[ https://issues.apache.org/jira/browse/HIVE-7469?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
wangmeng updated HIVE-7469: --------------------------- Description: In https://issues.apache.org/jira/browse/HIVE-964, I have a general idea about how to deal with skew join key , the key point is that use mapjoin to deal with skew key, but there has a case which troubles me: if the two join tables have the same big skew key on one value : for example , select * from table A join B on A.id=b.id, both table A and B have a lot of keys on id=1, in this case , if we use map join to deal with the skew key id=1 ,maybe it will OOM. so ,how to fix this case? Will it rollback to common join ? Thanks. was: In https://issues.apache.org/jira/browse/HIVE-964, I have a general idea about how to deal with skew join key , the key is that use mapjoin to deal with skew key, but there has a case which troubles me: if the two join tables have the same big skew key on one value : for example , select * from table A join B on A.id=b.id, both table A and B have a lot of keys on id=1, in this case , if we use map join to deal with the skew key id=1 ,maybe it will OOM. so ,how to fix this case? Will it rollback to common join ? Thanks. > skew join keys when two join table have the same big skew key > ----------------------------------------------------------------- > > Key: HIVE-7469 > URL: https://issues.apache.org/jira/browse/HIVE-7469 > Project: Hive > Issue Type: Improvement > Reporter: wangmeng > > In https://issues.apache.org/jira/browse/HIVE-964, I have a general idea > about how to deal with skew join key , the key point is that use mapjoin > to deal with skew key, but there has a case which troubles me: > if the two join tables have the same big skew key on one value : > for example , select * from table A join B on A.id=b.id, both table A > and B have a lot of keys on id=1, in this case , if we use map join > to deal with the skew key id=1 ,maybe it will OOM. > so ,how to fix this case? Will it rollback to common join ? Thanks. -- This message was sent by Atlassian JIRA (v6.2#6252)