corresponding primary key for max(column)?

is there a better way?

for reasons not defined by me, i cannot constrain the data in the
locations table with unique(ref,ts)

that said Microsoft mappoint craps out if there are duplicate values in
the ref column.

so i need to create a view which returns locations.* for the row which
contains the max(ts) group by ref.

-jason pyeron

assetdb=# \d locations
Table "locations"
Column | Type | Modifiers
--------+--------------------------+------------------------------------------------------
id | integer | not null default nextval('"locations_id_seq"'::text)
ref | integer | not null
ts | timestamp with time zone |
lat | numeric(12,10) | not null
lon | numeric(13,10) | not null
disp | character varying(63) |
Primary key: locations_pkey

assetdb=# select * from locations ;
id | ref | ts | lat | lon | disp
----+-----+-------------------------------+---------------+----------------+--------------------------------------
1 | 1 | 2002-12-22 05:47:26.863774-05 | 39.3373066667 | -76.6245916667 | 0.00MPH 038.6 degrees
2 | 1 | 2002-12-22 05:52:57.211416-05 | 39.3373066667 | -76.6245916667 | 0.00MPH 038.6 degrees
3 | 1 | 2002-12-22 05:54:18.125055-05 | 39.3373066667 | -76.6245916667 | 0.00MPH 038.6 degrees
4 | 2 | 2002-12-22 06:04:48.348906-05 | 40.3373066667 | -76.2459166670 | 0.00MPH 038.6 degrees
5 | 2 | 2002-12-22 06:04:48.348906-05 | 99.9999999999 | -99.9999999999 | Foo Data Point 0.00MPH 038.6 degrees
6 | 1 | 2001-01-01 00:00:00-05 | 38.0000000000 | -76.9000000000 | dfdsfsd
(6 rows)

assetdb=# SELECT
assetdb-# l0.id, l0.ref, l0.ts, l0.lat, l0.lon, l0.disp
assetdb-#
assetdb-# FROM
assetdb-# locations l0
assetdb-#
assetdb-# WHERE
assetdb-# l0.id =
assetdb-# ANY (
assetdb(# SELECT
assetdb(# min(l1.id) AS max
assetdb(#
assetdb(# FROM
assetdb(# (
assetdb(# SELECT
assetdb(# l2.id, l2.ref, l2.ts, l2.lat, l2.lon, l2.disp
assetdb(#
assetdb(# FROM
assetdb(# locations l2
assetdb(#
assetdb(# WHERE
assetdb(# l2.ts =
assetdb(# (
assetdb(# SELECT
assetdb(# max(l3.ts) AS max
assetdb(# FROM
assetdb(# locations l3
assetdb(# WHERE
assetdb(# l3.ref = l2.ref
assetdb(# )
assetdb(# ) as l1
assetdb(#
assetdb(# GROUP BY
assetdb(# l1.ref
assetdb(# )
assetdb-# ;
id | ref | ts | lat | lon | disp
----+-----+-------------------------------+---------------+----------------+-----------------------
3 | 1 | 2002-12-22 05:54:18.125055-05 | 39.3373066667 | -76.6245916667 | 0.00MPH 038.6 degrees
4 | 2 | 2002-12-22 06:04:48.348906-05 | 40.3373066667 | -76.2459166670 | 0.00MPH 038.6 degrees
(2 rows)

Seq Scan on locations l0 (cost=0.00..22535105.55 rows=500 width=98)
SubPlan
-> Materialize (cost=22535.08..22535.08 rows=1 width=8)
-> Aggregate (cost=22535.06..22535.08 rows=1 width=8)
-> Group (cost=22535.06..22535.07 rows=5 width=8)
-> Sort (cost=22535.06..22535.06 rows=5 width=8)
-> Seq Scan on locations l2 (cost=0.00..22535.00 rows=5 width=8)
SubPlan
-> Aggregate (cost=22.51..22.51 rows=1 width=8)
-> Seq Scan on locations l3 (cost=0.00..22.50 rows=5 width=8)

--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
- -
- Jason Pyeron http://www.pyerotechnics.com -
- Owner & Lead Pyerotechnics Development, Inc. -
- +1 410 808 6646 (c) 500 West University Parkway #1S -
- +1 410 467 2266 (f) Baltimore, Maryland 21210-3253 -
- -
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