[ADMIN] Too slow

[Sabio - PSQL]

How can I improve speed on my queries. For example this query takes one 
day executing itself and it has not finalized !!!
"create table tmp_partes as select * from partes where identificacion 
not in (select cedula from sujetos)"

partes have 1888000 rows, an index on identificacion
sujetos have 5500000 rows, an index on cedula


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