Cache usage

Our application has a table that is repeatedly queried; the queries may contain predicates involving non-primary key columns. Ideally, we would want to cache this entire table in memory to speed up retrieval. We are checking to see if TopLink's cache can do the needful for us.
From browsing the documentation and the forum, it appears that TopLink displays the following behaviour -
1. By default, the database is bypassed and the cache is used only when queries contain primary-key predicates.
2. Direct usage of SQL queries will lead to the cache being bypassed and the database being used; only Expression objects result in the the usage of the cache provided point 1 above is satisfied.
3. The CheckCacheThenDatabase option has to be configured in order that queries with predicates involving non-primary key columns run against the cache.
Are the points listed above valid? Any suggestions or corrections would be highly appreciated.
Thanks,
CR

These statements are all accurate. By default, only PK queries hit the cache only, all hard coded SQL queries will go to the database and you can configure each query on an individual basis to hit the cache first or go straight to the database.
Note that some advanced queries must always go to the database, i.e., queries with subqueries.
- Don

Similar Messages

High cache usage of free memory

I dont know if this is normal but my fresh archlinux x86_64 install with Xfce uses round 300Mb of 4Gb ram space after boot but then after i start and close some programs i get to 3 Gb used of 3.87 Gb free memory when all applycation are closed. Now i understand that kernel caches some data in memory but i cant clear it all with commands:
sync
echo 1 > /proc/sys/vm/drop_caches
echo 2 > /proc/sys/vm/drop_caches
echo 3 > /proc/sys/vm/drop_caches
After i do that system reports 540 Mb used compared to 300Mb from boot. Is there a way to limit the ammount of cache usage so i dont end up having all free memory used by cache?
Last edited by Anril (2009-12-29 13:19:52)

Ram that is unused is wasted ram, the linux kernel manages it very well so no worries there.
If you have swap usage it's because most probably you have things stored in the ram that are not being used often but cannot be discarded too so things being used more often take precedence.
If you think you have enough ram for all your needs then why not disable swap? I've read that there might be a speed penalty for running without swap but I've been running my system without swap (arch64 4G ram) and I've never had any bad surprises.
There are a few things that might prompt swap usage (don't quote me on that though, it just seems to me to be the case), if you copy many files from one place to the other the kernel will use all the ram available to try to cache them, if you copy many GB then all the ram will get filled (and maybe other things will get evicted to swap).
It's not a bug, free ram is there to be used, things that have been used/needed recently get to stay in the ram, other things can go to the swap, if you can cache a file that has been recently used and need to use it again shortly after then it's much faster if it is in the ram instead of having to read it again from the hard disk. The logic behind it is good, it's just that some corner cases may make behave badly.

Data Cache usage 96%

Hi Experts,
With total 7 planning versions and total size of 9GB, the data cache is constantly filling up
Total 14GB allocated and each time we create a new version the usage goes up by 10%.
There are no old sessions more than 4 hrs and when 5 planners starts working simutaneously, the cache starts filling up
Thanks,
Naren

> With total 7 planning versions and total size of 9GB, the data cache is constantly filling up
>
> Total 14GB allocated and each time we create a new version the usage goes up by 10%.
>
> There are no old sessions more than 4 hrs and when 5 planners starts working simutaneously, the cache starts filling up
Now what?
You create multiple versions of liveCache objects in parallel - of course the cache usage will increase (and also the used space in the data area).
That's how the multi-version-data-handling works.
A copy of the current version is created for each new version.
So either add more cache, reduce your planning version complexity/size or do less in parallel if you want to prevent the cache from beeing used 100%.
regards,
Lars

Livecache data cache usage - table monitor_caches

Hi Team,
We have a requirement of capturing the Data cache usage of Livecache on an hourly basis.
Instead of doing it manually by going into LC10 and copying the data into an excel, is there a table which captures this data on a periodic basis which we can use to get the report at a single shot.
"monitor_caches" is one table which holds this data, but we are not sure how we can get the data from this table. Also, we need to see the contents of this table, we are not sure how we can do that.
As "monitor_caches" is a maxdb table I am not sure how I can the data from this table. I have never worked on Maxdb before.
Has anyone had this requirement.
Warm Regards,
Venu

Hi,
For Cache usage below tables can be referred
Data Cache Usage - total (table MONITOR_CACHES)
Data Cache Usage - OMS Data (table MONITOR_CACHES)
Data Cache Usage - SQL Data (table MONITOR_CACHES)
Data Cache Usage - History/Undo (table MONITOR_CACHES)
Data Cache Usage - OMS History (table MONITOR_CACHES)
Data Cache Usage - OMS Rollback (table MONITOR_CACHES)
Out Of Memory Exceptions (table SYSDBA.MONITOR_OMS)
OMS Terminations (table SYSDBA.MONITOR_OMS)
Heap Usage (table OMS_HEAP_STATISTICS)
Heap Usage in KB (table OMS_HEAP_STATISTICS)
Maximum Heap Usage in KB (table ALLOCATORSTATISTICS)
System Heap in KB (table ALLOCATORSTATISTICS)
Parameter OMS_HEAP_LIMIT (KB) (dbmrfc command param_getvalue OMS_HEAP_LIMIT)
For reporting purpose , look into the following BW extractors and develop BW report.
/SAPAPO/BWEXDSRC APO -> BW: Data Source - Extractor
/SAPAPO/BWEXTRAC APO -> BW: Extractors for Transactional Data
/SAPAPO/BWEXTRFM APO -> BW: Formula to Calculate a Key Figure
/SAPAPO/BWEXTRIN APO -> BW: Dependent Extractors
/SAPAPO/BWEXTRMP APO -> BW: Mapping Extractor Structure Field
Hope this helps.
Regards,
Deepak Kori

Tuning filesystem cache usage to benefit Oracle db workloads

We have several OEL 6 servers running Oracle 11g workloads. Typical output from a "free" command on a system with 8 Gig RAM shows 5 to 6 Gig cache usage.
Are there VMM tuning parameters that can be set to bias the system to use less filesystem cache?
In EL 5 and earlier there was a kernel tunable called vm.pagecache that I believe was used to tune cache behavior, but it is not present in OEL 6.
Thanks

IBM provides excellent documentation.
Unfortunately, to find such information for Linux requires to get bits and pieces from here or there. The available documentation has often too much room for interpretation if you already have a technical background, or is too detailed, making it difficult to comprehend. However, I guess the problem pretty much applies to all products developed during the last decade.
I have honestly no experience with AIX. My experience with commercial Unix systems is limited to Tru64, which is all RIP now. IT is a strange business, often favoring trivial over more superior solutions, eventually coming around in the end. Linux has certainly come a long way. However, it is under constant development and can implement drastic changes, for instance, raw disk support.
By the way, OEL was renamed to Oracle Linux. OL uses the Oracle UEK kernel by default, which is optimized for Oracle products. Product patches and errata can be downloaded for free from Oracle Public Yum. To simplify the initial installation, you can install the "oracle-rdbms-server-11gR2-preinstall" package. It does the setup of kernel parameters, oracle groups and accounts, and triggers the installation of prerequisite software for Oracle DB installation.
For performance reasons, you might want to setup the system to use kernel hugepages, which is apparently the number 1 performance issue related to Oracle under Linux. Hugepages are a significant drop in server resource utilization for memory and processing. The following links should be helpful:
/dev/shm on Oracle Linux 6.x to run Oracle 11g R2 - manual configuration?
Re: Understanding kernel hugepages and Oracle 11g AMM compatibility

Buffer Cache Usage

How can I calculate current buffer cache usage?

Hi;
What is Db version?
Pelase see:
http://blog.lishman.com/2008/05/oracle-quick-tip-querying-buffer-cache.html
Also see below googling which is mention your question's answer
http://www.google.com.tr/#hl=tr&source=hp&q=buffer+cache+usage%3F+&oq=buffer+cache+usage%3F+&aq=f&aqi=&aql=&gs_sm=e&gs_upl=0l0l0l250l0l0l0l0l0l0l0l0ll0&fp=503f556dbe78c402&biw=1280&bih=797
Regard
Helios

Transcation code to monitor the live cache usage

Hi, I wanted to know the transcation to check the live cache & optimser usage ??
Regards,
Bhavesh

Hi Bhavesh,
The following are the transaction codes as required by you.
1) LC10 - Livecache Monitoring
2) /SAPAPO/OM03 - liveCache Test Program: Start liveCache Check
3) /SAPAPO/OM04 - LCA Version
4) /SAPAPO/OM11 - Livecache Log
5) /SAPAPO/OM12 - Delete Livecache Log
6) /SAPAPO/OM13 - Analyze liveCache and LCA Objects
7) /SAPAPO/OM17 - liveCache Consistency Check
8) /SAPAPO/OPT_STOP - Terminate Optimization Runs
9) /SAPAPO/OPT12 - Optimisation Process Overview
10)/SAPAPO/OPT03 - Optimisation User Overview
11)/SAPAPO/OPT11 - Optimisation Log Display
Hope the above information is useful for you. Please confirm
Regards
R. Senthil Mareeswaran.

Disabling cache usage in IE by java(this is really very important and urgen

Hi,
i would like to know if it is possible to disable cache memory(tempinternetfile) for IE.
Since my jsp pages have the meta tag <META HTTP-EQUIV="Pragma" CONTENT="no-cache"> some of the pages are being stored in temporary internet files folder and being called from there and this cause really big problems since all the data has to come from database,
they just came from cache and none of the changes are being displayed.
Thanks

Try add page expire date:
<META HTTP-EQUIV="expires" CONTENT="Fri, 31 Dec 2001 23:59:59 GMT">

Kodo Data Cache Usage

I'm using Kodo 2.3.2 running in a managed environment (JBoss 3.x). I have
it configured to use the "LocalCache" for caching of object instances and I
can see that the cache is working.
Does anyone know how I can get a reference to the DataCache? There is
example code in section 7.3.2 of the Kodo Manual, but that code doesn't
compile for me.
The specific code from the manual is:
PersistenceManagerFactoryImpl factory = (PersistenceManagerFactoryImpl)
pm.getPersistenceManagerFactory();
factory.getDataCache().pin(JDOHelper.getObjectId(o));
The PersistenceManagerFactoryImpl doesn't have a method "getDataCache".
Thanks in advance.

Oops; that should be 'factory.getConfiguration ().getDataCache ()'.
-Fred
In article <amphkp$bes$[email protected]>, TJanusz wrote:
I'm using Kodo 2.3.2 running in a managed environment (JBoss 3.x). I have
it configured to use the "LocalCache" for caching of object instances and I
can see that the cache is working.
Does anyone know how I can get a reference to the DataCache? There is
example code in section 7.3.2 of the Kodo Manual, but that code doesn't
compile for me.
The specific code from the manual is:
PersistenceManagerFactoryImpl factory = (PersistenceManagerFactoryImpl)
pm.getPersistenceManagerFactory();
factory.getDataCache().pin(JDOHelper.getObjectId(o));
The PersistenceManagerFactoryImpl doesn't have a method "getDataCache".
Thanks in advance.
Fred Lucas
SolarMetric Inc.
202-595-2064 x1122
http://www.solarmetric.com

JMX Attributes do not reflect cache usage

I am fairly new to the Coherence product. I was attempting to look at the MBean attributes of the distributed cache that my application uses as is listed by the HttpAdaptor(jmx 8082). All the values(AverageGetMillis/AverageHitMillis....) seem to be '0' . Any clues on what i might be doing wrong.
The Coherence version is 3.1.1/341 and it is using JDK 1.4.2.07 to launce the cache.
Thanks

Here are the config files. I had problems attaching the screen dump, so i have just pasted a few of the attributes:
Thanks
Ramdas
List of MBean attributes:
Name      Type      Access      Value
AverageGetMillis      java.lang.Double      RO      0.0
AverageHitMillis      java.lang.Double      RO      0.0
AverageMissMillis      java.lang.Double      RO      0.0
AveragePutMillis      java.lang.Double      RO      0.0
---------distributed-cache-config.xml----------------------
<?xml version="1.0"?>
<!DOCTYPE cache-config SYSTEM "cache-config.dtd">
<cache-config>
<caching-scheme-mapping>

<cache-mapping>
<cache-name>*</cache-name>
<scheme-name>default-distributed</scheme-name>
</cache-mapping>
<cache-mapping>
<cache-name>miCache</cache-name>
<scheme-name>default-replicated</scheme-name>
</cache-mapping>
</caching-scheme-mapping>
<caching-schemes>

<near-scheme>
<scheme-name>default-near</scheme-name>
<front-scheme>
<local-scheme>
<scheme-ref>default-eviction</scheme-ref>
     <high-units>5000</high-units>
</local-scheme>
</front-scheme>
<back-scheme>
<distributed-scheme>
<scheme-ref>default-distributed</scheme-ref>
</distributed-scheme>
</back-scheme>
<invalidation-strategy>auto</invalidation-strategy>
<autostart>true</autostart>
</near-scheme>

<distributed-scheme>
<scheme-name>default-distributed</scheme-name>
<service-name>DistributedCache</service-name>
<backing-map-scheme>
<class-scheme>
<scheme-ref>default-backing-map</scheme-ref>
</class-scheme>
</backing-map-scheme>
<autostart>true</autostart>
</distributed-scheme>
<replicated-scheme>
<scheme-name>default-replicated</scheme-name>
<service-name>ReplicatedCache</service-name>
<backing-map-scheme>
<class-scheme>
<scheme-ref>default-backing-map</scheme-ref>
</class-scheme>
</backing-map-scheme>
</replicated-scheme>

<class-scheme>
<scheme-name>default-backing-map</scheme-name>
<class-name>com.tangosol.util.SafeHashMap</class-name>
<init-params></init-params>
</class-scheme>

<local-scheme>
<scheme-name>default-eviction</scheme-name>
<eviction-policy>HYBRID</eviction-policy>
<high-units>0</high-units>
<low-units>0</low-units>
<expiry-delay>3600</expiry-delay>
<flush-delay>0</flush-delay>
<cachestore-scheme></cachestore-scheme>
</local-scheme>
</caching-schemes>
</cache-config>
----------------------------------tangosol-coherence-override.xml-----------------------
<coherence>
<cluster-config>
     <authorized-hosts>
          <host-address id="1">dev01</host-address>
          <host-address id="2">dev02</host-address>
     </authorized-hosts>
     <multicast-listener>
          <address system-property="tangosol.coherence.clusteraddress">224.3.10.10</address>
          <port system-property="tangosol.coherence.clusterport">31341</port>
          <time-to-live system-property="tangosol.coherence.ttl">2</time-to-live>
          <join-timeout-milliseconds>30000</join-timeout-milliseconds>
     </multicast-listener>
     <shutdown-listener>
          <enabled system-property="tangosol.coherence.shutdownhook">none</enabled>
     </shutdown-listener>
</cluster-config>
<logging-config>
<destination system-property="tangosol.coherence.log">stderr</destination>
<severity-level system-property="tangosol.coherence.log.level">3</severity-level>
<message-format>{date} Tangosol Coherence {version} <{level}> (thread={thread}, member={member}):      {text}</message-format>
<character-limit system-property="tangosol.coherence.log.limit">4096</character-limit>
</logging-config>
<management-config>

<managed-nodes system-property="tangosol.coherence.management">none</managed-nodes>

<allow-remote-management system-property="tangosol.coherence.management.remote">true</allow-remote-management>
<read-only system-property="tangosol.coherence.management.readonly">false</read-only>
<default-domain-name></default-domain-name>
<service-name>Management</service-name>
</management-config>
</coherence>
Can you attach your config as well, and maybe a
screenshot of the JMX stats?

Hard drive usage / selecting proper hdd for cache & offline lists

As now Spotify uses without any permission my system (win7) drive (C:), which happens to be pretty fully loaded ssd drive.I was just wondering why the F*** is the ssd stacking itself full for "no reason".The reason happened to be Spotifys cache(?), which had grown to over 20GB.Location = C:\users\*****\appdata\local\spotify\data <--- This is the "cache" i wish to get rid of.I would have three additional 2TB hdd:s for this matter, but there is no way to point a location for cache(?) / offlinelists(?) to use.If i remember right, there was an option for this some time ago? Option for selecting spotifys location on hdd:s should be added, as some cases (such as mine) cache usage makesSpotify usage near impossible. Daily cache removal by force, should not be the only solution for product of this grade. I didn't find any other way to get answers or help of any kind for this matter, so i put this in here.There's pretty much none options left on the Spotify and it's hard as hell to give feedback. Improve this

Updated: 2015-08-06Hello and thanks for the feedback!
Any news regarding this request will be announced in the original idea topic here:
https://community.spotify.com/t5/Live-Ideas/Desktop-Actually-bring-back-the-cache-location-and-let-us-limit/idi-p/1167335
Please add your kudos and comments there, if you haven't already. ;)

JPA -- How can I turn off the caching for an entity?

Hi,
I have a problem that I will illustrate with a simplified example. I have created an entity:
@Entity(name="Customer")
@Table(name="CUSTOMERS")
public class Customer implements Serializable {
}I have also set the collowing properties in persistence.xml:
<property name="toplink.cache.type.default" value="NONE"/>
<property name="toplink.cache.size.default" value="0"/>
<property name="toplink.cache.type.Customer" value="NONE"/>
<property name="toplink.cache.size.Customer" value="0"/>
<property name="toplink.cache.shared.Customer" value="false"/>And then I run the following code:
Customer cust = em.find(Customer.class, 1L);
System.out.println(cust);
cust = em.find(Customer.class, 1L);
System.out.println(cust);The problem: the second call to em.find does NOT generate a query to the database. Here's a fragment from the console log:
[TopLink Fine]: 2007.05.11 02:55:05.656--ServerSession(2030438)--Connection(5858953)--Thread(Thread[Main Thread,5,main])--SELECT ID, SEX, NAME, MANAGER FROM CUSTOMERS WHERE (ID = ?)
bind => [1]
Customer: id=1, name=Customer #1, sex=MALE
Customer: id=1, name=Customer #1, sex=MALECan anyone help me? Why isn't the caching turned off? I tried various combinations of properties. Nothing worked. I was expecting to see two queries to the database. I can see only one.
I tried with TopLink Essentials Version 2 Build 39 and Version 2 Build 41.
Best regards,
Bisser

The cache is likely turned off, but you can't tell because you are using the same transactional EntityManager instance for the two queries. The EntityManager requires its own cache for object identity and transactional purposes, as once you read an object in through the EM, the spec requires that all subsequent reads return the same instance. Only the EntityManager refresh will cause a refresh, that or setting your queries to use the toplink.refresh and toplink.cache-usage query hints.
I would strongly recommend you use a query cache for performance, but there are of course reasons why one might not be the best option.
http://weblogs.java.net/blog/guruwons/archive/2006/09/understanding_t.html
is a good blog on understanding the caching used In TopLin Essentials.
Best Regards,
Chris

Lightroom will not accept caches on different drives for multiple catalogs on different drives

I have three catalogs: one for my work files, one for botanical pictures (>200,000 pictures on a network drive) and one for everything else (about 90,000 pics). (i have been forced into this because the keyword files for each set are very large and interfere with the keyword files for the other files.)   Lightroom has become very slow, so I keep the catalogs on different drives, some ssd, some not. I read that you should keep the cache with the catalog. so i changed my preferences to do this. but lightroom insists on using the last cache. so if i switch to my work catalog from my botanical catalog, Lightroom still uses the botanical cache. is there any way to fix this?
(I believe i am using lightroom 64 bit but the title bar only shows lightroom.)
system info
Lightroom version: 5.4 [955652]
Operating system: Windows 7 Ultimate Edition
Version: 6.1 [7601]
Application architecture: x64
System architecture: x64
Logical processor count: 32
Processor speed: 2.2 GHz
Built-in memory: 32751.1 MB
Real memory available to Lightroom: 32751.1 MB
Real memory used by Lightroom: 774.7 MB (2.3%)
Virtual memory used by Lightroom: 732.9 MB
Memory cache size: 117.9 MB
Maximum thread count used by Camera Raw: 32
System DPI setting: 120 DPI
Desktop composition enabled: Yes
Displays: 1) 1920x1200, 2) 1920x1200
Application folder: C:\Program Files\Adobe\Adobe Photoshop Lightroom 5.4
Library Path: D:\LRcat not plants\Lightroom 5 Catalog.lrcat
Settings Folder: I:\Users\rchannon\AppData\Roaming\Adobe\Lightroom
Installed Plugins:
1) Canon Tether Plugin
2) Facebook
3) Flickr
4) rc Reportamus
Config.lua flags: None
Adapter #1: Vendor : 1002
    Device : 6718
    Subsystem : e182174b
    Revision : 0
    Video Memory : 2006

nahcr wrote:
I read that you should keep the cache with the catalog. so i changed my preferences to do this. but lightroom insists on using the last cache.
What cache are you talking about? which preference?
I mean, the only "true" caches I know of are:
ACR cache, whose location is fixed, and
Preview cache, which is *always* with the catalog (unless you go out of your way to link to another drive).
(there is also a "negative" cache, but it's not really exposed to the normal user..).
So, I'm assuming you are talking about the preference to keep presets with catalog, no? But then it still isn't clear what the problem/issue is, or what is the observation about cache usage: "lightroom insists on using the last cache" - what does that mean, how have you concluded it, what did you see?...
You're not confusing presets with a cache are you?
Is this the preference you're talking about?

Named query cache not hit

Hi,
I'm using Toplink ORM 10.1.3.
I have a table called STORE_CONFIG which has a primary key called KEYWORD (a VARCHAR2). The POJO mapped to this table is called StoreConfig.
In the JDeveloper (10.1.3.1.0) mapping workbench I've defined a named query to query by the PK called "getConfigPropertyByKeyword". The type of the named query is ReadObjectQuery.
SELECT keyword, key_value
FROM STORE_CONFIG
WHERE (keyword = #key)
Under the options tab I have the following settings:
Cache Statement: true
Bind Parameters: true
Cache Usage: Check Cache by Primary Key
The application logs show that the same database queries are executed multiple times for the same PK (keyword)! Why is that? Shouldn't it be checking the Object Cache rather than going to the DB?
I've tried it with "Cache Statement: false" and "Bind Parameters: false" with the same problem.
If I click the Advanced tab and check "Cache Query Results" then the database is not hit twice for the same record. However it was my understanding that since I am querying by PK that I wouldn't need to set "Cache Query Results".
Doesn't "Cache Query Results" apply to the Query Cache and not the Object Cache?

Your issue seems to be that you are using custom SQL for the query, not a TopLink expression. When you use an Expression query TopLink's know if the query is by primary key and can get a cache hit.
When you use custom SQL, TopLink does not know that the SQL is by primary key, so does not get a cache hit.
You could either use an Expression for the query,
or when using custom SQL you should be able to name your query argument the same as your database field defined as the primary key in your descriptor (case sensitive).
i.e.
SELECT keyword, key_value
FROM STORE_CONFIG
WHERE (keyword = #KEYWORD)

Finding used space in Oracle Cache

Is there any way to find the size of the buffer cache used to perform a particular query. I want it in exact bytes/blocks. I doesnot mean the maximum buffer cache, but the used buffer cache?

Hi;
What is db version?
please see below thread which could you give some hint to you
buffer cache usage
Buffer Cache Usage
Regard
Helios

Cache usage

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