Re: How to query and index for customer with lastname and city

On 3/4/06, Joost Kraaijeveld <J(dot)Kraaijeveld(at)askesis(dot)nl> wrote:
> Below is what I actually have. Given the fact that it takes forever to get
> a result (> 6 seconds) , there must be something wrong with my solution or
> my expectation. Can anyone tell what I should do to make this query go
> faster ( or convince me to wait for the result ;-()?
> Explain analyze after a full alayse vacuum:
> Sort (cost=54710.68..54954.39 rows=97484 width=111) (actual
> time=7398.971..7680.405 rows=96041 loops=1)
> Sort Key: btrim(upper(customers.lastname)), btrim(upper(addresses.city))
> -> Hash Join (cost=14341.12..46632.73 rows=97484 width=111) (actual
> time=1068.862..5472.788 rows=96041 loops=1)
> Hash Cond: ("outer".contactaddress = "inner".objectid)
> -> Seq Scan on customers (cost=0.00..24094.01 rows=227197
> width=116) (actual time=0.018..1902.646 rows=223990 loops=1)
> Filter: (btrim(upper(lastname)) >= 'JANSEN'::text)
> -> Hash (cost=13944.94..13944.94 rows=158473 width=75) (actual
> time=1068.467..1068.467 rows=158003 loops=1)
> -> Bitmap Heap Scan on addresses (cost=1189.66..13944.94
> rows=158473 width=75) (actual time=71.259..530.986 rows=158003 loops=1)
> Recheck Cond: (btrim(upper(city)) >= 'NIJMEGEN'::text)
> -> Bitmap Index Scan on
> prototype_addresses_trim_upper_city (cost=0.00..1189.66
> rows=158473 width=0) (actual time=68.290..68.290 rows=158003 loops=1)
> Index Cond: (btrim(upper(city)) >=
> 'NIJMEGEN'::text)
> Total runtime: 7941.095 ms

explain clearly shows, that index is used for addresses scan, but it
is not so for users.
explain estimates that 227197 customers match the lastname criteria -
which looks awfuly high.
how many record do you have in the customers table?

i would try to create index test on customers(contactAddress,
trim(uppercase(lastname)));
or with other ordring of fields.

try this - create the index, make analyze of customers table, and
recheck explain.
then try the second index in the same manner.

maybe this could of some help...

depesz