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Add missing infrastructure for this node type, notably in ruleutils.c where its lack could demonstrably cause EXPLAIN to fail. Add outfuncs/readfuncs support. (outfuncs support is useful today for debugging purposes. The readfuncs support may never be needed, since at present it would only matter for parallel query and NextValueExpr should never appear in a parallelizable query; but it seems like a bad idea to have a primnode type that isn't fully supported here.) Teach planner infrastructure that NextValueExpr is a volatile, parallel-unsafe, non-leaky expression node with cost cpu_operator_cost. Given its limited scope of usage, there *might* be no live bug today from the lack of that knowledge, but it's certainly going to bite us on the rear someday. Teach pg_stat_statements about the new node type, too. While at it, also teach cost_qual_eval() that MinMaxExpr, SQLValueFunction, XmlExpr, and CoerceToDomain should be charged as cpu_operator_cost. Failing to do this for SQLValueFunction was an oversight in my commit 0bb51aa96. The others are longer-standing oversights, but no time like the present to fix them. (In principle, CoerceToDomain could have cost much higher than this, but it doesn't presently seem worth trying to examine the domain's constraints here.) Modify execExprInterp.c to execute NextValueExpr as an out-of-line function; it seems quite unlikely to me that it's worth insisting that it be inlined in all expression eval methods. Besides, providing the out-of-line function doesn't stop anyone from inlining if they want to. Adjust some places where NextValueExpr support had been inserted with the aid of a dartboard rather than keeping it in the same order as elsewhere. Discussion: https://postgr.es/m/23862.1499981661@sss.pgh.pa.us
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.