clintropolis commented on a change in pull request #8894: document SQL compatible null handling mode URL: https://github.com/apache/incubator-druid/pull/8894#discussion_r348299641
########## File path: docs/design/segments.md ########## @@ -143,6 +143,11 @@ the 'column data' is an array of values. Additionally, a row with *n* values in 'column data' will have *n* non-zero valued entries in bitmaps. +## SQL Compatible Null Handling +By default, Druid string dimension columns use the values `''` and `null` interchangeably and numeric and metric columns can not represent `null` at all, instead coercing nulls to `0`. However, Druid also provides an SQL compatible null handling mode, which must be enabled at the system level, through `druid.generic.useDefaultValueForNull`. This setting, when set to `false`, will allow Druid to _at ingestion time_ create segments whose string columns can distinguish `''` from `null`, and numeric columns which can represent `null` valued rows instead of `0`. Review comment:  but fine I will change all occurrences that I added 😛 ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
