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If we hit out-of-memory between creating the PGconn and inserting it into dblink's hashtable, we'd lose track of the PGconn, which is quite bad since it represents a live connection to a remote DB. Fix by rearranging things so that we create the hashtable entry first. Also reduce the number of states we have to deal with by getting rid of the separately-allocated remoteConn object, instead allocating it in-line in the hashtable entries. (That incidentally removes a session-lifespan memory leak observed in the regression tests.) There is an apparently-irreducible remaining OOM hazard, which is that if the connection fails at the libpq level (ie it's CONNECTION_BAD) then we have to pstrdup the PGconn's error message before we can release it, and theoretically that could fail. However, in such cases we're only leaking memory not a live remote connection, so I'm not convinced that it's worth sweating over. This is a pretty low-probability failure mode of course, but losing a live connection seems bad enough to justify back-patching. Author: Tom Lane <tgl@sss.pgh.pa.us> Reviewed-by: Matheus Alcantara <matheusssilv97@gmail.com> Discussion: https://postgr.es/m/1346940.1748381911@sss.pgh.pa.us Backpatch-through: 13
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.