rule: parallelize projects calling UAST not under exchanges #767
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kuba--
reviewed
Mar 29, 2019
| return nil, io.EOF | ||
| } | ||
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| if i.rows == nil { |
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I think we need to wrap this if by mutex
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Nope, Next is never used in parallel
Fixes #766 Since rows are iterated serially (except for exchange nodes), when a Project node calls UAST, it's processed one at a time, which underutilizes the resources in the machine. When a Project calls UAST or UAST_MODE and is not under an Exchange node, which already parallelizes its children, replaces the project with a special node called parallelProject, which is essentially a project that keeps up to N goroutines processing rows, where N is the parallelism value of gitbase. Signed-off-by: Miguel Molina <miguel@erizocosmi.co>
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Should be passing now |
kuba--
approved these changes
Apr 2, 2019
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Let's keep this on pause after the new fixed RC |
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@erizocosmico Does the parallel project alter row order? If it does, it can give wrong results if ran after an ORDER BY. |
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@smola yes, you're right. It needs to check if it has an order by underneath and not execute it in parallel in that case or return the rows in the same order. |
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Fixes #766
Since rows are iterated serially (except for exchange nodes), when
a Project node calls UAST, it's processed one at a time, which
underutilizes the resources in the machine.
When a Project calls UAST or UAST_MODE and is not under an Exchange
node, which already parallelizes its children, replaces the project
with a special node called parallelProject, which is essentially a
project that keeps up to N goroutines processing rows, where N is
the parallelism value of gitbase.
Signed-off-by: Miguel Molina miguel@erizocosmi.co