Ignoring cache - selecting directly from database

I have a scenario where several tables will be mapped using Toplink for the data access benefits, but will be updated ouside of the Toplink process. Obviously this behavior negates the beneift of caching in toplink and I need a reliable way to bypass the cache when selecting from these tables.
The only method I've found in my testing to overcome this problem is to select "Always Refresh" and "Disable Cache Hits" on the related entities in the Toplink Mapping Workbench. All other configurations, including setting the identity map size to 0 will return stale instances of these objects.
I've also tried invoking dontCheckCache() and setCacheUsage() on my query with the understanding, based on the API documentation, that the cache would be ignored for the query. In both cases the returned object was retrieved from the cache and not the database.
While the workbench solution will suffice for my purposes, I would like to know if there are other methods of ignoring the cache. Also, I'm curious about why the query methods I've mentioned don't seem to have any affect on the source of the resulting objects.
I am using Toplink v9.0.3

Using "Always Refresh" and "Disable Cache Hits" is probably the best method to ensure that no cached data is every returned from queries. If you are using optimistic locking you may also use "onlyRefreshCacheIfNewerVersion" in conjunction with these.
For the full/weak identity maps the size is only the default map size, it will grow as objects are added, so setting this to 0 will have no effect on what is cached, you could set the cache type to NoIdentityMap ("None") to achieve this, but usage of alwaysRefreshCache is a better way as is still preserves object identity.
The query options dontCheckCache() and setCacheUsage() are in-memory querying options, they effect how cache hits are obtained, but do not effect how the objects are cached or refreshed. To refresh objects at the query level use refreshIdentityMapResult() ("Refresh"). Using refresh at the query level should also meet your needs, and may be better than setting the alwaysRefreshCache option on the descriptor as then you can control which queries refresh and which can obtain cache hits. (for example you may want to query for employees to refresh, but allow the query for the 1-1 backreference for phone numbers to obtain a cache hit). For refresh queries you can also set the refresh cascade depth.

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Select data from DataBase

Hi;
I try to select data from DataBase, But I get the following error, Could anyone help? thanks.
Exception in thread "main" java.lang.ClassNotFoundException: oracle.jdbc.driver.
OracleDriver
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at Lookup.main(Lookup.java:12)
import java.sql.*;
import java.io.*;
import java.util.*;
public class Lookup {
 public static void main(String[] args)
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It's a classpath problem. Either you mistyped the class name, or you don't have the class in your classpath. I think Oracle's drivers come in db12.zip or db12.jar or some such. Whatever that jar or zip file is, it has to be in your classpath, but it's not.
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How to select rows from database like 10 to 20 etc

Hi Experts,
I want to select rows from database like row number 10 to row number 20.How could it be done?

HI,
 First get the data into the INTERNAL TABLE from the FLAT FILE and read the internal table using the index.
 ex: 1) Read table ITAB index 10.
 2) Read table ITAB index 20.
or use as said by Srinivas Gurram, to get the range of records using where condition to the loop.
<REMOVED BY MODERATOR>
Edited by: Ravi Kumar on Jun 9, 2008 4:01 PM
Edited by: Alvaro Tejada Galindo on Jun 9, 2008 3:16 PM

Caching data read from database

I have a big performace problem in our J2EE application. We use jsp and servlets to process a request. Servlet gets the results from database which are stored in a vector of dataobjects and vector is stored in session. We display only 20 rows in jsp and provide page navigation to view more data by Next and Prev links. The problem is we want to store results in request object instead of session variable but then that data is not availabe for Next and Prev links. We don't want to do another search to view more data. Is there a way to cache the data so that while view more data by page navigation we don't need to hit database since request object would be cleared at that time. I am clueless. I hope I explained the problem properly. Any help on this would be highly appreciated

You're not clueless, you said it yourself.
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hi all,
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hw to increase the performance.
kindly, reply.
thnks

Also Check you are not using open sql much like distict order by group by , use abap techniques on internal table to acive the same.
also Dont use select endselect.
if possible use up to n rows claus....
taht will limit the data base hits.
also dont run select in siode any loops.
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Hi,
We use the command "select text from user_source where name = 'XXX';" to
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Hi,
Try this code. I think this will solve your problem. Spool the text to a file as it may be difficult for you to read from the SQL prompt.
SPOOL <LOCATION OF THE FILE>
set long 50000;
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Jaikanth V Garlapati.

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I have just installed odac beta (ODAC1120250Beta_EntityFramework) and Orace XE 11g for test.
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A couple of things you could try:
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Hi ,
I ahve a database view with some fields.
Now my requirement is to serach a single row on the basis of process type.
Process type can have values like ZBA,ZBC,ZBD,ZBE or similarly anything starting with ZB.
Now i know that starting two letters will be ZB , but dont knwo the last letter.
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Should i use like operator for the same?
regards
PG

hi,
u can use character '%'.sample code like this
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I've got the file uploading to the database, and that is working most excellent.
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<cfheader name="content-type" value="application/octet-stream">
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^_^

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Select double * from database table?

Hi,
See the entries in the following database table.
TABLE1
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AB   12    de    effd    32e
CD   34    fr      wref   45fr
EF   34    rfr      wfrf    wfwrf
Here I need to get the two values of F1 field. Those are AB and CD into two separate variables.
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--Naveen Inuganti.

Hi ,
Check the code , it will resolve the issue --
DATA : w_variable2 TYPE scarr-carrid,
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From your reference I created single silect query without internel table - -
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I want to select data for display and insert data to tables via XML, and I want
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The oracle documentation says I need the following in order to do this.
1. XML-SQL Utility
2. XML Parser for Java, V2
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4. JDK
5. A Java compliant web server
6. XSL Servlet
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What are all available within the database and what are other software I need to
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It's a classpath problem. Either you mistyped the class name, or you don't have the class in your classpath. I think Oracle's drivers come in db12.zip or db12.jar or some such. Whatever that jar or zip file is, it has to be in your classpath, but it's not.
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Select record from database table

how to select a record from data-base table for current month in module-pool, i.e if current month is august then records selected should between 1/08/10 to 31/08/10.
And, i also want to select records for last month i.e if current month is august then records selected should be between 1/07/10 to 31/07/10.
And one thing more, it should work for every scenario. Like for months are changing then it should work according to that.
Example: If month changes to October then current month ll be October and last month ll become September.
Plz help me out.
Moderator message: you chose a better forum this time, but the question is still too basic to be asked here, please (re)search yourself first, these forums are not catering to beginners.
locked by: Thomas Zloch on Aug 8, 2010 9:41 PM

Hi Nishant,
You can use the option ORDER BY in your SELECT clause.
This is the SAP Documentation for ORDER BY option.
Variant 1
...ORDER BY PRIMARY KEY
Effect
Sorts the selected lines in ascending order by the primary key of the database table. This variant is only permitted for SELECT * ....
Notes
Since views do not have a primary key, specifying ORDER BY PRIMARY KEY only makes sense with database tables. If, however, you do specify ORDER BY PRIMARY KEY with a view, all fields of the view are sorted in ascending order.
Variant 2
ORDER BY f1 ... fn
Effect
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By supplementing the statement with DESCENDING, you can sort in descending order using any of the fields f1, ..., fn.
The default sort sequence is ascending order, but you can make this explicit by adding the addition ASCENDING.
Consider this code this will select the latest 10 records form DB table(Note can use Variant 2 for DB tables also.
REPORT zarun_1.
DATA : it_mara TYPE STANDARD TABLE OF mara WITH HEADER LINE.
START-OF-SELECTION.
SELECT * FROM mara
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LOOP AT it_mara.
 WRITE : / it_mara-matnr,
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ENDLOOP.
Regards,
Arun Sambargi.
Message was edited by: Arun Sambargi

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Ignoring cache - selecting directly from database

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