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da7d44b627
Previously, querying the xmin column of a single postgres_fdw foreign table fetched the tuple length, xmax the typmod, and cmin or cmax the composite type OID of the tuple. However, when you queried several such tables and the join got shipped to the remote side, these columns ended up containing the remote values of the corresponding columns. Both behaviors are rather unprincipled, the former for obvious reasons and the latter because the remote values of these columns don't have any local significance; our transaction IDs are in a different space than those of the remote machine. Clean this up by setting all of these fields to 0 in both cases. Also fix the handling of tableoid to be sane. Robert Haas and Ashutosh Bapat, reviewed by Etsuro Fujita.
The PostgreSQL contrib tree
---------------------------
This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree. This does not preclude their
usefulness.
User documentation for each module appears in the main SGML
documentation.
When building from the source distribution, these modules are not
built automatically, unless you build the "world" target. You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.
Some directories supply new user-defined functions, operators, or
types. To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command. In a fresh database,
you can simply do
CREATE EXTENSION module_name;
See the PostgreSQL documentation for more information about this
procedure.