https://community.cloudera.com/t5/Support-Questions/Hive-concurrency-lost-update/m-p/335613#M231987 <P>Hi, I am seeing some situations where I have two Hive SQL commands running concurrently and I'm getting a lost update.&nbsp; I am running Hive 2.3.6 on EMR with hive.support.concurrency = true and I believe this shouldn't be happening based on what I understand about Hive table locking.&nbsp; (I am not using ACID transactions but the table locking should still prevent lost update as far as I know;)</P><P>&nbsp;</P><P>Specifically I have a "load data" statement loading data into table T from an S3 location.&nbsp; I have an "insert overwrite T select * from T" table running concurrently from another Hive connection that deletes some rows from T but should not be affecting rows from the load data statement.&nbsp; I am seeing that the data from the load data statement disappears after the insert overwrite finishes.&nbsp; My understanding is that the load data and insert overwrite should create an exclusive table lock on T so they should allow each other to finish before reading or writing data from T.&nbsp; (I checked this using "show locks" and they do definitely create an exclusive lock.)</P><P>&nbsp;</P><P>&nbsp;</P><P>Has anyone seen this issue before and are there any Hive settings I can try changing to prevent this behavior?</P> Thu, 03 Feb 2022 22:27:35 GMT KFredrickson 2022-02-03T22:27:35Z https://community.cloudera.com/t5/Support-Questions/Hive-concurrency-lost-update/m-p/335613#M231987 <P>Hi, I am seeing some situations where I have two Hive SQL commands running concurrently and I'm getting a lost update.&nbsp; I am running Hive 2.3.6 on EMR with hive.support.concurrency = true and I believe this shouldn't be happening based on what I understand about Hive table locking.&nbsp; (I am not using ACID transactions but the table locking should still prevent lost update as far as I know;)</P><P>&nbsp;</P><P>Specifically I have a "load data" statement loading data into table T from an S3 location.&nbsp; I have an "insert overwrite T select * from T" table running concurrently from another Hive connection that deletes some rows from T but should not be affecting rows from the load data statement.&nbsp; I am seeing that the data from the load data statement disappears after the insert overwrite finishes.&nbsp; My understanding is that the load data and insert overwrite should create an exclusive table lock on T so they should allow each other to finish before reading or writing data from T.&nbsp; (I checked this using "show locks" and they do definitely create an exclusive lock.)</P><P>&nbsp;</P><P>&nbsp;</P><P>Has anyone seen this issue before and are there any Hive settings I can try changing to prevent this behavior?</P> Thu, 03 Feb 2022 22:27:35 GMT https://community.cloudera.com/t5/Support-Questions/Hive-concurrency-lost-update/m-p/335613#M231987 KFredrickson 2022-02-03T22:27:35Z https://community.cloudera.com/t5/Support-Questions/Hive-concurrency-lost-update/m-p/335690#M232003 <P>This was a result of a bug in my code and not anything to do with Hive itself - please ignore.</P> Sun, 06 Feb 2022 10:30:59 GMT https://community.cloudera.com/t5/Support-Questions/Hive-concurrency-lost-update/m-p/335690#M232003 KFredrickson 2022-02-06T10:30:59Z