I understand the concept of catalog cache (memory allocated from the
dbheap to allow catalog lookups without the need to access disk each
time). But the DB2 catalog tablespace (SYSCATSPACE) is assigned a
buffer pool, which seems to perform the same function as catalog
cache.
Is this simply a case of double buffering? Can anyone clear this up?
6  3954 
Mark wrote: I understand the concept of catalog cache (memory allocated from the
dbheap to allow catalog lookups without the need to access disk each
time). But the DB2 catalog tablespace (SYSCATSPACE) is assigned a
buffer pool, which seems to perform the same function as catalog
cache.
Is this simply a case of double buffering? Can anyone clear this up?
One thing the catalog cache does but the buffer pool (BP) does not is the
caching of the packed descriptors for various kinds of objects. The packed
descriptors are modeled as BLOBs, and BLOBs don't go through the buffer
pool.
--
Knut Stolze
Information Integration
IBM Germany / University of Jena
Knut Stolze <st****@de.ibm.com> wrote in message news:<cf**********@fsuj29.rz.uni-jena.de>...
One thing the catalog cache does but the buffer pool (BP) does not is the
caching of the packed descriptors for various kinds of objects. The packed
descriptors are modeled as BLOBs, and BLOBs don't go through the buffer
pool.
But the BLOB's, CLOB's themselves still require direct reads from disk, correct?
No, it's the Blobs that are cached. The cache also includes routine
signatures. So DB2, once the cache, is warm will barely touch the
catalog (including the buffer pool) anymore unless things change.
Cheers
Serge
Mark wrote: Knut Stolze <st****@de.ibm.com> wrote in message
news:<cf**********@fsuj29.rz.uni-jena.de>...
One thing the catalog cache does but the buffer pool (BP) does not is the
caching of the packed descriptors for various kinds of objects. The
packed descriptors are modeled as BLOBs, and BLOBs don't go through the
buffer pool.
But the BLOB's, CLOB's themselves still require direct reads from disk,
correct?
Not if those LOBs are in the catalog cache.
--
Knut Stolze
Information Integration
IBM Germany / University of Jena
Serge Rielau <sr*****@ca.eye-bee-em.com> wrote in message news:<ow*********************@twister01.bloor.is.n et.cable.rogers.com>... No, it's the Blobs that are cached. The cache also includes routine
signatures. So DB2, once the cache, is warm will barely touch the
catalog (including the buffer pool) anymore unless things change.
Cheers
Serge
The BLOB's, CLOB's are cached in the catalog cache, or are they cached
somewhere else? I am talking about user created BLOB's and CLOB's, not
the ones in the Catalog tables.
Mark wrote: The BLOB's, CLOB's are cached in the catalog cache, or are they cached
somewhere else? I am talking about user created BLOB's and CLOB's, not
the ones in the Catalog tables.
Ah, regular CLOBs and LOBs are not cached.
Cheers
Serge This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
by: Tron Thomas |
last post by:
As part of applying for a programming position at a company, I
recently I had submitted some code samples to one of the developers
for review.
This is the feedback I received:
One of his...
|
by: eric |
last post by:
Hi there,
BP hit ratio = 1 - (BP physical reads / BP logical reads).
If all the BP physical reads are asynchronous, it should mean that the pages
are brought up to the bufferpool before the...
|
by: maricel |
last post by:
Could somebody confirm the behavior of UNCATALOG & CATALOG command based on
the following situation:
There are two NODES on DB2 UDB v8.1, MYNODEA & MYNODEB. MYNODEA has two
databases proda &...
|
by: Mark |
last post by:
I understand the concept of catalog cache (memory allocated from the
dbheap to allow catalog lookups without the need to access disk each
time). But the DB2 catalog tablespace (SYSCATSPACE) is...
|
by: Jeremy S. |
last post by:
Just wondering if/how a sliding Cache expiration interacts with Application
Pool Worker Process Recycling.
Specifically, if I were to place some value into the Cache object with a
sliding window...
|
by: Don Kelloway |
last post by:
I'm a first-time user with PostgreSQL so please forgive my ignorance.
I've purchased (and read) Practical PostgreSQL (O'Reilly) and PostgreSQL
Essential Reference (New Riders). So far, so good. ...
|
by: Raj |
last post by:
I created a refresh deferred MQT, and during full refresh there were 4
or 5 lock waits, all waiting on a 'S' lock on Internal Catalog Cache ?
Can some one explain how to prevent this from happening?
|
by: sethwai |
last post by:
Hi,
I've read everything I can get my hands on and am still very
confused about the similarities and differences between
db2_mmap_read/write and concurrent i/o. It seems to me at this point...
|
by: Patrick Finnegan |
last post by:
Is there a DB2 setting that will force a table to be cached in
the
buffer pool? We have four tables that we want to cache completely
in
the buffer pool to ensure that all the data is read from...
|
by: Charles Arthur |
last post by:
How do i turn on java script on a villaon, callus and itel keypad mobile phone
|
by: emmanuelkatto |
last post by:
Hi All, I am Emmanuel katto from Uganda. I want to ask what challenges you've faced while migrating a website to cloud.
Please let me know.
Thanks!
Emmanuel
|
by: BarryA |
last post by:
What are the essential steps and strategies outlined in the Data Structures and Algorithms (DSA) roadmap for aspiring data scientists? How can individuals effectively utilize this roadmap to progress...
|
by: Sonnysonu |
last post by:
This is the data of csv file
1 2 3
1 2 3
1 2 3
1 2 3
2 3
2 3
3
the lengths should be different i have to store the data by column-wise with in the specific length.
suppose the i have to...
|
by: marktang |
last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However,...
|
by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers,...
|
by: jinu1996 |
last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven...
|
by: tracyyun |
last post by:
Dear forum friends,
With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each...
|
by: agi2029 |
last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing,...
| |
