mirror of
https://github.com/postgres/postgres.git
synced 2025-11-10 17:42:29 +03:00
31338352bd
* removed a few redundant defines
* get_user_name safe under win32
* rationalized pipe read EOF for win32 (UPDATED PATCH USED)
* changed all backend instances of sleep() to pg_usleep
- except for the SLEEP_ON_ASSERT in assert.c, as it would exceed a
32-bit long [Note to patcher: If a SLEEP_ON_ASSERT of 2000 seconds is
acceptable, please replace with pg_usleep(2000000000L)]
I added a comment to that part of the code:
/*
* It would be nice to use pg_usleep() here, but only does 2000 sec
* or 33 minutes, which seems too short.
*/
sleep(1000000);
Claudio Natoli
# $PostgreSQL: pgsql/src/backend/storage/smgr/README,v 1.3 2004/02/10 01:55:26 tgl Exp $
In the original Berkeley Postgres system, there were several storage managers,
of which only the "magnetic disk" manager remains. (At Berkeley there were
also managers for the Sony WORM optical disk jukebox and persistent main
memory, but these were never supported in any externally released Postgres,
nor in any version of PostgreSQL.) However, we retain the notion of a storage
manager switch in case anyone wants to reintroduce other kinds of storage
managers.
In Berkeley Postgres each relation was tagged with the ID of the storage
manager to use for it. This is gone. It would be more reasonable to
associate storage managers with tablespaces (a feature not present as this
text is being written, but one likely to emerge soon).
The files in this directory, and their contents, are
smgrtype.c Storage manager type -- maps string names to storage manager
IDs and provides simple comparison operators. This is the
regproc support for type 'smgr' in the system catalogs.
(This is vestigial since no columns of type smgr exist
in the catalogs anymore.)
smgr.c The storage manager switch dispatch code. The routines in
this file call the appropriate storage manager to do hardware
accesses requested by the backend. smgr.c also manages the
file handle cache (SMgrRelation table).
md.c The magnetic disk storage manager.
Note that md.c in turn relies on src/backend/storage/file/fd.c.