OK, the sample query is attached (hopefully attachments are allowed) as "query.sql". The "master table" definition is attached as "table1.sql". The "detail table" definition is attached as "table2.sql". The EXPLAIN (ANALYZE, BUFFERS) output is here: http://explain.depesz.com/s/vd5
Could you try chaning your query and sending the EXPLAIN of the following?
Instead of `node_id in ('175769', '175771', ...)` try `node_in IN (VALUES('175769'), ('175771'), ... )`.
-- Matheus de Oliveira Analista de Banco de Dados Dextra Sistemas - MPS.Br nível F! www.dextra.com.br/postgres