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| <!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
| <concept rev="2.3.0" id="live_summary"> |
| |
| <title>LIVE_SUMMARY Query Option (<keyword keyref="impala23"/> or higher only)</title> |
| <titlealts audience="PDF"><navtitle>LIVE_SUMMARY</navtitle></titlealts> |
| <prolog> |
| <metadata> |
| <data name="Category" value="Impala"/> |
| <data name="Category" value="Impala Query Options"/> |
| <data name="Category" value="Querying"/> |
| <data name="Category" value="Performance"/> |
| <data name="Category" value="Reports"/> |
| <data name="Category" value="impala-shell"/> |
| <data name="Category" value="Developers"/> |
| <data name="Category" value="Data Analysts"/> |
| </metadata> |
| </prolog> |
| |
| <conbody> |
| <p rev="2.3.0"> When the <codeph>LIVE_SUMMARY</codeph> query option is set |
| to <codeph>TRUE</codeph>, Impala displays the same output as the |
| <codeph>SUMMARY</codeph> command for queries submitted through the |
| <cmdname>impala-shell</cmdname> command, with the measurements updated |
| in real time as the query progresses. When the query finishes, the final |
| <codeph>SUMMARY</codeph> output remains visible in the |
| <cmdname>impala-shell</cmdname> console output. </p> |
| <p>Starting in <keyword keyref="impala31"/>, the summary output also |
| includes the queuing status consisting of whether the query was queued and |
| what was the latest queuing reason.</p> |
| <p><b>Type:</b> |
| <codeph>Boolean</codeph></p> |
| <p><b>Default:</b> |
| <codeph>FALSE (0)</codeph></p> |
| <p conref="../shared/impala_common.xml#common/command_line_blurb"/> |
| <p> You can enable this query option within <cmdname>impala-shell</cmdname> |
| by starting the shell with the <codeph>--live_summary</codeph> |
| command-line option. You can still turn this setting off and on again |
| within the shell through the <codeph>SET</codeph> command. </p> |
| <p conref="../shared/impala_common.xml#common/usage_notes_blurb"/> |
| <p> The live summary output can be useful for evaluating long-running |
| queries, to evaluate which phase of execution takes up the most time, or |
| if some hosts take much longer than others for certain operations, |
| dragging overall performance down. By making the information available in |
| real time, this feature lets you decide what action to take even before |
| you cancel a query that is taking much longer than normal. </p> |
| <p> For example, you might see the HDFS scan phase taking a long time, and |
| therefore revisit performance-related aspects of your schema design such |
| as constructing a partitioned table, switching to the Parquet file format, |
| running the <codeph>COMPUTE STATS</codeph> statement for the table, and so |
| on. Or you might see a wide variation between the average and maximum |
| times for all hosts to perform some phase of the query, and therefore |
| investigate if one particular host needed more memory or was experiencing |
| a network problem. </p> |
| <p conref="../shared/impala_common.xml#common/live_reporting_details"/> |
| <p> For a simple and concise way of tracking the progress of an interactive |
| query, see <xref href="impala_live_progress.xml#live_progress"/>. </p> |
| <p conref="../shared/impala_common.xml#common/restrictions_blurb"/> |
| <p |
| conref="../shared/impala_common.xml#common/impala_shell_progress_reports_compute_stats_caveat"/> |
| <p |
| conref="../shared/impala_common.xml#common/impala_shell_progress_reports_shell_only_caveat"/> |
| <p conref="../shared/impala_common.xml#common/added_in_230"/> |
| <p |
| conref="../shared/impala_common.xml#common/live_progress_live_summary_asciinema" |
| /> |
| </conbody> |
| </concept> |