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   <h1 class="title topictitle1" id="ariaid-title1">THREAD_RESERVATION_AGGREGATE_LIMIT Query Option (<span class="keyword">Impala 3.1</span> or higher only)</h1>


   <div class="body conbody">

     <p class="p">
       The <code class="ph codeph">THREAD_RESERVATION_AGGREGATE_LIMIT</code> query option limits the number of
       reserved threads for a query across all nodes on which it is executing. The option is
       intended to prevent execution of complex queries that can consume excessive CPU or
       operating system resources on a cluster. Queries that have more threads than this
       threshold are rejected by Impala’s admission controller before they start executing.
     </p>


     <p class="p">
       For example, an Impala administrator could set a default value of
       <code class="ph codeph">THREAD_RESERVATION_AGGREGATE_LIMIT=2000</code> for a resource pool on a 100 node
       where they expect only relatively simple queries with less than 20 threads per node to
       run. This will reject queries that require more than 2000 reserved threads across all
       nodes, for example a query with 21 fragments running on all 100 nodes of the cluster.
     </p>


     <p class="p">
       You can override the default value per-query or per-session, in the same way as other
       query options, if you do not want the default
       <code class="ph codeph">THREAD_RESERVATION_AGGREGATE_LIMIT</code> value to apply to a specific query or
       session.
     </p>


     <p class="p">
       <strong class="ph b">Syntax:</strong> <code class="ph codeph">SET THREAD_RESERVATION_AGGREGATE_LIMIT=number;</code>
     </p>


     <p class="p">
       <strong class="ph b">Type:</strong> numeric
     </p>


     <p class="p">
       <strong class="ph b">Default:</strong> 0 (no limit)
     </p>


     <p class="p">
       <strong class="ph b">Added in:</strong> <span class="keyword">Impala 3.1</span>
     </p>


   </div>


 <div class="related-links">
 <div class="familylinks">
 <div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_set.html">SET Statement</a></div>
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	<title>THREAD_RESERVATION_AGGREGATE_LIMIT Query Option (Impala 3.1 or higher only)</title>
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	<body id="thread_reservation_aggregate_limit">


	<h1 class="title topictitle1" id="ariaid-title1">THREAD_RESERVATION_AGGREGATE_LIMIT Query Option (<span class="keyword">Impala 3.1</span> or higher only)</h1>






	<div class="body conbody">

	<p class="p">
	The <code class="ph codeph">THREAD_RESERVATION_AGGREGATE_LIMIT</code> query option limits the number of
	reserved threads for a query across all nodes on which it is executing. The option is
	intended to prevent execution of complex queries that can consume excessive CPU or
	operating system resources on a cluster. Queries that have more threads than this
	threshold are rejected by Impala’s admission controller before they start executing.
	</p>


	<p class="p">
	For example, an Impala administrator could set a default value of
	<code class="ph codeph">THREAD_RESERVATION_AGGREGATE_LIMIT=2000</code> for a resource pool on a 100 node
	where they expect only relatively simple queries with less than 20 threads per node to
	run. This will reject queries that require more than 2000 reserved threads across all
	nodes, for example a query with 21 fragments running on all 100 nodes of the cluster.
	</p>


	<p class="p">
	You can override the default value per-query or per-session, in the same way as other
	query options, if you do not want the default
	<code class="ph codeph">THREAD_RESERVATION_AGGREGATE_LIMIT</code> value to apply to a specific query or
	session.
	</p>


	<p class="p">
	<strong class="ph b">Syntax:</strong> <code class="ph codeph">SET THREAD_RESERVATION_AGGREGATE_LIMIT=number;</code>
	</p>


	<p class="p">
	<strong class="ph b">Type:</strong> numeric
	</p>


	<p class="p">
	<strong class="ph b">Default:</strong> 0 (no limit)
	</p>


	<p class="p">
	<strong class="ph b">Added in:</strong> <span class="keyword">Impala 3.1</span>
	</p>


	</div>


	<div class="related-links">
	<div class="familylinks">
	<div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_set.html">SET Statement</a></div>
	</div>
	</div></body>
	</html>