BigQuery | JOIN EACH を複数使うとメチャクチャ重い問題 ref: http://qiita.com/Yinaura/items/13cc2b206921efd7172b

file0.sql

SELECT
  *
FROM
  dataset.table1 AS table1
JOIN
  dataset.table2 AS table2
ON
  table1.id = table2.id
JOIN
  dataset.table3 AS table3
ON
  table2.category = table3.category

file1.sql

SELECT
  *
FROM
  dataset.table1 AS table1
JOIN EACH
  dataset.table2 AS table2
ON
  table1.id = table2.id
JOIN EACH
  dataset.table3 AS table3
ON
  table2.category = table3.category

file2.sql

SELECT
  *
FROM
  dataset.table1 AS table1
JOIN EACH
  dataset.table2 AS table2
ON
  table1.id = table2.id
JOIN EACH
  dataset.table3 AS table3
ON
  table2.category = table3.category