Commit b663a41363 introduced bulk inserts for FDW, but the handling of tuple slots turned out to be problematic for two reasons. Firstly, the slots were re-created for each individual batch. Secondly, all slots referenced the same tuple descriptor - with reasonably small batches this is not an issue, but with large batches this triggers O(N^2) behavior in the resource owner code. These two issues work against each other - to reduce the number of times a slot has to be created/dropped, larger batches are needed. However, the larger the batch, the more expensive the resource owner gets. For practical batch sizes (100 - 1000) this would not be a big problem, as the benefits (latency savings) greatly exceed the resource owner costs. But for extremely large batches it might be much worse, possibly even losing with non-batching mode. Fixed by initializing tuple slots only once (and reusing them across batches) and by using a new tuple descriptor copy for each slot. Discussion: https://postgr.es/m/ebbbcc7d-4286-8c28-0272-61b4753af761%40enterprisedb.com
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.
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Mirror of the official PostgreSQL GIT repository. Note that this is just a *mirror* - we don't work with pull requests on github. To contribute, please see https://wiki.postgresql.org/wiki/Submitting_a_Patch
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