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Update lock manager README.

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Bruce Momjian 1998-07-06 18:16:07 +00:00
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1 changed files with 7 additions and 19 deletions
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src/backend/storage/lmgr/README
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@ -1,17 +1,12 @@
$Header: /cvsroot/pgsql/src/backend/storage/lmgr/README,v 1.2 1998/01/28 02:29:26 momjian Exp $ $Header: /cvsroot/pgsql/src/backend/storage/lmgr/README,v 1.3 1998/07/06 18:16:07 momjian Exp $
This file is an attempt to save me (and future code maintainers) some There are two fundemental lock structures. Lock methods describe the
time and a lot of headaches. The existing lock manager code at the time locking behavior. We currently only support multi-level locking. Lock
of this writing (June 16 1992) can best be described as confusing. The modes describe the mode of the lock(read/write or shared/exclusive).
complexity seems inherent in lock manager functionality, but variable See src/tools/backend/index.html and src/include/storage/lock.h for more
names chosen in the current implementation really confuse me everytime details.
I have to track down a bug. Also, what gets done where and by whom isn't
always clear....
Starting with the data structures the lock manager relies upon... ---------------------------------------------------------------------------
(NOTE - these will undoubtedly change over time and it is likely
that this file won't always be updated along with the structs.)
The lock manager's LOCK: The lock manager's LOCK:
@ -90,10 +85,3 @@ activeHolders -
--------------------------------------------------------------------------- ---------------------------------------------------------------------------
Locks are accessed in two ways. Each PROC structure has a lockQueue,
that is a circular linked list of LOCK pointers that this process holds
or is waiting on.
Second, there is a hash table that can do a lookup by combined LOCK
address and transaction id(xid) which allows a process to see what
type of locks it holds on that table.