Cui Shijun wrote:
As the insertion algorithm described, a specific partition lock manage some
items, but these items can be stored in anywhere of the hash table,not
necessarily in a bucket chain.
So there are some problems with "different partitions use different hash
chains",
a partition can use
2007/4/28, Heikki Linnakangas <[EMAIL PROTECTED]>:
3. Lock that partition
6. Unlock partition
I suddenly realize that LW locks are used to manage the lock hash table.So
when a item is to be inserted into hash table, we must gain that partition
lock
first to change that table.
As the insertion
Insertion algorithm in a nutshell:
1. Calculate hash value
2. Take 4 least-significant bits of the hash value. These tell you which
partition the value belongs to.
3. Lock that partition
4. Take the X (X > 4) least significant bits of the hash value. These
tell you which hash bucket the value
Ah... It seems that a item is calculated its hash value, get the bucket
number from it and insert into that bucket "chain". The insertion has
nothing to do with partition number(but Alvaro says "which hash is
used depends on the partition number". I haven't really understood
this: how can we get a
"rancpine cui" <[EMAIL PROTECTED]> writes:
> So the method of calculating the bucket number can promise
> that all items in the bucket link list belong to ONE partition?
It's not that hard: the bucket number is some number of low-order bits
of the hash value, and the partition number is some small
2007/4/27, Alvaro Herrera <[EMAIL PROTECTED]>:
Which hash is used depends on the partition number.
So the method of calculating the bucket number can promise
that all items in the bucket link list belong to ONE partition?
Alvaro Herrera <[EMAIL PROTECTED]> writes:
> rancpine cui escribió:
>> What does "hash chains" mean?
> Each "hash chain" is a different, separate, independent hash struct.
It's pretty much equivalent to "hash bucket" --- this comment says chain
because it's focusing on the physical representation
rancpine cui escribió:
> I've seen from the README that
> "The shared-memory hash tables for LOCKs and PROCLOCKs are organized
> so that different partitions use different hash chains, and thus there
> is no conflict in working with objects in different partitions."
> What does "hash chains" mea
-- Forwarded message --
From: rancpine cui <[EMAIL PROTECTED]>
Date: 2007-4-27 下午9:22
Subject: Re: [HACKERS] How does the partitioned lock manager works?
To: Heikki Linnakangas <[EMAIL PROTECTED]>
Thanks for your reply. :-)
I've seen from the README that
"
rancpine cui wrote:
When the lock manager's data structures were split into "partitions",
how many such data structures can one partition control?
The number of partitions is 16 (NUM_LOCK_PARTITIONS). The total size of
the lock hash table is max_locks_per_xact * (max_connections +
max_pre
Hi,
When the lock manager's data structures were split into "partitions",
how many such data structures can one partition control? Since we use
LOCKTAG's hash value to decide the partition which the lock should in, can
all locks be split into ONE partition?
Regards,
ranc.
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