Hi, in a web app we have a query that we want to show in limited results at a time, this one executes in 10 seconds if i use limit but executes in 300ms if i remove it. why is that happening? the query is using and index for avoiding the sort so the nestloop should go only for the first 20 records on tgen_persona, no? below some more info postgresql 8.3.7 ram 32GB shared_buffers 8GB work_mem 8MB tgen_persona has 185732 records and tcom_invitacion is a partitioned (by dates: 1 month every partition) table and has more than 29million records in the partitions explain analyze here: http://explain.depesz.com/s/B4 the situation improves if i disable nestloops, explain analyze with nestloop off here: http://explain.depesz.com/s/Jv select Per.razon_social as MAIL,inv.cata_esta_calificacion, inv.observa_calificacion, to_char(inv.fech_crea,'YYYY:MM:DD') as fech_crea, case when (( select cod_estado FROM TPRO_PROVEEDOR WHERE id_proveedor = (select max(a.id_proveedor) from tpro_proveedor a where persona_id = Inv.persona_id ) )='Habilitado') then 'Habilitado' else 'Deshabilitado' end as empresa_id from tgen_persona Per, tcom_invitacion Inv where Per.persona_id = Inv.persona_id and inv.id_soli_compra = '60505' ORDER BY Per.razon_social asc limit 20 offset 0 -- Atentamente, Jaime Casanova Soporte y capacitación de PostgreSQL Asesoría y desarrollo de sistemas Guayaquil - Ecuador Cel. +59387171157 -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
