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https://issues.apache.org/jira/browse/IMPALA-10468?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vihang Karajgaonkar updated IMPALA-10468:
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Issue Type: Bug (was: Improvement)
> DROP events which are generated while a batch is being processed may add
> table incorrectly
> ------------------------------------------------------------------------------------------
>
> Key: IMPALA-10468
> URL: https://issues.apache.org/jira/browse/IMPALA-10468
> Project: IMPALA
> Issue Type: Bug
> Reporter: Vihang Karajgaonkar
> Assignee: Vihang Karajgaonkar
> Priority: Major
>
> One of the problems with CREATE/DROP events is that they may occur while a
> batch is being processed and hence EventsProcessor may not able aware of that.
> For example, consider the following sequence of statements:
> create table foo (c1 int);
> drop table foo;
> create table foo (c2 int);
> drop table foo;
> These statements will generate CREATE_TABLE, DROP_TABLE, CREATE_TABLE,
> DROP_TABLE event sequence. Generally, if all these 4 events are fetched in a
> batch, then the first CREATE_TABLE and third CREATE_TABLE is ignored because
> it is followed by the a DROP_TABLE in the sequence and the DROP_TABLE events
> take no effect since the table doesn't exist in catalogd anymore.
> However, if the events processor fetches these events in 2 batches (3 and 1)
> then after the first batch of CREATE_TABLE, DROP_TABLE, CREATE_TABLE is
> processed, the third event will add the table foo in the catalogd. The
> subsequent batch's DROP_TABLE will be processed and remove the table, but
> between the two batches, catalogd will say that a table called foo exists.
> This can lead to statements getting errored out. Eg. a statement like create
> table foo (c3 int) after the above statements will error out with a
> TableAlreadyExists error.
> The problem happens for databases too. So far I have not been able to
> reproduce this for Partitions but I don't see why it will not happen with
> Partitions also.
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