From PostgreSQL wiki
Items needed to be discussed.
Features and products SQL/MED should consider about
Itagaki's current work is focused on:
- Integration of contrib/dblink with extensible framework
- ex. memcached-link, oracle-link
- COPY FROM supports directly read external data from FDW
- ex. COPY FROM SERVER remote_postgres
Are there any related features and products that can work with SQL/MED? Meterialized views? GDQ's insert only queues?
What is the best design to support Access Methods for Tables?
Postgres has AMs for indexes, and SQL/MED foreign tables are conterparts for tables.
Itagaki's WIP codes usses an C structure (set of function pointers) for it.
How does we pass WHERE-conditions to FDW routines?
We cannot pass WHERE-condictions to SRF, like dblink() - we need to push down the conditions into the query string. Foreign tables should handle the conditions directly to allow users to write quieris transparently.
Itagaki's WIP codes uses internal expression trees directory. It allows user codes to accuss fully-features, but is complex, requres C codes, and needs to export internal(?) codes for expressions.
FDW vs. SRF
They have overlapped functionalities. Should we need to merge them? For example, FDW routines could be implemented with SRF with meta functions (WHERE-clause handler is one of the meta funcs)
One of the problems in SRF is that result sets are materialized in tuplestores. Foreign tables could return a large number of tuples, so streaming-based protocol is better.