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Post date: Oct 05, 2012 2:48:24 PM
Viewing Data Distribution in v4.x
To view the data distribution of a table’s rows (the number of rows on each segment), you can run a query such as:
# SELECT gp_segment_id, count(*)
FROM table_name GROUP BY gp_segment_id;
To see the data distribution of a table’s rows on segment servers and the directory location of where the data is located, you can run a query such as:
# SELECT table_name.gp_segment_id,hostname, fselocation as datadir,count(*)
FROM table_name, pg_filespace_entry pgfse,gp_segment_configuration gsc
WHERE gsc.dbid=pgfse.fsedbid and table_name.gp_segment_id= pgfse.fsedbid
GROUP BY table_name.gp_segment_id,hostname,datadir
ORDER BY gp_segment_id;
Notes: Balanced Distribution
A table is considered to have a balanced distribution if all of the segments have roughly the same number of rows.