fluent-plugin-bigquery利用時に、tableを動的に設定する ref: http://qiita.com/twingo-b@github/items/864a3eb22083e7f0f239

file0.txt

<source>
  type tail
  format apache
  time_format %d/%b/%Y:%H:%M:%S %z
  path /var/log/httpd/access_log
  tag td.apache_access_log
  pos_file /var/lib/fluent/td.apache_access_log.pos
</source>

...

<match td.apache_access_log>
  type record_reformer
  enable_ruby true
  tag ${tag}.${time.strftime('%Y%m')}
  <record>
    input_tag    ${tag}
    port         ${port}
    host         ${host}
    user         ${user}
    method       ${method}
    path         ${path}
    http_version ${http_version}
    conde        ${conde}
    size         ${size}
    referer      ${referer}
    agent        ${agent}
  </record>
</match>

<match td.**>
  type forest
  subtype copy
  remove_prefix td
  <template>
    # Amazon S3
    <store>
      type s3
      s3_bucket s3-bucket
      path /
      buffer_path /var/log/td-agent/buffer/s3.${tag}.*.buffer
      time_slice_format ${tag_parts[0]}/%Y/%Y%m%d/${tag}-%Y%m%d-%H
    </store>
  </template>
  # Google BigQuery
  <case apache_access_log.**>
    <store>
      type bigquery
      method insert
      auth_method private_key
      email XXXXXXXXXXXX@developer.gserviceaccount.com
      private_key_path /etc/td-agent/XXXXXXXXXXXX-privatekey.p12
      project your-project-id
      dataset your_dataset
      table apache_access_log_${tag_parts[-1]}
      time_format %s
      time_field time
      schema_path /etc/td-agent/apache_access_log_schema.json
    </store>
  </case>
</match>

file1.txt

but, please note that enabling ruby codes is not encouraged by security reasons and also in terms of the performance.