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6bc1fd4e60
Some of the ambuildempty functions used smgrwrite() directly, followed by smgrimmedsync(). A few small problems with that: Firstly, one is supposed to use smgrextend() when extending a relation, not smgrwrite(). It doesn't make much difference in production builds. smgrextend() updates the relation size cache, so you miss that, but that's harmless because we never use the cached relation size of an init fork. But if you compile with CHECK_WRITE_VS_EXTEND, you get an assertion failure. Secondly, the smgrwrite() calls were performed before WAL-logging, so the page image written to disk had 0/0 as the LSN, not the LSN of the WAL record. That's also harmless in practice, but seems sloppy. Thirdly, it's better to use the buffer cache, because then you don't need to smgrimmedsync() the relation to disk, which adds latency. Bypassing the cache makes sense for bulk operations like index creation, but not when you're just initializing an empty index. Creation of unlogged tables is hardly performance bottleneck in any real world applications, but nevertheless. Backpatch to v16, but no further. These issues should be harmless in practice, so better to not rock the boat in older branches. Reviewed-by: Robert Haas Discussion: https://www.postgresql.org/message-id/6e5bbc08-cdfc-b2b3-9e23-1a914b9850a9@iki.fi
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.