On 6/28/20 8:10 PM, Tomas Vondra wrote:
Now, the primary reason why the performance degrades like this is that while FDW has batching for SELECT queries (i.e. we read larger chunks of data from the cursors), we don't have that for INSERTs (or other DML). Every time you insert a row, it has to go all the way down into the partition synchronously.
You added new fields into the PgFdwModifyState struct. Why you didn't reused ResultRelInfo::ri_CopyMultiInsertBuffer field and CopyMultiInsertBuffer machinery as storage for incoming tuples?
-- regards, Andrey Lepikhov Postgres Professional
