Example:
dbadmin=> SELECT random() random1, random() random2, random() random3;
random1 | random2 | random3
------------------+-------------------+-------------------
0.206615947652608 | 0.308142327470705 | 0.124399376800284
(1 row)
dbadmin=> SELECT random() random1;
random1
-------------------
0.517856472404674
(1 row)
Notice above that each time I called the RANDOM function I got a new random value. But what if I need to generate a random number and use it in multiple places in my query? For this case, you can use the SEEDED_RANDOM function.
dbadmin=> SELECT seeded_random(1) random1, seeded_random(1) random1,
dbadmin-> seeded_random(2) random2, seeded_random(2) random2;
random1 | random1 | random2 | random2
-------------------+-------------------+------------------+------------------
0.417021998437122 | 0.417021998437122 | 0.43599490262568 | 0.43599490262568
(1 row)
You can even reference the same seeded random number in subsequent SQL statements in the same session! That is, I can get the same random numbers RANDOM1 and RANDOM2 that I generated above in a new query:
dbadmin=> SELECT seeded_random(1) random1, seeded_random(2) random2;
random1 | random2
-------------------+------------------
0.417021998437122 | 0.43599490262568
(1 row)
Helpful Link:https://www.vertica.com/docs/latest/HTML/Content/Authoring/SQLReferenceManual/Functions/Mathematical/RANDOM.htm
Have fun!
About the Author
James Knicely
Vertica Field Chief Technologist
I've had the privilege of working with many database technologies in my career. But after being introduced to Vertica in May of 2011 as a client, I was hooked on the new technology after witnessing a query run in milliseconds that had previously ran for hours on the legacy database we had in place. It was then that I knew I wanted to eventually join the Vertica team, and 4 years later I did! I am currently a Vertica evangelist and am ready to help you get on board! Please feel free to reach out to me with any questions you have about Vertica and make sure to follow my Vertica Quick Tips!
