Answers

• JoeGonzalezVertDBA Vertica Customer ✭

  April 2020

  I think it makes a difference when it comes to recommending a projection that is unsegmented (which is recommended for smaller tables) vs a projection that is segmented. My personal rule of thumb is to default to an unsegmented projection on a table with less than 1 million rows. I am not sure exactly what amount the DBD uses when recommending one vs the other but I do believe itt takes itt into account for this purpose only.

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• Jim_Knicely - Select Field - Administrator

  April 2020 edited April 2020

  Check out:

  dbadmin=> SELECT parameter_name, default_value, description FROM configuration_parameters WHERE parameter_name IN ('DBDRepLargeRowCountPct', 'DBDRepSmallRowCountPct', 'DBDLargestTableRowCountBoundary');
           parameter_name          | default_value |                                                                                                      description                                         
  ---------------------------------+---------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
   DBDRepLargeRowCountPct          | 1.000000      | If the largest fact table has more than <DBDLargestTableRowCountBoundary> rows, then use this percentage off the largest fact table to define the number of rows below which a table should be replicated Default: 1%
   DBDRepSmallRowCountPct          | 10.000000     | If the largest fact table has less than <DBDLargestTableRowCountBoundary> rows, then use this percentage off the largest fact table to define the number of rows below which a table should be replicated Default: 10%
   DBDLargestTableRowCountBoundary | 1000000       | Number of minimum rows expected in Fact Table, default 1M rows
  (3 rows)
  

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