Re: Correlation in pg_stats

Hello

Do you want to search for tables with many unordered rows?

  SELECT
    schemaname, tablename, correlation
  FROM
    pg_stats
  WHERE
    abs(correlation) < 0.2 and
    schemaname not in ('pg_catalog', 'information_schema')
  ;

Or do you want to put the table in order?

  BEGIN;
  CREATE TABLE tbl_test_new (LIKE tbl_test INCLUDING ALL);
  INSERT INTO tbl_test_new SELECT * FROM tbl_test ORDER BY id;
  DROP TABLE tbl_test;
  TABLE tbl_test_new RENAME TO tbl_test;
  COMMIT;

If you really want to get a correlation of near 0 try

  INSERT INTO tbl_test (name) SELECT random() FROM generate_series(1, 100);

bye,

-christian-

Am Mon, 26 Nov 2012 01:52:21 -0800 (PST)
schrieb classical_89 <luongnx512@gmail.com>:

> Hi,First sorry for my bad English :D.I'm new in PostgreSQL and
> database .Now i'm researching about statistic correlation .I want to
> make a example with the table -assume that I have tbl_test table and
> two column - id & name - and do something to get correlation of a
> column is near 0 (zero).What step can i do  ?
> Thanks for your support :)
>
>
>
> --
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>
>