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| <title>RUNTIME_FILTER_MODE Query Option (Impala 2.5 or higher only)</title> |
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| <h1 class="title topictitle1" id="ariaid-title1">RUNTIME_FILTER_MODE Query Option (<span class="keyword">Impala 2.5</span> or higher only)</h1> |
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| <p class="p"> |
| The <code class="ph codeph">RUNTIME_FILTER_MODE</code> query option |
| adjusts the settings for the runtime filtering feature. |
| It turns this feature on and off, and controls how |
| extensively the filters are transmitted between hosts. |
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| <strong class="ph b">Type:</strong> numeric (0, 1, 2) |
| or corresponding mnemonic strings (<code class="ph codeph">OFF</code>, <code class="ph codeph">LOCAL</code>, <code class="ph codeph">GLOBAL</code>). |
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| <strong class="ph b">Default:</strong> 2 (equivalent to <code class="ph codeph">GLOBAL</code>); formerly was 1 / <code class="ph codeph">LOCAL</code>, in <span class="keyword">Impala 2.5</span> |
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| <p class="p"> |
| <strong class="ph b">Added in:</strong> <span class="keyword">Impala 2.5.0</span> |
| </p> |
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| <p class="p"> |
| <strong class="ph b">Usage notes:</strong> |
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| In <span class="keyword">Impala 2.6</span> and higher, the default is <code class="ph codeph">GLOBAL</code>. |
| This setting is recommended for a wide variety of workloads, to provide best |
| performance with <span class="q">"out of the box"</span> settings. |
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| <p class="p"> |
| The lowest setting of <code class="ph codeph">LOCAL</code> does a similar level of optimization |
| (such as partition pruning) as in earlier Impala releases. |
| This setting was the default in <span class="keyword">Impala 2.5</span>, |
| to allow for a period of post-upgrade testing for existing workloads. |
| This setting is suitable for workloads with non-performance-critical queries, |
| or if the coordinator node is under heavy CPU or memory pressure. |
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| <p class="p"> |
| You might change the setting to <code class="ph codeph">OFF</code> if your workload contains |
| many queries involving partitioned tables or joins that do not experience a performance |
| increase from the runtime filters feature. If the overhead of producing the runtime filters |
| outweighs the performance benefit for queries, you can turn the feature off entirely. |
| </p> |
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| <p class="p"> |
| <strong class="ph b">Related information:</strong> |
| </p> |
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| <p class="p"> |
| <a class="xref" href="impala_partitioning.html#partitioning">Partitioning for Impala Tables</a> for details about runtime filtering. |
| <a class="xref" href="impala_disable_row_runtime_filtering.html#disable_row_runtime_filtering">DISABLE_ROW_RUNTIME_FILTERING Query Option (Impala 2.5 or higher only)</a>, |
| <a class="xref" href="impala_runtime_bloom_filter_size.html#runtime_bloom_filter_size">RUNTIME_BLOOM_FILTER_SIZE Query Option (Impala 2.5 or higher only)</a>, |
| <a class="xref" href="impala_runtime_filter_wait_time_ms.html#runtime_filter_wait_time_ms">RUNTIME_FILTER_WAIT_TIME_MS Query Option (Impala 2.5 or higher only)</a>, |
| and |
| <a class="xref" href="impala_max_num_runtime_filters.html#max_num_runtime_filters">MAX_NUM_RUNTIME_FILTERS Query Option (Impala 2.5 or higher only)</a> |
| for tuning options for runtime filtering. |
| </p> |
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| </div> |
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| <div class="related-links"> |
| <div class="familylinks"> |
| <div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_query_options.html">Query Options for the SET Statement</a></div> |
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