Horton

Re: Unused header file inclusion

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: vignesh C <vignesh21@gmail.com>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-07-31T15:23:22Z
Lists: pgsql-hackers 
On 2019-Jul-31, vignesh C wrote:

> I noticed that there are many header files being
> included which need not be included.

Yeah, we have tooling for this already in src/tools/pginclude.  It's
been used before, and it has wreaked considerable havoc; see "git log
--grep pgrminclude".

I think doing this sort of cleanup is useful to a point -- as Andres
mentions, some includes are somewhat more "important" than others, so
judgement is needed in each case.

I think removing unnecessary include lines from header files is much
more useful than from .c files.  However, nowadays even I am not very
convinced that that is a very fruitful use of time, since many/most
developers use ccache which will reduce the compile times anyway in many
cases; and development machines are typically much faster than ten years
ago.

Also, I think addition of new include lines to existing .c files should
be a point worth specific attention in patch review, to avoid breaking
reasonable modularity boundaries unnecessarily.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Add fmgr.h include to selfuncs.h.

  2. Add "headerscheck" script to test header-file compilability under C.

  3. Fix failure-to-compile-standalone in scripts_parallel.h.

  4. Remove fmgr.h includes from headers that don't really need it.

  5. Don't include utils/array.h from acl.h.

  6. Remove redundant prototypes for SQL callable functions.

  7. Remove unnecessary #include <limits.h>

  8. Teach tuplesort.c about "top N" sorting, in which only the first N tuples