MIYAKAWA Taku created PIG-3215:
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Summary: [piggybank] Add LTSVLoader to load LTSV (Labeled
Tab-separated Values) files
Key: PIG-3215
URL: https://issues.apache.org/jira/browse/PIG-3215
Project: Pig
Issue Type: New Feature
Components: piggybank
Reporter: MIYAKAWA Taku
LTSV, or Labeled Tab-separated Values format is now getting popular in Japan
for log files, especially of web servers. The goal of this jira is to add
LTSVLoader in PiggyBank to load LTSV files.
LTSV is based on TSV thus columns are separated by tab characters. Additionally
each of columns includes a label and a value, separated by ":" character.
Read about LTSV on http://ltsv.org/.
h4. Example LTSV file (access.log)
Columns are separated by tab characters.
{noformat}
host:host1.example.org req:GET /index.html ua:Opera/9.80
host:host1.example.org req:GET /favicon.ico ua:Opera/9.80
host:pc.example.com req:GET /news.html ua:Mozilla/5.0
{noformat}
h4. Usage 1: Extract fields from each line
Users can specify an input schema and get columns as Pig fields.
This example loads the LTSV file shown in the previous section.
{code}
-- Parses the access log and count the number of lines
-- for each pair of the host column and the ua column.
access = LOAD 'access.log' USING
org.apache.pig.piggybank.storage.LTSVLoader('host:chararray, ua:chararray');
grouped_access = GROUP access BY (host, ua);
count_for_host_ua = FOREACH grouped_access GENERATE group.host, group.ua,
COUNT(access);
DUMP count_for_host_ua;
{code}
The below text will be printed out.
{noformat}
(host1.example.org,Opera/9.80,2)
(pc.example.com,Firefox/5.0,1)
{noformat}
h4. Usage 2: Extract a map from each line
Users can get a map for each LTSV line. The key of a map is a label of the LTSV
column. The value of a map comes from characters after ":" in the LTSV column.
{code}
-- Parses the access log and projects the user agent field.
access = LOAD 'access.log' USING org.apache.pig.piggybank.storage.LTSVLoader()
AS (m:map[]);
user_agent = FOREACH access GENERATE m#'ua' AS ua;
DUMP user_agent;
{code}
The below text will be printed out.
{noformat}
(Opera/9.80)
(Opera/9.80)
(Firefox/5.0)
{noformat}
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