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From Denis Magda <dma...@apache.org>
Subject Re: delete is too slow, sometimes even causes OOM
Date Tue, 03 Nov 2020 16:08:19 GMT
Hi Frank,

Thanks for starting this discussion. Our contributors with SQL experience
should step in.

Generally, I came across this performance issue a week or so ago while
doing training about Ignite. In my case, a simple DELETE was running for a
minute over a table of negligible size.

-
Denis


On Tue, Nov 3, 2020 at 7:53 AM frank li <frankli22568@gmail.com> wrote:

> Current code logic for DELETE is as follows:
> if WHERE clause contains a condition as "key=xxx", it uses fastUpdate
> which remove the related item directly.
>
> else
>     do select for update;
>     for each row, call closure code "RMV" to remove it.
>
> 1. As "executeSelectForDml" get _KEY and _VAL columns for all condidate
> rows, it often causes OOM when there are a lot of data  to delete. Why do
> we verify "val" during remove operation?
>
> 2. After selection,  why don't we just remove it with cache.remove as
> fastUpdate does?
>
>
>

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