The PostgreSQL contrib tree
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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 "gmake all" and "gmake
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.
Tom Lane
authored
The previous coding supposed that the first differing bytes in two varlena datums must have the same sign difference as their overall comparison result. This is obviously bogus for text strings in non-C locales, and probably wrong for numeric, and even for bytea I think it was wrong on machines where char is signed. When the assumption failed, the function could deliver a zero or negative penalty in situations where such a result is quite ridiculous, leading the core GiST code to make very bad page-split decisions. To fix, take the absolute values of the byte-level differences. Also, switch the code to using unsigned char not just char, so that the behavior will be consistent whether char is signed or not. Per investigation of a trouble report from Tomas Vondra. Back-patch to all supported branches.