Re: more detailed description of tup_returned and tup_fetched

On 2021/05/20 17:38, Masahiro Ikeda wrote:
>
>
> On 2021/05/20 17:00, Fujii Masao wrote:
>> On 2021/05/20 9:46, Masahiro Ikeda wrote:
>>> On 2021/05/18 20:10, Fujii Masao wrote:
>>>>>> pg_stat_database.tup_fetched:
>>>>>> Number of index entries returned by scans on indexes in this database
>>>>> Is this the sum of pg_stat_all_indexes.idx_tup_read? This is accounted to
>>>>> pg_stat_database.tup_returned.
>>>>
>>>> I was thinking that pg_stat_database.tup_fetched is the same as
>>>> the sum of pg_stat_all_tables.idx_tup_fetch. Because they both
>>>> are incremented by bitmap index scans, but pg_stat_all_indexes.idx_tup_read
>>>> is not.
>>>
>>> Yes. So, "Number of index entries returned by scans on indexes in this
>>> database" is incorrect, and "Number of live rows fetched by index scans in
>>> this database" is correct?
>>
>> Yes, I think so!
>
> Thanks!
> I updated the patch for summarizing this thread.

Thanks for updating the patch! LGTM.

This is an improvement of documentation, so this should be applied in
v15 dev cycle? If so, could you add the patch to the next CF? Or you think
this is a bug fix and needs to be back-patched?

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION