Select queries
Older versions of Apache Druid included a Select query type. Since Druid 0.17.0, it has been removed and replaced by the Scan query, which offers improved memory usage and performance. This solves issues that users had with Select queries causing Druid to run out of memory or slow down.
The Scan query has a different syntax, but supports many of the features of the Select query, including time ordering and limiting. Scan does not include the Select query's pagination feature; however, in many cases pagination is unnecessary with Scan due to its ability to return a virtually unlimited number of results in one call.