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  3970 
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.u ni-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.u ni-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.e ye-bee-em.com> wrote in message news:<ow******* **************@ twister01.bloor .is.net.cable.r ogers.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 concerns was frequent calls to new and delete, which can
cause
memory fragmentation over time. An example is the allocation and
destruction
|
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 database manager needs them.
But in that case, the BP hit ratio will be 0% (BP physical reads = BP async.
physical reads = BP logical reads).
Could...
|
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 & prodb & MYNODEB has an alias database dbload - catalog
from proda initially. Three end-users are currently connected to dbload.
NODE MYNODEA:...
|
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 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...
|
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 of 2 hours, but
property setting for the relevant App Pool is 1 hour (and there is no
activity following the placement of the data into the...
| | |
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. I think learning
PostgreSQL will not be as difficult as I thought it would be. I've also
been googling for the last few days, but I have a...
|
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
that they are virtually identical except that db2_mmap_read/write
applies at an instance level and concurrent i/o can be aplied at a
tablespace level....
|
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 memory.
The
buffer pool ratio should be close to 100%. It's about 80% at the
moment.
Would a "select all" statement cache everything in the...
|
by: Hystou |
last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it.
First, let's disable language...
|
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, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed.
This is as boiled down as I can make it. ...
| | |
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 protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the...
|
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, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then...
|
by: conductexam |
last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one.
At the time of converting from word file to html my equations which are in the word document file was convert...
|
by: TSSRALBI |
last post by:
Hello
I'm a network technician in training and I need your help.
I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs.
The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols.
I succeeded, with both firewalls in...
|
by: adsilva |
last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
|
by: muto222 |
last post by:
How can i add a mobile payment intergratation into php mysql website.
| | |
by: bsmnconsultancy |
last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating...
| |
