From: | ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> |
---|---|
To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: rmgr hooks and contrib/rmgr_hook |
Date: | 2008-09-02 09:30:16 |
Message-ID: | 20080902174613.76B2.52131E4D@oss.ntt.co.jp |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers pgsql-patches |
Simon Riggs <simon(at)2ndQuadrant(dot)com> wrote:
> > Why do we need to set rmgr_hook in _PG_init(), and add or mofify rmgrs
> > in our hook functions?
>
> If we modify RmgrTable in _PG_init() then we would have to have that
> structure available in all backends, which was a stated objective to
> avoid. We would still need a fast access data structure for the
> XLogInsert() check, so the RmgrTable would just be wasted space in all
> normal backends. In the patch, plugin is only called when we call
> RmgrInitialize(), so the memory is malloc'd only when required.
Um? AFAICS RmgrTable is not accessed in XLogInsert unless we use WAL_DEBUG.
I see that RmgrTable should be malloc'd when required,
but there is another issue; when to load rmgr libraries.
Rmgr objects are needed only in startup process during recovery.
If we want to reduce resource consumption by rmgrs, I think it is
better not to load rmgr libraries through shared_preload_libraries.
We don't have to load rmgr libs if recovery is not needed or after recovery.
How about adding a new variable "recovery_preload_libaries" like as
shared_preload_libraries? Rmgr libs in it are loaded only in startup
process and only if recovery is needed.
Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center
From | Date | Subject | |
---|---|---|---|
Next Message | Pavel Stehule | 2008-09-02 09:35:48 | Re: statement_cost_limit for regression testing. |
Previous Message | Ryan Bradetich | 2008-09-02 08:52:06 | Re: statement_cost_limit for regression testing. |
From | Date | Subject | |
---|---|---|---|
Next Message | Simon Riggs | 2008-09-02 09:41:27 | Re: WIP Join Removal |
Previous Message | Simon Riggs | 2008-09-02 08:44:24 | Re: rmgr hooks and contrib/rmgr_hook |