sgmr* vs. md*

On Sun, 16 May 1999, Bruce Momjian wrote:

I just changed the call from mdunlink to smgrunlink, but this brings up
a good point.

Thanks, I should have noticed that myself...

smgr is a generic i/o interface layer that allows multiple storage
managers. Currently, we always use DEFAULT_SMGR as a parameter to smgr*
functions, causing calls to the md* routines. Is there any value in
just removing the smgr layer completely. It was originally for a CD
jutebox i/o layer in addition to our current disk i/o layer.

I think that extra layer is a very good idea. Some new kind of storage
might come along that someone wants to use, and md.c wouldn't do the right
thing.

Since it's such a thin layer, performance doesn't really suffer. Doesn't
hurt to keep it...

Ole Gjerde

smgr is a generic i/o interface layer that allows multiple storage
managers. Currently, we always use DEFAULT_SMGR as a parameter to smgr*
functions, causing calls to the md* routines. Is there any value in
just removing the smgr layer completely. It was originally for a CD
jutebox i/o layer in addition to our current disk i/o layer.

Wouldn't this be the interface for a tablespace i/o manager ?
A tablespace has the advatage of only needing a number of files
for thousands of small tables, and reduces the overhead of many
open file handles. A tablespace is also needed before raw devices
can be efficiently exploited.

Andreas

smgr is a generic i/o interface layer that allows multiple storage
managers. Currently, we always use DEFAULT_SMGR as a parameter to smgr*
functions, causing calls to the md* routines. Is there any value in
just removing the smgr layer completely. It was originally for a CD
jutebox i/o layer in addition to our current disk i/o layer.

Wouldn't this be the interface for a tablespace i/o manager ?
A tablespace has the advatage of only needing a number of files
for thousands of small tables, and reduces the overhead of many
open file handles. A tablespace is also needed before raw devices
can be efficiently exploited.

Good point.

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