slow query - only uses indices

Hey Folks,

This query is running really slowly. Sometimes much slower then others. I
have a feeling that there may be contention on one of the indices it is
using. In the explain plan, it looks like it estimates 2 rows but actually
finds 228 rows? Is that really bad?

Query and explain plan are below. Seems like it spend the most time doing
Index Scan using i_tablea_atextfield on tablea ru
(cost=0.00..2265.28rows=2 width=12) (actual time=
0.624..881.313 rows=228 loops=1)

Any suggestions?

SELECT z.atextfield,
z.btextfield,
z.abigintfield,
p.achar255field, p.ptextfield,
z.achar1field, u.aboolfield,
z.textfield1,
z.achar8field,
z.achar16field
FROM tablea ru
INNER JOIN tableb u ON ( u.atextfield = ru.anothertextfield )
INNER JOIN tablec z ON u.atextfield = z.atextfield
INNER JOIN tabled p ON p.id = z.pid
LEFT JOIN tablee m ON u.atextfield = m.atextfield AND m.boolcol5
WHERE ru.atextfield = 'thelookupval'
AND u.boolcol1 IS TRUE
AND u.boolcol2 IS FALSE
AND ru.achar1field <> 'N'
AND ru.boolcol3 IS FALSE
AND NOT EXISTS ( SELECT 'x' FROM tablea fru WHERE fru.atextfield =
ru.anothertextfield AND fru.boolcol3 IS TRUE )
AND EXISTS ( SELECT 'x' FROM tablef s WHERE s.atextfield = ru.atextfieldAND
s.boolcol4 IS TRUE )
ORDER by ru.anothertextfield asc

Sort (cost=2341.96..2341.97 rows=2 width=146) (actual time=
1118.810..1119.098 rows=228 loops=1)
Sort Key: ru.anothertextfield
-> Nested Loop Left Join (cost=0.00..2341.95 rows=2 width=146) (actual
time= 0.930..1117.258 rows=228 loops=1)
-> Nested Loop (cost=0.00..2313.36 rows=2 width=131) (actual time=
0.842..914.554 rows=228 loops=1)
-> Nested Loop (cost=0.00..2296.65 rows=2 width=93) (actual
time= 0.765..901.916 rows=228 loops=1)
-> Nested Loop (cost=0.00..2281.98 rows=2 width=72)
(actual time=0.690..893.648 rows=228 loops=1)
-> Index Scan using i_tablea_atextfield on tablea
ru (cost= 0.00..2265.28 rows=2 width=12) (actual
time=0.624..881.313rows=228 loops=1)
Index Cond: (atextfield =
'thelookupval'::text)
Filter: ((achar1field <> 'N'::bpchar) AND
(boolcol3 IS FALSE) AND (NOT (subplan)) AND (subplan))
SubPlan
-> Index Scan using tablef_pkey on tablef
s (cost=0.00..8.34 rows=1 width=0) (actual time=0.016..0.016 rows=1
loops=228)
Index Cond: (atextfield = $1)
Filter: (boolcol4 IS TRUE)
-> Bitmap Heap Scan on tablea fru (cost=
4.61..90.41 rows=1 width=0) (actual time=3.590..3.590 rows=0 loops=243)
Recheck Cond: (atextfield = $0)
Filter: (boolcol3 IS TRUE)
-> Bitmap Index Scan on
i_tablea_atextfield (cost= 0.00..4.61 rows=22 width=0) (actual time=
0.044..0.044 rows=17 loops=243)
Index Cond: (atextfield = $0)
-> Index Scan using tablec_pkey on tablec z
(cost= 0.00..8.34 rows=1 width=60) (actual time=0.047..0.049 rows=1
loops=228)
Index Cond: (z.atextfield =
ru.anothertextfield)
-> Index Scan using tabled_pkey on tabled p (cost=
0.00..7.32 rows=1 width=29) (actual time=0.030..0.031 rows=1 loops=228)
Index Cond: (p.id = z.pid)
-> Index Scan using tableb_pkey on tableb u (cost=
0.00..8.34 rows=1 width=38) (actual time=0.049..0.051 rows=1 loops=228)
Index Cond: (u.atextfield = ru.anothertextfield)
Filter: ((boolcol1 IS TRUE) AND (boolcol2" IS FALSE))"
-> Index Scan using tablee_atextfield_idx on tablee m (cost=
0.00..14.28 rows=1 width=39) (actual time=0.883..0.883 rows=0 loops=228)
Index Cond: (u.atextfield = m.atextfield)