There is real power in combing Vertica functions to accomplish almost any task in SQL.
Example:
I want to extract the last sub-directory from the STORAGE_PATH column in the DISK_STORAGE system table. Below are 2 methods for doing that combining several Vertica built-in functions.
dbadmin=> SELECT node_name,
dbadmin-> storage_path,
dbadmin-> split_part(storage_path, '/', regexp_count(storage_path, '/')+1) last_subdir
dbadmin-> FROM disk_storage;
node_name | storage_path | last_subdir
------------------+------------------------------------------------------+-----------------------
v_vmart_node0001 | /home/dbadmin/vmart/v_vmart_node0001_catalog/Catalog | Catalog
v_vmart_node0001 | /home/dbadmin/vmart/v_vmart_node0001_data | v_vmart_node0001_data
v_vmart_node0001 | /home/dbadmin/usershr | usershr
v_vmart_node0002 | /home/dbadmin/vmart/v_vmart_node0002_catalog/Catalog | Catalog
v_vmart_node0002 | /home/dbadmin/vmart/v_vmart_node0002_data | v_vmart_node0002_data
v_vmart_node0002 | /home/dbadmin/usershr | usershr
v_vmart_node0003 | /home/dbadmin/vmart/v_vmart_node0003_catalog/Catalog | Catalog
v_vmart_node0003 | /home/dbadmin/vmart/v_vmart_node0003_data | v_vmart_node0003_data
v_vmart_node0003 | /home/dbadmin/usershr | usershr
(9 rows)
vmart@sandbox1=> SELECT node_name,
vmart@sandbox1-> storage_path,
vmart@sandbox1-> SUBSTR(storage_path, INSTR(storage_path, '/', -1)+1) last_subdir
vmart@sandbox1-> FROM disk_storage;
node_name | storage_path | last_subdir
-----------------+------------------------------------------------------+-----------------------
v_vmart_node0001 | /home/dbadmin/vmart/v_vmart_node0001_catalog/Catalog | Catalog
v_vmart_node0001 | /home/dbadmin/vmart/v_vmart_node0001_data | v_vmart_node0001_data
v_vmart_node0001 | /home/dbadmin/usershr | usershr
v_vmart_node0002 | /home/dbadmin/vmart/v_vmart_node0002_catalog/Catalog | Catalog
v_vmart_node0002 | /home/dbadmin/vmart/v_vmart_node0002_data | v_vmart_node0002_data
v_vmart_node0002 | /home/dbadmin/usershr | usershr
v_vmart_node0003 | /home/dbadmin/vmart/v_vmart_node0003_catalog/Catalog | Catalog
v_vmart_node0003 | /home/dbadmin/vmart/v_vmart_node0003_data | v_vmart_node0003_data
v_vmart_node0003 | /home/dbadmin/usershr | usershr
(9 rows)
Helpful Links:https://www.vertica.com/docs/latest/HTML/Content/Authoring/SQLReferenceManual/Functions/String/StringFunctions.htm
https://www.vertica.com/docs/latest/HTML/Content/Authoring/SQLReferenceManual/Functions/RegularExpressions/RegularExpressionFunctions.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!
