>> This seems to be related to re-using the table-name between invocations. The >> attached patch should fix point 2. As for point 1, I don't know the cause for >> it. Do you have a reproducible test case ? > Sure. I'll try harder when looking in more details at the patch for > postgres_fdw :)
With v2, I have tried randomly some of the scenarios of v1 plus some extras, but was not able to reproduce it.
> I'll look into the patch for postgres_fdw later.
And here are some comments about it, when applied on top of the other 2 patches. 1) Code compiles without warning, regression tests pass. 2) In fetch_remote_tables, the palloc for the parameters should be done after the number of parameters is determined. In the case of IMPORT_ALL, some memory is wasted for nothing. 3) Current code is not able to import default expressions for a table. A little bit of processing with pg_get_expr would be necessary: select pg_catalog.pg_get_expr(adbin, adrelid) from pg_attrdef; There are of course bonus cases like SERIAL columns coming immediately to my mind but it would be possible to determine if a given column is serial with pg_get_serial_sequence. This would be a good addition for the FDW IMO. 4) The same applies of course to the constraint name: CREATE FOREIGN TABLE foobar (a int CONSTRAINT toto NOT NULL) for example. 5) A bonus idea: enable default expression obtention and null/not null switch by default but add options to disable their respective obtention. 6) Defining once PGFDW_IMPORTRESULT_NUMCOLS at the top of postgres_fdw.c without undefining would be perfectly fine. 7) In postgresImportForeignSchema, the palloc calls and the definitions of the variables used to save the results should be done within the for loop. 8) At quick glance, the logic of postgresImportForeignSchema looks awkward... I'll have a second look with a fresher mind later on this one.
While having a second look at the core patch, I have found myself re-hacking it, fixing a couple of bugs and adding things that have been missing in the former implementation:
- Deletions of unnecessary structures to simplify code and make it cleaner
- Fixed a bug related to the management of local schema name. A FDW was free to set the schema name where local tables are created, this should not be the case.
- Improved documentation, examples and other things, fixed doc padding for example
- Added some missing stuff in equalfuncs.c and copyfuncs.c
- Some other things.
With that, core patch looks pretty nice actually, and I think that we should let a committer have a look at this part at least for this CF.
Also, the postgres_fdw portion has been updated based on the previous core patch modified, using a version that Ronan sent me, which has addressed the remarks I sent before. This patch is still lacking documentation, some cleanup, and regression tests are broken, but it can be used to test the core feature. I unfortunately don't have much time today but I am sending this patch either way to let people play with IMPORT SCHEMA if I don't come back to it before.
