On 9/4/20 6:23 PM, Ashutosh Bapat wrote:
On Thu, 3 Sep 2020 at 10:44, Andrey V. Lepikhov
<a.lepik...@postgrespro.ru <mailto:a.lepik...@postgrespro.ru>> wrote:
On 8/31/20 6:19 PM, Ashutosh Bapat wrote:
> On Mon, Aug 31, 2020 at 3:36 PM Andrey V. Lepikhov
> <a.lepik...@postgrespro.ru <mailto:a.lepik...@postgrespro.ru>> wrote:
>>
>> Thanks for this helpful feedback.
> I think the patch has some other problems like it works only for
> regular tables on foreign server but a foreign table can be pointing
> to any relation like a materialized view, partitioned table or a
> foreign table on the foreign server all of which have statistics
> associated with them. I didn't look closely but it does not consider
> that the foreign table may not have all the columns from the relation
> on the foreign server or may have different names. But I think those
> problems are kind of secondary. We have to agree on the design first.
>
In accordance with discussion i made some changes in the patch:
1. The extract statistic routine moved into the core.
Bulk of the patch implements the statistics conversion to and fro json
format. I am still not sure whether we need all of that code here.
Yes, i'm sure we'll replace it with something.
Right now, i want to discuss format of statistics dump. Remind, that a
statistics dump is needed not only for fdw, but it need for the pg_dump.
And in the dump will be placed something like this:
'SELECT store_relation_statistics(rel, serialized_stat)'
my reasons for using JSON:
* it have conversion infrastructure like json_build_object()
* this is flexible readable format, that can be useful in text dumps of
relations.
Can we re-use pg_stats view? That is converting some of the OIDs to names. I
agree with anyarray but if that's a problem here it's also a problem for
pg_stats view, isn't it?
Right now, I don't know if it is possible to unambiguously convert the
pg_stats information to a pg_statistic tuple.
If we can reduce the stats handling code to a
minimum or use it for some other purpose as well e.g. pg_stats
enhancement, the code changes required will be far less compared to the
value that this patch provides.
+1
--
regards,
Andrey Lepikhov
Postgres Professional
