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https://issues.apache.org/jira/browse/HAWQ-975?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15451831#comment-15451831
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Chunling Wang edited comment on HAWQ-975 at 8/31/16 10:30 AM:
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The performance of explain analyze on AWS is low because the VDSO on agents of
AWS is not properly configured and does not work well. To be specific,
gettimeofday() takes too much time.
was (Author: wcl14):
It is because that the VDSO on agents of AWS does not work well. So the
execution time of function 'gettimeofday()' is too much.
> Queries run much slower with 'explain analyze' than which without 'explain
> analyze'
> ------------------------------------------------------------------------------------
>
> Key: HAWQ-975
> URL: https://issues.apache.org/jira/browse/HAWQ-975
> Project: Apache HAWQ
> Issue Type: Bug
> Components: Core
> Reporter: Chunling Wang
> Assignee: Chunling Wang
> Priority: Critical
> Labels: performance
> Fix For: 2.0.1.0-incubating
>
>
> When we run queries with 'explain analyze' in AWS cluster, the total running
> time is about 2-3 times longer than which without 'explain analyze'.
> Here is a group of TPC-H results for queries with 'explain analyze' and
> queries without 'explain analyze'.
> ||query ||without 'explain analyze' ||with 'explain analyze'
> ||multiple
> |TPCH_Query_01 | 311843 | 818658 | 2.63
> |TPCH_Query_02 | 34675 | 117884 | 3.40
> |TPCH_Query_03 | 166155 | 422131 | 2.54
> |TPCH_Query_04 | 157807 | 507143 | 3.21
> |TPCH_Query_05 | 272657 | 710573 | 2.61
> |TPCH_Query_06 | 12508 | 22276 | 1.78
> |TPCH_Query_07 | 71893 | 370338 | 5.15
> |TPCH_Query_08 | 129999 | 672625 | 5.17
> |TPCH_Query_09 | 575709 | 1171672 | 2.04
> |TPCH_Query_10 | 93770 | 233391 | 2.49
> |TPCH_Query_11 | 16252 | 58360 | 3.59
> |TPCH_Query_12 | 142576 | 237270 | 1.66
> |TPCH_Query_13 | 72682 | 343257 | 4.72
> |TPCH_Query_14 | 10410 | 32337 | 3.11
> |TPCH_Query_15 | 25719 | 98705 | 3.84
> |TPCH_Query_16 | 21382 | 76877 | 3.60
> |TPCH_Query_17 | 839683 | 2041169 | 2.43
> |TPCH_Query_18 | 460570 | 1065940 | 2.31
> |TPCH_Query_19 | 69075 | 82286 | 1.19
> |TPCH_Query_20 | 78263 | 292041 | 3.73
> |TPCH_Query_21 | 505606 | 1549690 | 3.07
> |TPCH_Query_22 | 56450 | 329837 | 5.84
> |Total | 4125684 | 11254460 |
> 2.73
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