Re: [HACKERS] UPDATE of partition key

On 16 January 2018 at 09:17, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> wrote:
> On 16 January 2018 at 01:09, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> On Sun, Jan 14, 2018 at 6:57 AM, Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com> wrote:
>>> Even where partitions are present, in the usual case where there are
>>> Instead of a bool array, we can even make it a Bitmapset. But I think
>>> access would become slower as compared to array, particularly because
>>> it is going to be a heavily used function.
>>
>> It probably makes little difference -- the Bitmapset will be more
>> compact (which saves time) but involve function calls (which cost
>> time).
>
> I'm not arguing in either direction, but you'd also want to factor in
> how Bitmapsets only allocate words for the maximum stored member,
> which might mean multiple realloc() calls resulting in palloc/memcpy
> calls. The array would just be allocated in a single chunk, although
> it would be more memory and would require a memset too, however,
> that's likely much cheaper than the palloc() anyway.

Right. I agree. And also a function call for knowing whether required
or not. Overall, I think especially because the data structure will be
used heavily whenever it is set up, it's better to make it an array.
In the latest patch, I have retained it as an array

--
Thanks,
-Amit Khandekar
EnterpriseDB Corporation
The Postgres Database Company