Test a Partial Data Load

1. Load Dimension Tables

   Load the dimension table data files using the SQL load scripts and actual data files you prepared earlier.

2. Partially Load the Fact Table

   Load 10GB to 50GB of fact table data using the SQL load scripts and actual data files that you prepared earlier. You will complete the fact table bulk load in the next section.

3. Monitor System Resource Usage

   In separate Linux shells, run the top and iostat utilities as described in Monitoring System Resource Usage and watch them while your queries are running.

4. Check Query Execution Times
   1. Use the vsql \timing meta-command to enable the display of query execution time in milliseconds.

      Toggles a display of how long each SQL statement takes, in milliseconds.

   2. Execute the SQL sample query script that you prepared earlier.
   3. Execute several ad-hoc queries.

   If you discover that any of the ad-hoc queries are unacceptably slow, you can drop all tables, append the queries to the sample query script, and start over. The Database Designer may create additional projections based on those queries in order to improve performance.

   At this point Vertica may return errors indicating a primary key or foreign key constraint violation. If that happens, drop all tables, correct the error, and start over. Vertica generally does not actively enforce constraints for performance reasons but detects some constraint violations while performing a join.

5. Check Projection Usage

   In addition to checking query execution times, you can use the EXPLAIN command on certain queries to determine whether or not they are using the expected projections. See the SQL Reference Manual for details.