https://community.cloudera.com/t5/Support-Questions/Reading-a-Hive-table-while-doing-insert-overwrite-on-a/m-p/220361#M182246 <A rel="user" href="https://community.cloudera.com/users/16119/viswanathkammula.html" nodeid="16119">@viswanath</A><P>For a partitioned table, the idea is as follows:</P><P>A 'S' lock on table and relevant partition is acquired when a read is being performed. For all other operations, an 'X' lock is taken on the partition. However, if the change is only applicable to the newer partitions, a 'S' lock is acquired on the table, whereas if the change is applicable to all partitions, a 'X' lock is acquired on the table. Thus, older partitions can be read and written into, while the newer partitions are being converted to RCFile. Whenever a partition is being locked in any mode, all its parents are locked in 'S' mode.</P><P>If you are running 'select' query on the whole of table, then it would wait for the exclusive lock.</P><P>For more details, refer to <A href="https://cwiki.apache.org/confluence/display/Hive/Locking">link</A>.</P><A rel="user" href="https://community.cloudera.com/users/16119/viswanathkammula.html" nodeid="16119"></A> Sat, 14 Oct 2017 15:16:08 GMT ssubhas 2017-10-14T15:16:08Z