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After taking awhile to digest the row-processor feature that was added to libpq in commit 92785dac2ee7026948962cd61c4cd84a2d052772, we've concluded it is over-complicated and too hard to use. Leave the core infrastructure changes in place (that is, there's still a row processor function inside libpq), but remove the exposed API pieces, and instead provide a "single row" mode switch that causes PQgetResult to return one row at a time in separate PGresult objects. This approach incurs more overhead than proper use of a row processor callback would, since construction of a PGresult per row adds extra cycles. However, it is far easier to use and harder to break. The single-row mode still affords applications the primary benefit that the row processor API was meant to provide, namely not having to accumulate large result sets in memory before processing them. Preliminary testing suggests that we can probably buy back most of the extra cycles by micro-optimizing construction of the extra results, but that task will be left for another day. Marko Kreen
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 "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.