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https://issues.apache.org/jira/browse/IMPALA-1306?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tim Armstrong reassigned IMPALA-1306:
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Assignee: (was: Marcel Kinard)
> Avoid passing (empty) tuples of non-materialized slots, if consumer does not
> need them
> --------------------------------------------------------------------------------------
>
> Key: IMPALA-1306
> URL: https://issues.apache.org/jira/browse/IMPALA-1306
> Project: IMPALA
> Issue Type: Improvement
> Components: Frontend
> Affects Versions: Impala 1.4.1
> Reporter: Ippokratis Pandis
> Priority: Minor
> Labels: planner
>
> In case of non-materialized slots we should not producing tuples
> for those slots, if it is the only slot in the tuple and the consumer
> node(s) do not need them. For example, in the query below nodes 03:ANALYTIC
> and 06:EXCHANGE should not have tuple_id=1.
> This has some impact in perf of BE, as in many codepaths we iterate over all
> the tuples in the row.
> {code}
> [localhost:21000] > explain select AVG(t1.int_col) OVER () FROM alltypestiny
> t1 WHERE EXISTS (SELECT t1.month FROM alltypestiny t1);
> Query: explain select AVG(t1.int_col) OVER () FROM alltypestiny t1 WHERE
> EXISTS (SELECT t1.month FROM alltypestiny t1)
> +----------------------------------------------------------+
> | Explain String |
> +----------------------------------------------------------+
> | Estimated Per-Host Requirements: Memory=64.00MB VCores=2 |
> | |
> | 03:ANALYTIC |
> | | functions: avg(t1.int_col) |
> | | hosts=3 per-host-mem=unavailable |
> | | tuple-ids=0,1,6 row-size=12B cardinality=8 |
> | | |
> | 06:EXCHANGE [UNPARTITIONED] |
> | | hosts=3 per-host-mem=unavailable |
> | | tuple-ids=0,1 row-size=4B cardinality=8 |
> | | |
> | 02:CROSS JOIN [BROADCAST] |
> | | hosts=3 per-host-mem=0B |
> | | tuple-ids=0,1 row-size=4B cardinality=8 |
> | | |
> | |--05:EXCHANGE [BROADCAST] |
> | | | hosts=3 per-host-mem=0B |
> | | | tuple-ids=1 row-size=0B cardinality=1 |
> | | | |
> | | 04:EXCHANGE [UNPARTITIONED] |
> | | | limit: 1 |
> | | | hosts=3 per-host-mem=unavailable |
> | | | tuple-ids=1 row-size=0B cardinality=1 |
> | | | |
> | | 01:SCAN HDFS [functional.alltypestiny t1, RANDOM] |
> | | partitions=4/4 size=460B |
> | | table stats: 8 rows total |
> | | column stats: all |
> | | limit: 1 |
> | | hosts=3 per-host-mem=32.00MB |
> | | tuple-ids=1 row-size=0B cardinality=1 |
> | | |
> | 00:SCAN HDFS [functional.alltypestiny t1, RANDOM] |
> | partitions=4/4 size=460B |
> | table stats: 8 rows total |
> | column stats: all |
> | hosts=3 per-host-mem=32.00MB |
> | tuple-ids=0 row-size=4B cardinality=8 |
> +----------------------------------------------------------+
> {code}
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