[ https://issues.apache.org/jira/browse/HIVE-165?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Adam Kramer updated HIVE-165: ----------------------------- Description: The last step in the unholy triumvirate of statistical built-ins is the variance. We already have the n (count) and the mean (avg). I currently have a job or two that filters all of the data into a single reducer which just computes mean/n/variance and writes it to a table...so my guess is that this would be a pretty big speed increase. Not a huge deal though, as computing the variance myself is trivial. (Average, variance, and n can be co-computed in one pass, so if you're doing var() you can basically have avg() and count() for free.) was:The last step in the unholy triumvirate of statistical built-ins is the variance...we already have the n (count) and the mean (avg). I currently have one reduce step that just computes mean/n/variance and writes it to a table, so my guess is that this would be a pretty big speed increase. Not a huge deal though, as computing the variance myself is trivial. (Average, variance, and n can be co-computed in one pass) > var(col) built-in to go with avg(col) and count(col) > ---------------------------------------------------- > > Key: HIVE-165 > URL: https://issues.apache.org/jira/browse/HIVE-165 > Project: Hadoop Hive > Issue Type: Wish > Reporter: Adam Kramer > Priority: Minor > > The last step in the unholy triumvirate of statistical built-ins is the > variance. We already have the n (count) and the mean (avg). I currently have > a job or two that filters all of the data into a single reducer which just > computes mean/n/variance and writes it to a table...so my guess is that this > would be a pretty big speed increase. Not a huge deal though, as computing > the variance myself is trivial. > (Average, variance, and n can be co-computed in one pass, so if you're doing > var() you can basically have avg() and count() for free.) -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.