Re: coverage increase for worker_spi

On 2019-May-30, Tom Lane wrote:

> Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> > On 2019-May-29, Tom Lane wrote:
> >> I'm not opposed to adding a new test case at this point in the cycle,
> >> but as written this one seems more or less guaranteed to fail under
> >> load.
> 
> > True.  Here's a version that should be more resilient.
> 
> Hm, I don't understand how this works at all:
> 
> +			PERFORM pg_sleep(CASE WHEN count(*) = 0 THEN 0 ELSE 0.1 END)
> +			FROM schema1.counted WHERE type = 'delta';
> +			GET DIAGNOSTICS count = ROW_COUNT;
> 
> Given that it uses an aggregate, the ROW_COUNT must always be 1, no?

Well, I was surprised to see the count(*) work there as an argument for
pg_sleep there at all frankly (maybe we are sleeping 0.1s more than we
really need, per your observation), but the row_count is concerned with
rows that have type = 'delta', which are deleted by the bgworker.  So
the test script job is done when the bgworker has run once through its
loop.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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