Unindo 2 grandes tabelas postgres usando int8range não dimensionando bem

SELECT *  -- only select columns you need to make it faster
FROM   routing_details r
     , LATERAL (
   SELECT *
   FROM   netblock_details n
   WHERE  n.ip_min <= r.ip_min
   AND    n.ip_max >= r.ip_max
   ORDER  BY n.ip_max - n.ip_min
   LIMIT  1
   ) n;

CREATE INDEX netblock_details_ip_min_max_idx ON netblock_details 
(ip_min, ip_max DESC NULLS LAST);

592,496 * 8,221,675 = 4,871,309,550,800

• 
  juntar duas mesas (sem encontrar a melhor combinação ainda). Na pior das hipóteses, é um produto cartesiano, na melhor das hipóteses, abrange todas as faixas de netblock_details para cada intervalo de routing_details . Você disse que existem várias entradas em netblock_details para cada entrada em routing_details , qualquer coisa de 3 a cerca de 10. Portanto, o resultado dessa junção pode ter ~ 6 milhões de linhas (não muito)
  
• 
  ordenar/particionar o resultado da junção pelo routing_details intervalos e para cada intervalo encontre o melhor (menor) intervalo de cobertura de netblock_details .
  

CREATE TABLE routing_details (
ID        int
,ip_min   int8
,ip_max   int8
,asn      text
,netblock text
);

CREATE TABLE netblock_details (
ID        int
,ip_min   int8
,ip_max   int8
,name     text
,country  text
,source   text
);

SELECT
    netblock_details.ID AS n_ID
    ,netblock_details.ip_max - netblock_details.ip_min AS n_length
    ,r.ID AS r_ID
FROM
    netblock_details
    INNER JOIN LATERAL
    (
        SELECT routing_details.ID
        FROM routing_details
        WHERE
            routing_details.ip_min >= netblock_details.ip_min
            AND routing_details.ip_min <= netblock_details.ip_max
            -- note how routing_details.ip_min is limited from both sides
            -- this would make it possible to scan only (hopefully) small
            -- portion of the table instead of full or half table
            AND routing_details.ip_max <= netblock_details.ip_max
            -- this clause ensures that the whole routing range
            -- is inside the netblock range
    ) AS r ON true

SELECT
    routing_details.*
    ,t.n_ID
    ,netblock_details.*
FROM
    routing_details
    INNER JOIN LATERAL
    (
        SELECT temp.n_ID
        FROM temp
        WHERE temp.r_ID = routing_details.ID
        ORDER BY temp.n_length
        LIMIT 1
    ) AS t ON true
    INNER JOIN netblock_details ON netblock_details.ID = t.n_ID

   |---|
   n1

     |------------------|
     n2

                           |---------------|
                           n3

                                          |-----|
                                          n4

                  |------------------|
                  n5

                     |--------------------------------------|
                     n6

        |---------------------------|
        n7

                      |-----|
                      n8

                      |------------|
                      r
                     start       end

n.start <= r.start AND n.end >= r.end
order by n.length
limit 1 

n.start <= r.start AND n.end >= r.end
order by n.start desc
limit 1 

n.start <= r.start AND n.end >= r.end
order by n.end
limit 1