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c941aed96b
The original coding in contrib/uuid-ossp created and destroyed a uuid_t object (or, in some cases, even two of them) each time it was called. This is not the intended usage: you're supposed to keep the uuid_t object around so that the library can cache its state across uses. (Other UUID libraries seem to keep equivalent state behind-the-scenes in static variables, but OSSP chose differently.) Aside from being quite inefficient, creating a new uuid_t loses knowledge of the previously generated UUID, which in theory could result in duplicate V1-style UUIDs being created on sufficiently fast machines. On at least some platforms, creating a new uuid_t also draws some entropy from /dev/urandom, leaving less for the rest of the system. This seems sufficiently unpleasant to justify back-patching this change.
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.