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| <!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
| <concept id="runtime_filter_mode" rev="2.5.0"> |
| |
| <title>RUNTIME_FILTER_MODE Query Option (<keyword keyref="impala25"/> or higher only)</title> |
| <titlealts audience="PDF"><navtitle>RUNTIME_FILTER_MODE</navtitle></titlealts> |
| <prolog> |
| <metadata> |
| <data name="Category" value="Impala"/> |
| <data name="Category" value="Impala Query Options"/> |
| <data name="Category" value="Performance"/> |
| <data name="Category" value="Developers"/> |
| <data name="Category" value="Data Analysts"/> |
| </metadata> |
| </prolog> |
| |
| <conbody> |
| |
| <p rev="2.5.0"> |
| <indexterm audience="hidden">RUNTIME_FILTER_MODE query option</indexterm> |
| </p> |
| |
| <p> |
| The <codeph>RUNTIME_FILTER_MODE</codeph> 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. |
| </p> |
| |
| <p> |
| <b>Type:</b> numeric (0, 1, 2) |
| or corresponding mnemonic strings (<codeph>OFF</codeph>, <codeph>LOCAL</codeph>, <codeph>GLOBAL</codeph>). |
| </p> |
| |
| <p rev="2.6.0"> |
| <b>Default:</b> 2 (equivalent to <codeph>GLOBAL</codeph>); formerly was 1 / <codeph>LOCAL</codeph>, in <keyword keyref="impala25_full"/> |
| </p> |
| |
| <p conref="../shared/impala_common.xml#common/added_in_250"/> |
| |
| <p conref="../shared/impala_common.xml#common/usage_notes_blurb"/> |
| |
| <p rev="2.6.0"> |
| In <keyword keyref="impala26_full"/> and higher, the default is <codeph>GLOBAL</codeph>. |
| This setting is recommended for a wide variety of workloads, to provide best |
| performance with <q>out of the box</q> settings. |
| </p> |
| |
| <p rev="2.6.0"> |
| The lowest setting of <codeph>LOCAL</codeph> does a similar level of optimization |
| (such as partition pruning) as in earlier Impala releases. |
| This setting was the default in <keyword keyref="impala25_full"/>, |
| 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. |
| </p> |
| |
| <p> |
| You might change the setting to <codeph>OFF</codeph> 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> |
| |
| <p conref="../shared/impala_common.xml#common/related_info"/> |
| <p> |
| <xref href="impala_partitioning.xml#partitioning"/> for details about runtime filtering. |
| <xref href="impala_disable_row_runtime_filtering.xml#disable_row_runtime_filtering"/>, |
| <xref href="impala_runtime_bloom_filter_size.xml#runtime_bloom_filter_size"/>, |
| <xref href="impala_runtime_filter_wait_time_ms.xml#runtime_filter_wait_time_ms"/>, |
| and |
| <xref href="impala_max_num_runtime_filters.xml#max_num_runtime_filters"/> |
| for tuning options for runtime filtering. |
| </p> |
| |
| </conbody> |
| </concept> |