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https://issues.apache.org/jira/browse/IMPALA-8266?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vihang Karajgaonkar resolved IMPALA-8266.
-----------------------------------------
Resolution: Fixed
Fix Version/s: Impala 3.2.0
> Event filtering logic may not filter all the events
> ---------------------------------------------------
>
> Key: IMPALA-8266
> URL: https://issues.apache.org/jira/browse/IMPALA-8266
> Project: IMPALA
> Issue Type: Sub-task
> Reporter: Vihang Karajgaonkar
> Assignee: Vihang Karajgaonkar
> Priority: Major
> Fix For: Impala 3.2.0
>
>
> Here is a the logic to filter out create events from a given batch of events.
> {code}
> Iterator<MetastoreEvent> it = metastoreEvents.iterator();
> // filter out the create events which has a corresponding drop event
> later
> int fromIndex = 0;
> int numFilteredEvents = 0;
> int inputSize = metastoreEvents.size();
> while (it.hasNext()) {
> MetastoreEvent current = it.next();
> if (fromIndex < metastoreEvents.size() && current.isRemovedAfter(
> metastoreEvents.subList(fromIndex + 1, metastoreEvents.size()))) {
> LOG.info(current.debugString("Filtering out this event since the
> object is "
> + "either removed or renamed later in the event stream"));
> it.remove();
> numFilteredEvents++;
> }
> fromIndex++;
> }
> {code}
> If the event list contains CREATE_DATABASE, CREATE_TABLE, DROP_TABLE,
> DROP_DATABASE events, it is possible that we only filter out CREATE_DATABASE
> event and not CREATE_TABLE event. This is because the {{fromIndex}} above
> gets incremented event iteration of the {{while}} loop and hence when it is
> evaluating if there is a inverse event later on in the stream, it starts to
> look from DROP_DATABASE event onwards.
> The fix is simple, the fromIndex needs to be incremented only when the item
> from the list is not removed.
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