Hi ,
I have a view which is a union of select of certain feilds from
indentical tables. The problem is when we query a column on
which index exists exists foreach of the tables does not use the
indexes.
But when we query individual tables it uses indexes.
Regds
Mallah.
tradein_clients=# create view sent_enquiry_eyp_iid_ip_cat1 as
select rfi_id,sender_uid,receiver_uid,subject,generated from eyp_rfi UNION
select rfi_id,sender_uid,receiver_uid,subject,generated from iid_rfi UNION
select rfi_id,sender_uid,receiver_uid,subject,generated from ip_rfi UNION
select rfi_id,sender_uid,receiver_uid,subject,generated from catalog_rfi ;
CREATE VIEW
tradein_clients=#
tradein_clients=# explain analyze select rfi_id from
sent_enquiry_eyp_iid_ip_cat1 where sender_uid = 34866;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------
Subquery Scan sent_enquiry_eyp_iid_ip_cat1 (cost=173347.05..182139.66
rows=58617 width=55) (actual time=57514.58..62462.15 rows=73 loops=1)
Filter: (sender_uid = 34866)
-> Unique (cost=173347.05..182139.66 rows=58617 width=55) (actual
time=57514.54..61598.82 rows=586230 loops=1)
-> Sort (cost=173347.05..174812.49 rows=586174 width=55) (actual
time=57514.54..58472.01 rows=586231 loops=1)
Sort Key: rfi_id, sender_uid, receiver_uid, subject, generated
-> Append (cost=0.00..90563.74 rows=586174 width=55) (actual
time=13.17..50500.95 rows=586231 loops=1)
-> Subquery Scan "*SELECT* 1" (cost=0.00..57800.63
rows=369463 width=42) (actual time=13.17..30405.33 rows=369536 loops=1)
-> Seq Scan on eyp_rfi (cost=0.00..57800.63
rows=369463 width=42) (actual time=13.14..28230.00 rows=369536 loops=1)
-> Subquery Scan "*SELECT* 2" (cost=0.00..7317.11
rows=45811 width=47) (actual time=0.04..534.89 rows=45811 loops=1)
-> Seq Scan on iid_rfi (cost=0.00..7317.11
rows=45811 width=47) (actual time=0.03..359.88 rows=45811 loops=1)
-> Subquery Scan "*SELECT* 3" (cost=0.00..22335.44
rows=145244 width=42) (actual time=0.08..17815.66 rows=145251 loops=1)
-> Seq Scan on ip_rfi (cost=0.00..22335.44
rows=145244 width=42) (actual time=0.05..16949.03 rows=145251 loops=1)
-> Subquery Scan "*SELECT* 4" (cost=0.00..3110.56
rows=25656 width=55) (actual time=0.07..469.60 rows=25633 loops=1)
-> Seq Scan on catalog_rfi (cost=0.00..3110.56
rows=25656 width=55) (actual time=0.06..380.64 rows=25633 loops=1)
Total runtime: 62504.24 msec
(15 rows)
tradein_clients=# explain analyze select rfi_id from eyp_rfi where
sender_uid = 34866;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------
Index Scan using eyp_sender_uid_idx on eyp_rfi (cost=0.00..376.11 rows=117
width=4) (actual time=9.88..69.10 rows=12 loops=1)
Index Cond: (sender_uid = 34866)
Total runtime: 69.17 msec
(3 rows)
tradein_clients=#
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