| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Why do we keep UnusedLock1 in LWLockId? |
| Date: | 2009-03-03 07:58:40 |
| Message-ID: | 49ACE330.9050004@enterprisedb.com |
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| Lists: | pgsql-hackers |
ITAGAKI Takahiro wrote:
> There is UnusedLock1 in LWLockId enumerations in storage/lwlock.h .
> | UnusedLock1, /* FreeSpaceMapLock used to be here */
>
> I thought it is for keeping LWLockId same as 8.3 at first,
> but we've already split SInvalLock to SInvalReadLock and
> SInvalWriteLock. So the IDs are changed anyway.
The idea was indeed to keep the lock numbering unchanged. Zdenek
suggested that to make dtrace scripts etc. compatible across versions.
You're right, we split SInvalLock in 8.4, so reserving the slot for
FreeSpaceLock doesn't keep the numbers unchanged. In fact, removing that
will make the rest of the lock numbers the same as in 8.3 again.
I'll remove that.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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