Different Query plans filtering between dates

Hi all!

I'm trying to find out a solution for this.
I paste you two queries and their query plans:

SELECT se.enduser_id   , se.enduser_number   , se.points   , se.total_messages   , sm.message_order   , to_char(
se.creation_time,'DD/MM/YYYY HH24:MI:SS' ) as first   , MAX( to_char( s.timestamp_in, 'DD/MM/YYYY HH24:MI:SS' ) ) as
last  , s.telecom_operator_id
 
FROM sequence_enduser se , sequence_messages sm , statistics s , statistics_sequence ss
WHERE se.customer_app_config_id = 36052AND se.current_message_id = sm.sequence_message_idAND se.enduser_id =
ss.enduser_idANDss.statistic_id = s.statistic_idAND s.telecom_operator_id <> 0AND s.timestamp_in BETWEEN TO_TIMESTAMP(
'2007121700', 'YYYYMMDD HH24' 
 
) AND TO_TIMESTAMP( '20071224 13', 'YYYYMMDD HH24' )
GROUP BY se.enduser_id, se.enduser_number, se.points, se.total_messages, 
sm.message_order, se.creation_time, s.telecom_operator_id
ORDER BY enduser_number ASC
                                                                                                               
QUERY PLAN                                 

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


Sort  (cost=31324.84..31513.34 rows=75402 width=56) (actual 
time=3274.487..3282.754 rows=20275 loops=1) Sort Key: se.enduser_number ->  GroupAggregate  (cost=22200.32..25216.40
rows=75402width=56) 
 
(actual time=2487.328..3028.551 rows=20275 loops=1)       ->  Sort  (cost=22200.32..22388.83 rows=75402 width=56)
(actual
 
time=2487.218..2519.218 rows=75367 loops=1)             Sort Key: se.enduser_id, se.enduser_number, se.points, 
se.total_messages, sm.message_order, se.creation_time, 
s.telecom_operator_id             ->  Hash Join  (cost=8697.77..16091.89 rows=75402 
width=56) (actual time=538.019..1812.511 rows=75367 loops=1)                   Hash Cond: ("outer".enduser_id =
"inner".enduser_id)                  ->  Merge Join  (cost=7557.54..13066.61 rows=75402 
 
width=25) (actual time=461.141..1599.325 rows=75367 loops=1)                         Merge Cond: ("outer".statistic_id
=
 
"inner"."?column3?")                         ->  Index Scan using pk_st_statistic_id on 
"statistics" s  (cost=0.00..3800.23 rows=75373 width=28) (actual 
time=0.133..836.972 rows=75367 loops=1)                               Filter: ((telecom_operator_id <> 
0::numeric) AND (timestamp_in >= to_timestamp('20071217 00'::text, 
'YYYYMMDD HH24'::text)) AND (timestamp_in <= to_timestamp('20071224 
13'::text, 'YYYYMMDD HH24'::text)))                         ->  Sort  (cost=7557.54..7750.19 rows=77061 
width=16) (actual time=460.925..495.810 rows=76940 loops=1)                               Sort Key:
(ss.statistic_id)::numeric                              ->  Seq Scan on statistics_sequence ss  
 
(cost=0.00..1302.61 rows=77061 width=16) (actual time=0.014..106.970 
rows=77046 loops=1)                   ->  Hash  (cost=1088.38..1088.38 rows=20740 
width=39) (actual time=76.854..76.854 rows=20285 loops=1)                         ->  Hash Join  (cost=20.02..1088.38
rows=20740
 
width=39) (actual time=0.321..55.377 rows=20285 loops=1)                               Hash Cond:
("outer".current_message_id= 
 
"inner".sequence_message_id)                               ->  Seq Scan on sequence_enduser se  
(cost=0.00..757.25 rows=20740 width=41) (actual time=0.010..27.174 
rows=20285 loops=1)                                     Filter: (customer_app_config_id = 
36052)                               ->  Hash  (cost=19.82..19.82 rows=82 
width=6) (actual time=0.303..0.303 rows=101 loops=1)                                     ->  Seq Scan on
sequence_messages
 
sm  (cost=0.00..19.82 rows=82 width=6) (actual time=0.102..0.215 
rows=101 loops=1)
Total runtime: 3321.379 ms



SELECT se.enduser_id   , se.enduser_number   , se.points   , se.total_messages   , sm.message_order   , to_char(
se.creation_time,'DD/MM/YYYY HH24:MI:SS' ) as first   , MAX( to_char( s.timestamp_in, 'DD/MM/YYYY HH24:MI:SS' ) ) as
last  , s.telecom_operator_id
 
FROM sequence_enduser se , sequence_messages sm , statistics s , statistics_sequence ss
WHERE se.customer_app_config_id = 36052AND se.current_message_id = sm.sequence_message_idAND se.enduser_id =
ss.enduser_idANDss.statistic_id = s.statistic_idAND s.telecom_operator_id <> 0AND s.timestamp_in BETWEEN TO_TIMESTAMP(
'2007122400', 'YYYYMMDD HH24' 
 
) AND TO_TIMESTAMP( '20071224 12', 'YYYYMMDD HH24' )
GROUP BY se.enduser_id, se.enduser_number, se.points, se.total_messages, 
sm.message_order, se.creation_time, s.telecom_operator_id
ORDER BY enduser_number ASC



---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


Sort  (cost=5832.01..5832.01 rows=1 width=56) (actual 
time=205888.361..205888.546 rows=452 loops=1) Sort Key: se.enduser_number ->  GroupAggregate  (cost=5831.96..5832.00
rows=1width=56) (actual 
 
time=205874.680..205885.162 rows=452 loops=1)       ->  Sort  (cost=5831.96..5831.96 rows=1 width=56) (actual 
time=205874.620..205875.244 rows=1436 loops=1)             Sort Key: se.enduser_id, se.enduser_number, se.points, 
se.total_messages, sm.message_order, se.creation_time, 
s.telecom_operator_id             ->  Nested Loop  (cost=0.00..5831.95 rows=1 width=56) 
(actual time=529.626..205861.898 rows=1436 loops=1)                   ->  Nested Loop  (cost=0.00..5828.92 rows=1 
width=58) (actual time=529.608..205843.305 rows=1436 loops=1)                         ->  Nested Loop
(cost=0.00..5825.72rows=1 
 
width=25) (actual time=529.571..205816.745 rows=1436 loops=1)                               Join Filter: 
(("inner".statistic_id)::numeric = "outer".statistic_id)                               ->  Seq Scan on "statistics" s

(cost=0.00..3367.20 rows=1 width=28) (actual time=389.645..422.342 
rows=1436 loops=1)                                     Filter: ((telecom_operator_id <> 
0::numeric) AND (timestamp_in >= to_timestamp('20071224 00'::text, 
'YYYYMMDD HH24'::text)) AND (timestamp_in <= to_timestamp('20071224 
14'::text, 'YYYYMMDD HH24'::text)))                               ->  Seq Scan on statistics_sequence ss  
(cost=0.00..1302.61 rows=77061 width=16) (actual time=0.003..54.903 
rows=77049 loops=1436)                         ->  Index Scan using pk_seqenduser_enduserid 
on sequence_enduser se  (cost=0.00..3.18 rows=1 width=41) (actual 
time=0.014..0.015 rows=1 loops=1436)                               Index Cond: (se.enduser_id = 
"outer".enduser_id)                               Filter: (customer_app_config_id = 36052)                   ->  Index
Scanusing pk_seqmsms_seqmsgid on 
 
sequence_messages sm  (cost=0.00..3.01 rows=1 width=6) (actual 
time=0.008..0.009 rows=1 loops=1436)                         Index Cond: ("outer".current_message_id = 
sm.sequence_message_id)
Total runtime: 205889.055 ms



As you can see, the only difference between the two queries, is the date 
between i filter. Only when I filter between today, the total runtime 
grows up till heaven. I don't know what is happening here... The query 
plan changes with that damn Nested Loop on third steps...

Note: IF the query is ...  AND s.timestamp_in BETWEEN TO_TIMESTAMP( 
'20071223 00', 'YYYYMMDD HH24' ) AND TO_TIMESTAMP( '20071223 12', 
'YYYYMMDD HH24' )... (Yesterday) The query plan is like the first one... 
The Faster.

Please... I need help!