Using streams or logical standby

We are runing Oracle 9.2.0.3.0 and have a requirement to replicate the production database on another server for query and reporting purpose.
The changes can be applied to the reporting database on a daily basis. Of course, the faster the better if there is no additional overhead added on the production database (performance acceptable on the production database).
Do you recommend using Oracle Streams or the logical standby database and why? which one is more stable now?
Thanks in advance for your help.

Hi,
there is no difference on the primary site between ADG and normal DG. And there is also no difference in shipment of the redo logs.
The apply performance on the standby is minimally slower (< 2%) and only recognizable if you already have problems that the standby keeps up to date. But then again this does not effect your DR.
It only means that a switchover/failover will take minimally longer....
On the other side, there is always headroom to optimize apply performance. See here:
http://www.oracle.com/technetwork/database/features/availability/maa-wp-11gr1-activedataguard-1-128199.pdf
Regards
Sebastian

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Has anyone performed a successful upgrade from 10.2.0.4 RAC to 11.2.0.2 RAC using a transient logical standby? I found one reference to this white paper "http://www.oracle.com/technetwork/database/features/availability/maa-wp-10gr2-transrollupg-168590.pdf" that describes steps to us transient logical standby to upgrade to 11.1.0.6 but I wasn't sure if it also works for upgrades to 11.2.0.2.
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Hi,
I have a 3 node 10.2.0.4 RAC cluster running on rhel 4.8 with a 3 node dataguard physical standby (which the customer want to keep as a physical standby after the upgrade) that I need to upgrade to 11.2.0.2 with as little downtime as possible. This approach seems like a possible solution but I want to know if it is proven.I suggest you to log a S.R and confirm the same.
thanks,
X A H E E R

Streams Replication: Logical Standby DB as source

I don't have much experience with streams replications. So, the following might sound like a silly questions to Oracle Gurus:
If the source database is a logical standby database, can stream replication be used to replicate some of the tables in the source database to the target DB ?
The source and the target DB are 11g R2.
Thanks in adavance:
- Sanjay
Edited by: sanjayku on Dec 8, 2010 4:38 PM

Never done it, but I don't see any reason why it should not work.
Streams, at capture site, is only a data dictionary game and in a logical standby your data dictionary is open read write.
Streams, at capture site, never touch the source tables, in fact they may even not exists from Streams point of view,
as it deals only with the redo that are generated.
So Streams horizon is limited to the data dictionary, the log buffer, the archives and, in SYSAUX tablespace, all the LOGMNR_% tables. All these structures are read write in the logical standby. However, for the capture/propagation you may have to set to true the 'include_tagged_lcr' parameters.

Best practice on using Flashback and Logical Standby

Hello,
I'm testing a fail-back scenario where I first need to activate a logical standby, then do some dummy transactions before I flashback this db and resme the redo apply. Here is what the steps look like:
1)     Ensure logical standby is in-sync with primary
2)     Enable flashback on standby
3)     Create a flashback guaranteed restore point
4)     Defer log shipping from primary
5)     Activate the logical standby so it’s fully open to read-write
6)     Dummy activities against the standby (which is now fully open)
7)     Flashback the database to the guaranteed checkpoint
8)     Resume log shipping on primary
9)     Resume redo apply on secondary
In the end, i can see the log shipping is happening but the logical standby does not apply any of these..and there is no error in the alert log on Standby side. But the following query could explains why the standby is idle:
SELECT TYPE, HIGH_SCN, STATUS FROM V$LOGSTDBY;
TYPE HIGH_SCN STATUS
COORDINATOR ORA-16240: Waiting for log file (thread# 2, sequence# 0)
ORA-16240: Waiting for log file (thread# string, sequence# string)
Cause: Process is idle waiting for additional log file to be available.
Action: No action necessary. This informational statement is provided to record the event for diagnostic purposes.
I dont understand why it's looking for sequence #0 after the flashback.
Thanks for the help.

Hello;
I hesitate to answer your question because you are not doing a good job of keeping the forum clean :
Total Questions: 13 (13 unresolved)
Please consider closing some of you old answered questions and rewarding those who helped you.
No action necessary.
Do you really have a thread 2? ( Redo thread number )
Quick check
select applied_scn,latest_scn from v$logstdby_progress;Use the DBA_LOGSTDBY_LOG View if you don't have a thread 2 then the sequence# is meaningless.
COLUMN DICT_BEGIN FORMAT A10;
SELECT FILE_NAME, SEQUENCE#, FIRST_CHANGE#, NEXT_CHANGE#,
TIMESTAMP, DICT_BEGIN, DICT_END, THREAD# AS THR# FROM DBA_LOGSTDBY_LOG
ORDER BY SEQUENCE#;Logical Standby questions are difficult, not a lot of them out there I'm thinking.
Check
http://docs.oracle.com/cd/E14072_01/server.112/e10700/manage_ls.htm
"Waiting On Gap State" ( However I still believe you don't have a 2nd thread# )
OR
http://psilt.wordpress.com/2009/04/29/simple-logical-standby/
Best Regards
mseberg
Edited by: mseberg on Apr 26, 2012 5:13 PM

DB_NAME used by the Logical Standby db

Hi all,
It's Oracle 11g R2
I have a general question about converting a Physical standby database to a Logical Standby database.
An important step of the conversion procedure is to issue the following command:
ALTER DATABASE RECOVER TO LOGICAL STANDBY <NEWDBNAME>;
My question is: this statement changes the database name of the Standby database.
How come I still can connect to the new database without having to change the SERVIC_NAME in the tnsnames.ora file?
Here's the connection names used in the file:
db2 =
(DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = oradb2.mydomain.com)(PORT = 1521))
    (CONNECT_DATA =
      (SERVICE_NAME = oradb)
)Here's the new db_name:
SQL> SELECT VALUE FROM V$PARAMETER
WHERE NAME LIKE lower('DB_NAME%')
VALUE
ORADBLS
SQL> conn hr@db2
Enter password:
Connected.

If I understand you correctly, you are asking why changing the database name does not necessitate changing the service name? There is no direct relationship between them, you can define any number of service names to register with the listener. By default, there will be a service that does have the same name as the database (possibly with a domain appended) but you do not have to use that one. Query V$ACTIVE_SERVICES and DBA_SERVICES to see what services are available.
Edited by: JohnWatson on Oct 11, 2012 1:50 PM
Sorry - " a service that does have the same name as the database" should read " a service that does have the same unique name as the database"

When using DataGuard, the logical standby DB is already "OPEN"?

When I was setting up the physical standby DB several years ago no DataGuard got involved), I had the impression that the standby DB is in MOUNT status.
But since when using DataGuard to set up the logical standby DB, the logical standby DB can be used as it is already OPENed.
Is it actually in OPEN status? If so, can the primary and logical standby have the same SID without any trouble?
Please help advise. Thanks a lot!

Hello Christy,
yes it is ok that both database are in status OPEN, that is also the main reason for using logical standby databases (you can do changes and queries on standby too).
I hope you don't use a logical standby database in a SAP environment, because of this is NOT supported. Check sapnote #105047 - Point "14. Data Guard". A logical standby database has limitations.
If you just want to use the physical standby database for queries you can open it in read only or you can use flashback technology for read/write. With Oracle 11g you have these features included in data guard itself (Active Data Guard / Snapshot StandBy) to perform such steps automatically.
Regards
Stefan

Which way - Streams or Logical Standby?

Hi,
I'm having a requirement to replicate a schema between two databases. The scenario is that we've got an Interactive Voice Recorder system for tracking voice calls to a call center contact.
The system will be hosted in two sites, with kind of load balancing where calls are routed to either of the centers. The two centers will each have an OLTP database, and the databases will of-course be similar.
There's a particular schema that needs to be replicated between the two databases so that the schema is available in either of the nodes. We were thinking of Active Standby but this seems to be out of question because the two databases need to be open read-write all the time.
We are looking into Streams to accomplish this, but we wonder if a logical standby can also accomplish the same, since it can be open read-write?
The database version will be 11.1.0.7.0

user11983948 wrote:
Thanks Anuraq,
The volume of the data that will be replicated will be small, just a single schema. I also did not clarify, but the data in the two databases will be kept only for about 30 days, then truncated, after being sent to a separate warehouse server where the data will be stored and analyzed.
Regards,
dulaIf the data replicated is small, and dmls are free then streams would be better than logical standby.
Regarding the truncate part you meant the data would be deleted from the table which are older than 30 days. Streams would be able to handle that. Make sure you delete the data from one site only and that would be replicated on another site. I also assume you are looking for two way replication in that case logical standby is not an option.
Regards
Anurag

Streams or Logical Standby?

I have a requirement to duplicate an Oracle DB over a WAN to a remote site. The data in that copy of the DB (along with many other databases of various platforms) will then be aggregated into a SQL Server database for reporting purposes.
The requirements are:
- there can be no noticeable performance impact on the primary DB
- the secondary DB must be as close to in sync with the primary as possible (i.e. little or no lag)
- the secondary DB must be readable at all times (precludes max performance physical standby)
Current configuration
- the primary is an 11.2.0.1 RAC database.
- there is already a physical standby at the remote site for DR purposes operating in maximum performance mode and using standby logs. It rarely falls more than 2-3 seconds behind the primary. If this server could be leveraged that would be great, but obviously a physical standby cannot be both readable and up to date.
TIA

Hi,
there is no difference on the primary site between ADG and normal DG. And there is also no difference in shipment of the redo logs.
The apply performance on the standby is minimally slower (< 2%) and only recognizable if you already have problems that the standby keeps up to date. But then again this does not effect your DR.
It only means that a switchover/failover will take minimally longer....
On the other side, there is always headroom to optimize apply performance. See here:
http://www.oracle.com/technetwork/database/features/availability/maa-wp-11gr1-activedataguard-1-128199.pdf
Regards
Sebastian

Slow SQL Apply on Logical Standby Database in Oracle10g

Hi,
We are using Oracle 10g Logical Standby database in our production farm but whenever there is bulk data load (5-6 GB data) on the primary database, the logical standby seems to be hung. It takes days to apply the 5-6 GB data on the logical standby.
Can anybody give me some pointers how can I make my SQL Apply fast on the logical standby for bulk data.
Thanks
Amit

Hi there,
I've a similar problem. I did an insert of 700k on a table. It takes me over 1 1/2 hours to see the data. Notice, I increased the "max_sga" to 300m and "max_servers" to 25" and didn't help the performance at all.
My version is 10.2.0.3 with the patch 6081550.
APPLIED_SCN APPLIED_TIME RESTART_SCN RESTART_TIME LATEST_SCN LATEST_TIME MINING_SCN MINING_TIME
1015618 29-NOV-2007 18:28:51 1009600 29-NOV-2007 18:28:51 1017519 29-NOV-2007 19:54:07 1015656 29-NOV-2007 18:32:14

Logical standby performance

Hi,
Will there be any performance impact when using SQL apply logical standby database compared to direct redo apply physical standby database? Let's take we are doing some bulk delete(around 10k) in primary, will there be any more time lag when replicate to LSDB.
Note: Both primary and LSDB are within the same datacenter.
Thanks,
Srini

Hi,
Physical standby works in a simple way – it applies directly (as a recovery would) the changes from the archive log to the respective data blocks. The physical standby typically enjoys smooth and predictable operation. If the physical standby works on a hardware as powerful as the primary’s, it would likely not be a bottleneck.
Logical standby is very different animal altogether!
Not all databases can have LSDB. There are certain data types that are not supported in LSDB (the list depends on the DB version).
To be able to operate reasonably fast, LSDB would require every medium or large table to have primary key (or at least unique index).
Direct insert and parallel DML are not honored by the LSDB.
Batch processes would be processed row-by-row (and get slower as a result of that).
Getting consistently good performance (and no lag) from LSDB requires concerted efforts and cannot be taken for granted even when the LSDB is run on a “primary” hardware.

Transportable tablespaces with Logical Standby

Does anyone know whether or not transportable tablespaces can be used in a Logical Standby environment? I know they can be used with a Physical Standby, and the documentation covers how to do this, but there's nothing about Logical Standby. This is Oracle 10.2.0.4/SLES 10.
Thanks.

Using transportable tablespaces to a logical standby environment. Actually, there is a paragraph in the 10.2 Data Guard Concepts and Administration manual. I will summarize:
After creating the transportable tablespace export file on the source system, copy the datafiles to both the primary and logical standby systems.
On the dataguard logical standby, within SQLplus, issue SQL> alter session disable guard;
Import the tablespaces into the logical standby database
SQL> alter session enable guard;
Import the tablespaces into the primary database.
In 10.1, we imported the tablespaces into an environment with a physical standby and then converted the physical standby to a logical standby.
I tested the procedure for 10.2 and it seemed to work. Has anyone else done this and if so, are you aware of any issues? Like I said, the documentation is one very brief paragraph.
Thanks.

Oracle Logical Standby as data source

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CA Forum: Data Connectivity and SQL
Has anyone succesfully used an Oracle Logical Standby server as a
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Logical Standby and Streams

Hi,
I am considering different replication scenarios for our future system and have a (maybe stupid:) question. Is it technically possible to create a logical standby database (Data Guard) and than replicate it further using Streams?
Regards,
Tim

Yes , This is possible with logical standby but you need to have mechanisms to take care of role transitioning in case of fail over. See Oracle document http://download.oracle.com/docs/cd/E14072_01/server.112/e10700/whatsnew.htm (Key word search "streams")
Thanks
http://swervedba.wordpress.com/
Edited by: swervedba on May 30, 2011 8:48 PM

Logical Standby SQL Apply Using Incorrect Decode Statement

We are seeing statements erroring out on our logical standby that have been rewritten (presumably by sql apply) with decode statements that don't appear to be correct. For example, here is one of the rewritten statements.
update /*+ streams restrict_all_ref_cons */ "CADPROD"."OMS_SQL_STATEMENT" p
set *"APPLICATION"=decode(:1,'N',"APPLICATION",:2)*,
"STATEMENT"=dbms_reputil2.get_final_lob(:3,"STATEMENT",:4)
where (:5='N' or(1=1 and (:6='N' or(dbms_lob.compare(:7,"STATEMENT")=0)or(:7 is null and "STATEMENT" is null)))) and(:8="APPLICATION")
The problem comes in, we believe, with the attempt to write the value "APPLICATION" to the application column which is only a 10 character field. the value for the :1 bind variable is "N" and the value for :2 is null.
We see the following error on the logical standby:
ORA-00600: internal error code, arguments: [kgh_heap_sizes:ds], [0x01FCDBE60], [], [], [], [], [], []
ORA-07445: exception encountered: core dump [ACCESS_VIOLATION] [kxtoedu+54] [PC:0x2542308] [ADDR:0xFFFFFFFFFFFFFFFF] [UNABLE_TO_READ] []
ORA-12899: value too large for column "CADPROD"."OMS_SQL_STATEMENT"."APPLICATION" (actual: 19576, maximum: 10)
Is this a configuration issue or is it normal for SQL Apply to convert statements from logminer into decode statements?
We have an Oracle 10.2.0.4 database running on windows 2003 R2 64-bit os. We have 3 physical and 2 logical standby's, no problems on the physical standbys.

Hello;
I noticed some of your parameters seem to be wrong.
fal_client - This is Obsolete in 11.2
You have db_name='test' on the Standby, it should be 'asadmin'
fal_server=test is set like this on the standby, it should be 'asadmin'
I might consider changing VALID_FOR to this :
VALID_FOR=(ONLINE_LOGFILES,ALL_ROLES)Would review 4.2 Step-by-Step Instructions for Creating a Logical Standby Database of Oracle Document E10700-02
Document 278371.1 is showing its age in my humble opinion.
-----Wait on this until you fix your parameters----------------------
Try restarting the SQL Apply
ALTER DATABASE START LOGICAL STANDBY APPLY IMMEDIATEI don't see the parameter MAX_SERVERS, try setting it to 8 times the number of cores.
Use these statements to trouble shoot :
SELECT NAME, VALUE, UNIT FROM V$DATAGUARD_STATS;
SELECT NAME, VALUE FROM V$LOGSTDBY_STATS WHERE NAME LIKE ;TRANSACTIONS%';
SELECT COUNT(1) AS IDLE_PREPARERS FROM V$LOGSTDBY_PROCESS WHERE
TYPE = 'PREPERER' AND STATUS_CODE = 16166;Best Regards
mseberg
Edited by: mseberg on Feb 14, 2012 7:37 AM

DATA Guard Logical Standby v.s. Streams Apply (10gR2, rac -- rac )

Greetings -
We currently have a 3 node cluster, doing a 'Schema' capture, with a 2 node cluster serving as the apply side. Both are on 10gR2 (solaris 10)
We have been experiencing apply latency due to large transactions. The way logminer/streams evaluates the arch logs, it converts each updated row into a transaction as part of a transaction set, using 'decode (' statements.
I am under the impression a physical standby will do the same thing. But what about a logical Standby ?
(this from the Oracle Documentation)
[10g Concepts|http://download.oracle.com/docs/cd/B19306_01/server.102/b14239/concepts.htm#SBYDB00010]
...Contains the same logical information as the production database, although the physical organization and structure of the data can be different. The logical standby database is kept synchronized with the primary database though SQL Apply, which transforms the data in the redo received from the primary database into SQL statements and then executing the SQL statements on the standby database.
Does anyone know firsthand if SQL APPLY re-issues the original sql, or if it relies on the 'decode' command as well ?
Thanks
The Nets Edge

A Physical standby does not do anything with SQL. It is running media recovery under the covers. A Logical standby uses the Logminer to read the redo, converts it to SQL and Data and applies those transactions to the Logical standby.
The both build logical change records, figure out order, dependencies etc etc and applies the transaction. Both are susceptible to long running transactions on the Primary (source) database.
Streams uses Logminer, Logical Standby use part of the Streams apply so as Mr. Morgan said, they are very similar :^)
If you are having apply performance issues you may want to look at Active data Guard.
Larry

Using streams or logical standby

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