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Posted to issues@calcite.apache.org by "hqx (Jira)" <ji...@apache.org> on 2021/03/04 13:32:00 UTC
[jira] [Updated] (CALCITE-4522) optimize sort cost formula
[ https://issues.apache.org/jira/browse/CALCITE-4522?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
hqx updated CALCITE-4522:
-------------------------
Description:
The old method to compute the cost of sort has some problem.
# when there is no need to sort, it still to compute the cpu cost of sort.
# use n * log(n)rowBytes to estimate the cpu cost may be inaccurate, where n means the output row count of the sort operator, and rowBytes means the average bytes of one row .
Instead, I give follow suggestion.
# the cpu cost is zero if there is no need to sort.
# use m * log(n) rowBytes to compute the cpu cost, where m is the sum of offset + limit and n means input row count.
was:
The old method to compute the cost of sort has some problem.
# when there is no need to sort, it still to compute the cpu cost of sort.
# use n * log(n) rowBytes to estimate the cpu cost may be inaccurate, where n means the output row count of the sort operator, and rowBytes means the average bytes of one row .
Instead, I give follow suggestion.
# the cpu cost is zero if there is no need to sort.
# use m * log(n) rowBytes to compute the cpu cost, where m is the sum of offset + limit and n means input row count.
> optimize sort cost formula
> --------------------------
>
> Key: CALCITE-4522
> URL: https://issues.apache.org/jira/browse/CALCITE-4522
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: hqx
> Priority: Minor
>
> The old method to compute the cost of sort has some problem.
> # when there is no need to sort, it still to compute the cpu cost of sort.
> # use n * log(n)rowBytes to estimate the cpu cost may be inaccurate, where n means the output row count of the sort operator, and rowBytes means the average bytes of one row .
> Instead, I give follow suggestion.
> # the cpu cost is zero if there is no need to sort.
> # use m * log(n) rowBytes to compute the cpu cost, where m is the sum of offset + limit and n means input row count.
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