Re: Import Statistics in postgres_fdw before resorting to sampling.
| От | Corey Huinker |
|---|---|
| Тема | Re: Import Statistics in postgres_fdw before resorting to sampling. |
| Дата | |
| Msg-id | CADkLM=exH-6QAZE9sLBGH=GPkfUUC=dXp6VvYfRkEfJfuKwPNA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Import Statistics in postgres_fdw before resorting to sampling. ("Matheus Alcantara" <matheusssilv97@gmail.com>) |
| Ответы |
Re: Import Statistics in postgres_fdw before resorting to sampling.
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| Список | pgsql-hackers |
+
I don't think that it's good to make StatisticsAreImportable() routine
check if fetch_stats is enabled on foreign server/table options because
if so, every fdw implementation would need this same block of code and
also fdw implementations may forget or bypass these options which I
don't think that it would be a desired behavior. What about move this
check to analyze_rel()? Perhaps create a function that just check if the
fetch_stats is enabled.
StatisticsAreImportable() is a virtual function whose goal is to determine if this specific table supports stats exporting.
postgresStatisticsAreImportable() is the postgres_fdw implementation of that virtual function.
Any other FDWs that want to implement stats import will need to invent their own tests and configurations to determine if that is possible.
If the above statement make sense, it seems to me that
StatisticsAreImportable() may not be needed at all.
It wasn't there, initially.
I think that we could make analyze_rel() check if fetch_stats is enable
on the foreign server/table and then call ImportStatistics() which could
return true or false.
That we can't do, because there's a chance that those FDWs already have a setting named fetch_stats.
If it returns true it means that the statistics
was imported successfully, otherwise if it returns false we could
fallback to table sampling as we already do today. ImportStatistics
could return false if the foreign server don't have statistics for the
requested table, even after running ANALYZE if remote_analyze is true.
Is that make sense? Any thoughts?
That sounds very similar to the design that was presented in v1.
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