Hello. While reading the docs for the enable_partitionwise_aggregate parameter on the Query Planning page, I thought the description had a small mistake that could be improved.
The current wording is: "which allows grouping or aggregation on a partitioned tables performed separately "
(Option 1) a "partitioned table's partitions" (the possessive form of "it's"). The "enable_partition_pruning" parameter uses "the partitioned table's partitions" in this form. I think this option is good, but I had a slight preference for option 2.
(Option 2) Or to just cut out the first part and say "to be performed separately for each partition", which seemed simpler. So the sentence reads: "which allows grouping or aggregation to be performed separately for each partition"
(Option 3) dropping the "a" so it says "which allows grouping or aggregation on partitioned tables performed separately". I don't think this is as good though because the aggregation happens on the partitions, so it feels slightly off to me to say the "partitioned tables" instead of the partitions.
I tested toggling this parameter on and off with a test partitioned table, and looked at the query execution plan, and saw how the aggregation happened on the partitions first when it was enabled.
This is my first ever submission to pgsql-hackers. :) I used this guide from Lætitia to prepare the patch file for Option 2 above, which is attached. I am having a problem with the "make STYLE=website html" step, so I hadn't seen the preview (still fixing this up). https://mydbanotebook.org/post/patching-doc/
