Re: Streaming I/O, vectored I/O (WIP)

On Tue, Apr 2, 2024 at 9:39 PM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> So this is the version I'm going to commit shortly, barring objections.

And done, after fixing a small snafu with smgr-only reads coming from
CreateAndCopyRelationData() (BM_PERMANENT would be
incorrectly/unnecessarily set for unlogged tables).

Here are the remaining patches discussed in this thread. They give
tablespace-specific io_combine_limit, effective_io_readahead_window
(is this useful?), and up-to-1MB io_combine_limit (is this useful?).
I think the first two would probably require teaching reloption.c how
to use guc.c's parse_int() and unit flags, but I won't have time to
look at that for this release so I'll just leave these here.

On the subject of guc.c, this is a terrible error message... did I do
something wrong?

postgres=# set io_combine_limit = '42MB';
ERROR: 5376 8kB is outside the valid range for parameter
"io_combine_limit" (1 .. 32)