full scan of the index.

 Limit  (cost=0.55..1349.44 rows=100 width=576) (actual time=526.814..527.238 rows=100 loops=1)
   ->  Index Scan using domainevententry_ts_seq_agg on domainevententry e  (cost=0.55..92494.44 rows=6857 width=576) (actual time=526.811..527.035 rows=100 loops=1)
         Filter: (((type)::text = 'transAggPrototype'::text) AND ((("timestamp")::text > '2016-12-19T20:34:22.315Z'::text) OR ((("timestamp")::text = '2016-12-19T20:34:22.315Z'::text) AND (sequencenumber > 0)) OR ((("timestamp")::text = '2016-12-19T20:34:22.315Z'::text) AND (sequencenumber = 0) AND ((aggregateidentifier)::text > 'dev:642e1953-2562-4768-80d9-0c3af9b0ff84'::text))))
         Rows Removed by Filter: 332183
 Planning time: 1.893 ms
 Execution time: 527.368 ms


I played around with it a little and one thing I tried was to restructure the WHERE clause using a row value expression that's semantically equivalent to the original.

SELECT eventIdentifier, aggregateIdentifier, sequenceNumber, timeStamp, payloadType,
    payloadRevision, payload, metaData
FROM DomainEventEntry e
WHERE (e.timeStamp, e.sequenceNumber, e.aggregateIdentifier) >
        ('2016-11-19T20:34:22.315Z', 0, 'dev:642e1953-2562-4768-80d9-0c3af9b0ff84')
AND (type = 'transAggPrototype')
ORDER BY e.timeStamp ASC, e.sequenceNumber ASC, e.aggregateIdentifier ASC
LIMIT 100;

This ends up being a LOT faster:

 Limit  (cost=0.55..56.81 rows=100 width=576) (actual time=0.065..0.667 rows=100 loops=1)
   ->  Index Scan using domainevententry_ts_seq_agg on domainevententry e  (cost=0.55..65581.93 rows=116573 width=576) (actual time=0.062..0.437 rows=100 loops=1)
         Index Cond: (ROW(("timestamp")::text, sequencenumber, (aggregateidentifier)::text) > ROW('2016-11-19T20:34:22.315Z'::text, 0, 'dev:642e1953-2562-4768-80d9-0c3af9b0ff84'::text))
         Filter: ((type)::text = 'transAggPrototype'::text)
         Rows Removed by Filter: 235
 Planning time: 1.705 ms
 Execution time: 0.795 ms


I wonder if the query planner could recognize that the two queries are equivalent and choose the second plan for the OR-clause version, or at least use the index more efficiently. This is on PostgreSQL 9.5.2.

-Steve