Performance of UNION in RedShift

Has anyone used UNION successfully with RedShift in DOMO?  I have a DF that seems to stall on the query using the UNION.  I don't know if it would error out b/c I'm too impatient (after waiting 30 m), but I ended up revising how I wrote the script to not need the UNION...but was curious why it would have been delayed SOOOO long...300k rows unioning on 300 rows....

 

Thanks and have a great day.

Best Answer

  • gwsv-it
    Accepted Answer

    If you're not worried about removing duplicates, then UNION ALLshould skip the DISTINCT step of the UNION operation and improve your performance a bit.

Answers

  • I just introduced my palm to my head after I read that.  I did leave off ALL.  Crap.  Thanks for chiming in and helping me out.  Good catch!  I should have used UNION ALL but left it out.