<span style=3D"font-family:Verdana; color:#000000; font-size:10=
pt;">We are having performance related problems on one of our big data=
Partition tables. The table is partitioned by date and the partitions are =
organized from Jan 2003 thru Dec 2013. We have 268 child partitions ass=
ociated with the Parent table, and we have constraint_exclusion=3Dpartition=
set. =0A =0AThe execution of the SQL query:&nbs=
p; select count(*) from dna_strands; =0Ayields: =
; &n=
bsp; =
; &n=
bsp; =
; QUERY PLAN_____________________________=
________________________________________________________________ =
; =0AAggregate (cost=3D2246778.49..2246778.50 rows=3D1 width=3D0=
) -> Append (0.00..2159647.04 rows=3D34852580 width=3D0)&n=
bsp; -> Seq Scan on dna_strands (cost=3D0.00..0.00 row=
s=3D1 width) Filt=
er: (cid =3D 1) -> Index Scan using dna_stra=
nds_y2003m01_cid on dna_strands_y2003m01 dna_strands (cost=3D0.00..677652 r=
ows=3D1 width=3D0) =
; Index Cond: (cid =3D 1) -> Index Sca=
n using dna_strands_y2003m02_cid on dna_strands_y2003m02 dna_strands (cost=
=3D0.00..974423 rows=3D1 width=3D0) =
Index Cond: (cid =3D 1) =
; -> Index Scan using dna_strands_y2003m03_cid on dna_strands_y2003m03 d=
na_strands (cost=3D0.00..992301 rows=3D1 width=3D0) &n=
bsp; Index Cond: (cid =3D 1) &=
nbsp; ... ...=0A &n=
bsp; ...=0A =0A &nb=
sp; -> Index Scan using dna_strands_y2013m12_cid on dna_strands_y2013m12=
dna_strands (cost=3D0.00..8.27 rows=3D1 width=3D0) &n=
bsp; Index Cond: (cid =3D 1)=0A<d=
iv>Question: Is there any way to modify the Planner to do the inverse of th=
e Index Scan's. In other words, to start the index scans in reverse o=
rder from the most recent date to the oldest date, i.e. "dna_strands_y2=
013m12" backwards. Our application users query much more heavily at the mos=
t recent data that has been ingested into the PostgreSQL database. =
; Would this capability speed up query performance?=0AThanks</di=
v>=0A
