SELECT
  regexp_extract('https://docs.fluentd.org/v0.12/articles/out_file'   ,'(docs.fluentd.org).*(out_file)',1) AS pat1,
  regexp_extract('https://docs.fluentd.org/v0.12/articles/out_forward','(docs.fluentd.org).*(out_file)',1) AS pat2,
  regexp_extract('https://www.fluentd.org/v0.12/articles/out_file'    ,'(docs.fluentd.org).*(out_file)',1) AS pat3,
  regexp_extract('out_file/article/docs.fluentd.org/'                 ,'(docs.fluentd.org).*(out_file)',1) AS pat4,

  regexp_extract('https://docs.fluentd.org/v0.12/articles/out_file'   ,'(docs.fluentd.org).*(out_file)',2) AS pat5,
  regexp_extract('https://docs.fluentd.org/v0.12/articles/out_forward','(docs.fluentd.org).*(out_file)',2) AS pat6,
  regexp_extract('https://www.fluentd.org/v0.12/articles/out_file'    ,'(docs.fluentd.org).*(out_file)',2) AS pat7,
  regexp_extract('out_file/article/docs.fluentd.org/'                 ,'(docs.fluentd.org).*(out_file)',2) AS pat8
FROM access_log
LIMIT 1