Commit 866e24d47d added an assert that HEAP_XMAX_LOCK_ONLY and
HEAP_KEYS_UPDATED cannot appear together, on the faulty assumption that
the latter necessarily referred to an update and not a tuple lock; but
that's wrong, because SELECT FOR UPDATE can use precisely that
combination, as evidenced by the amcheck test case added here.
Remove the Assert(), and also patch amcheck's verify_heapam.c to not
complain if the combination is found. Also, out of overabundance of
caution, update (across all branches) README.tuplock to be more explicit
about this.
Author: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Mahendra Singh Thalor <mahi6run@gmail.com>
Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com>
Discussion: https://postgr.es/m/20210124061758.GA11756@nol
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.