Re: Thousands of parallel connections

Tom Lane wrote:

>Chris Travers <chris(at)metatrontech(dot)com> writes:
>
>
>>Tom Lane wrote:
>>
>>
>>>That does not add up: the graph can't have a negative y-intercept.
>>>There should be a substantial cost to run the postmaster at all,
>>>and then an essentially fixed cost per connection --- assuming
>>>that all the connections are running similar queries, of course.
>>>You're telling us the first 40 connections require zero RAM.
>>>
>>>
>
>
>
>>That is strange. Is it really linear or does the cost go up somewhat
>>after the first few?
>>
>>
>
>Well, if you have significant contention problems then the speed could
>be worse than linear --- but he was talking about memory usage. AFAICS,
>a backend doing a particular query should need X amount of RAM pretty
>much independently of how many others there are. The only data structure
>I can think of that would be impacted at all is QuerySnapshot, and at
>4 bytes per sibling backend it's *way* down in the noise...
>
> regards, tom lane
>
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Then my final question is whether part of the issue could be increased
shared memory and other performance related settings in order to
gracefully handle the larger number of connections.

Best Wishes,
Chris Travers
Metatron Technology Consulting