Oracle und seine Statistiken

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Zum Aktualisieren von Tabellenstatistiken:

begin
    SYS.dbms_stats.delete_table_stats(user, myTbl );

    SYS.DBMS_STATS.gather_table_stats (
      ownname        => 'LABP'
     ,tabname        => 'myTbl'
    ,estimate_percent  => 25
    ,block_sample      => TRUE
-- besser weglassen!   ,method_opt        => 'FOR ALL INDEXED COLUMNS SIZE 254 '
    ,degree            => 4
    ,cascade           => TRUE
    ,no_invalidate     => FALSE);
end;
/


Zum Prüfen, welche Ergebnisse ermittelt wurden:

SELECT column_name, num_distinct
     , histogram, num_buckets
     , TO_CHAR (last_analyzed, 'yyyy-dd-mm hh24:mi:ss') last_analyzed
  FROM user_tab_col_statistics
 WHERE table_name = myTbl




Quelle: http://structureddata.org/2008/10/14/dbms_stats-method_opt-and-for-all-indexed-columns/

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