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dfd8e6c73e
GIN and GiST indexes utilizing pg_trgm's opclasses store sorted trigrams within index tuples. When comparing and sorting each trigram, pg_trgm treats each character as a 'char[3]' type in C. However, the char type in C can be interpreted as either signed char or unsigned char, depending on the platform, if the signedness is not explicitly specified. Consequently, during replication between different CPU architectures, there was an issue where index scans on standby servers could not locate matching index tuples due to the differing treatment of character signedness. This change introduces comparison functions for trgm that explicitly handle signed char and unsigned char. The appropriate comparison function will be dynamically selected based on the character signedness stored in the control file. Therefore, upgraded clusters can utilize the indexes without rebuilding, provided the cluster upgrade occurs on platforms with the same character signedness as the original cluster initialization. The default char signedness information was introduced in 44fe30fdab6, so no backpatch. Reviewed-by: Noah Misch <noah@leadboat.com> Discussion: https://postgr.es/m/CB11ADBC-0C3F-4FE0-A678-666EE80CBB07%40amazon.com
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.