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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="node_blacklisting">
<title>Impala Node Blacklisting</title>
<conbody>
<p>Node Blacklisting allows Impala Coordinators to be more aggressive
about deciding that an executor is unhealthy or unavailable, to
minimize failed queries in environments where cluster membership maybe
more variable, rather than having to wait on the statestore heartbeat
mechanism to decide that the executor is down.</p>
<p>Node blacklists are local to a coordinator. A node is put on the
blacklist based on information from failed queries. Nodes are only
blacklisted temporarily, and are taken off the blacklist after a
certain period of time.</p>
</conbody>
</concept>