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Do you like to switch your career? Here's our recommendation on the important things to need to prepare for the job interview to achieve your career goals in an easy way. Oracle GoldenGate makes sure the data is transactional and delivered across environments. If any new data is captured from the source, it will automatically apply the functions that need to be done and sends it across target. Candidate should have good command on all activities to be done. There is huge demand for jobs related to Oracle GoldenGate anywhere. One can check the availability of the job across cities including Mumbai, Delhi, Bangalore, Pune and Hyderabad. Follow Wisdomjobs page for Oracle GoldenGate job interview questions and answers page to get through your job interview successfully.
Question 1. What Type Of Topology Does Goldenggate Support?
Answer :
GoldenGate supports the following topologies:
Question 2. What Are The Main Components Of The Goldengate Replication?
Answer :
The replication configuration consists of the following processes:
Question 3. What Transaction Types Does Goldengate Support For Replication?
Answer :
Goldengate supports both DML and DDL Replication from the source to target.
Question 4. What Are The Supplemental Logging Pre-requisites?
Answer :
The following supplemental logging is required.
Question 5. Why Is Supplemental Logging Required For Replication?
Answer :
Integrated Capture (IC):
Question 6. List The Minimum Parameters That Can Be Used To Create The Extract Process?
Answer :
The following are the minimum required parameters which must be defined in the extract parameter file.
Answer :
Only one Extract process can write to one exttrail at a time. So you can’t configure multiple extracts to write to the same exttrail.
Question 8. What Type Of Encryption Is Supported In Goldengate?
Answer :
Oracle Goldengate provides 3 types of Encryption.
Question 9. What Are The Different Password Encryption Options Available With Ogg?
Answer :
You can encrypt a password in OGG using
Question 10. What Are The Different Encryption Levels In Aes?
Answer :
You can encrypt the password/data using the AES in three different keys
Question 11. What Are Some Of The Key Features Of Goldengate 12c?
Answer :
The following are some of the more interesting features of Oracle GoldenGate 12c:
Question 12. What Are The Installation Options Available In Ogg 12c?
Answer :
You can install Oracle GoldenGate 12c using in 2 ways:
Question 13. What Is A Credential Store In Ogg 12c?
Answer :
OGG Credential Store manages Encrypted Passwords and USERIDs that are used to interact with the local database and Associate them with an Alias. Instead of specifying actual USERID and Password in a command or a parameter file, you can use an alias. The Credential Store is implemented as an auto login wallet within the Oracle Credential Store Framework (CSF).
Question 14. How To Configure Credential Store In Ogg 12c?
Answer :
Steps to configure Oracle Credential Store are as follows:
If you want to specify a different location use can specidy “CREDENTIALSTORELOCATION” parameter in GLOBALS file.
Example: CREDENTIALSTORELOCATION /u01/app/oracle/OGG_PASSWD
cd $OGG_HOME
./ggsci
GGSCI>
Question 15. What Command Is Used To Create The Credential Store?
Answer :
ADD CREDENTIALSTORE.
Question 16. How Do You Add Credentials To The Credential Store?
Answer :
ALTER CREDENTIALSTORE ADD USER userid,
[PASSWORD password]
[ALIAS alias]
[DOMAIN domain]
Example: GGSCI> ALTER CREDENTIALSTORE ADD USER GGS@orcl, PASSWORD oracle ALIAS extorcl DOMAIN OracleGoldenGate
Question 17. How Do You Retrieve Information From The Oracle Credential Store?
Answer :
GGSCI> INFO CREDENTIALSTORE
OR
GGSCI> INFO CREDENTIALSTORE DOMAIN OracleGoldenGate
Question 18. What Are The Different Data Encryption Methods Available In Ogg 12c?
Answer :
In OGG 12c you can encrypt data with the following 2 methods:
Question 19. How Do You Enable Oracle Goldengate For Oracle Database 11.2.0.4?
Answer :
The database services required to support Oracle GoldenGate capture and apply must be enabled explicitly for an Oracle 11.2.0.4 database. This is required for all modes of Extract and Replicat.
To enable Oracle GoldenGate, set the following database initialization parameter. All instances in Oracle RAC must have the same setting.
ENABLE_GOLDENGATE_REPLICATION=true
Question 20. How Does The Replicat Works In A Coordinated Mode?
Answer :
In a Coordinated Mode Replicat operates as follows:
Question 21. What Is The Difference Between Classic And Coordinated Replicat?
Answer :
The difference between classic mode and coordinated mode is that Replicat is multi-threaded in coordinated mode. Within a single Replicat instance, multiple threads read the trail independently and apply transactions in parallel. Each thread handles all of the filtering, mapping, conversion, SQL construction, and error handling for its assigned workload. A coordinator thread coordinates the transactions across threads to account for dependencies among the threads.
Question 22. How Do You Create A Coordinated Replicate In Ogg 12c?
Answer :
You can create the COORDINATED REPLICATE with the following OGG Command:
ADD REPLICAT rfin, COORDINATED MAXTHREADS 50, EXTTRAIL dirdat/et
Answer :
Starting with OGG 12c, if you don’t specify a DISCARDFILE OGG process now generates a dicard file with default values whenever a process is started with START command through GGSCI.
Question 24. Is It Possible To Start Ogg Extract At A Specific Csn?
Answer :
Yes, Starting with OGG 12c you can now start Extract at a specific CSN in the transaction log or trail.
Example:
Question 25. List A Few Parameters Which May Help Improve The Replicat Performance?
Answer :
The parameters below can be used to improve the replicat performance:
Question 26. What Are The Areas To Monitor In Goldengate Replication?
Answer :
The lag and checkpoint latency of the Extract, pump and Replicat processes are normally monitored.
Question 27. What Is The Passthru Mode Used For?
Answer :
In pass-through mode, the Extract process does not look up the table definitions, either from the database or from a data definitions file. This increases the throughput of the data pump, as the object definition look-up is bypassed.
Question 28. What Are The Most Common Reasons Of An Extract Process Slowing Down?
Answer :
Some of the possible reasons are:
Question 29. What Are The Most Common Reasons Of The Replicate Process Slowing Down?
Answer :
Some of the possible reasons are:
Answer :
OGG checkpoint provides the fault tolerance and make sure that the transaction marked for committed is capture and captured only once. Even if the extract went down abnormally, when you start the process again it reads the checkpoint file to provide the read consistency and transaction recovery.
Answer :
When operating in integrated capture mode, you must make sure that you have assigned sufficient memory to STREAMS_POOL_SIZE. An undersized STREAMS_POOL_SIZE or limiting the streams pool to use a specific amount of memory can cause troubles.
The best practice is to allocate STREAMS_POOL_SIZE at the instance level and allocate the MAX. SGA at GG process level as below:
SQL> alter system set STREAMS_POOL_SIZE=3G
TRANLOGOPTIONS INTEGRATEDPARAMS (MAX_SGA_SIZE 2048, PARALLELISM 4)
Question 32. Why Would You Segregate The Tables In A Replication Configuration? How Would You Do It?
Answer :
In OGG you can configure replicat at the data at the schema level or at the table level using TABLE parameter of extract and MAP parameter of replicat.
For replicating the entire database you can list all the schemas in the database in the extract/replicat parameter file.
Depending the amount of redo generation you can split the tables in a schema in multiple extracts and replicats to improve the performance of data replication. Alternatively youcan also group a set of tables in the confiuration by the application functionality.
Alternatively you may need to remove tables which have long running transactions in a seperate extract process to eliminte lag on the other tables.
Let’s say that you have a schema named SCOTT and it has 100 hundred tables.
Out of these hundred tables, 50 tables are heavily utilized by application.
To improve the overall replication performance you create 3 extract and 3 replicats as follows:
Ext_1/Rep_1 –> 25 tables
Ext_2/Rep_2 –> 25 tables
Ext_3/Rep_3 –> 50 tables
Ext_1/Rep_1 and Ext_2/Rep_2 contains 25 table each which are heavily utilized or generate more redo.
Ext_3/Rep_3 contains all the other 50 tables which are least used.
Question 33. How Can We Report On Long Running Transactions?
Answer :
The WARNLONGTRANS parameter can be specified with a threshold time that a transaction can be open before Extract writes a warning message to the ggs error log.
Example: WARNLONGTRANS 1h, CHECKINTERVAL 10m
Question 34. What Command Can Be Used To View The Checkpoint Information For The Extract Process?
Answer :
Use the following command to view the Extract checkpoint information.
GGSCI> info extract , showch
GGSCI> info extract ext_fin, showch
Question 35. How Is The Restartcollision Parameter Different From Handlecollisions?
Answer :
The RESTARTCOLLISION parameter is used to skip ONE transaction only in a situation when the GoldenGate process crashed and performed an operation (INSERT, UPDATE & DELETE) in the database but could not checkpoint the process information to the checkpoint file/table. On recovery it will skip the transaction and AUTOMATICALLY continue to the next operation in the trail file.
When using HANDLECOLLISION GoldenGate will continue to overwritten and process transactions until the parameter is removed from the parameter files and the processes restarted.
Question 36. How Do You View The Data Which Has Been Extracted From The Redo Logs?
Answer :
The logdump utility is used to open the trail files and look at the actual records that have been extracted from the redo or the archive log files.
Answer :
This occurs when the V$ARCHIVED_LOG.NEXT_CHANGE# is greater than the SCN required by the GoldenGate Capture process and RMAN is trying to delete the archived logs. The RMAN-08147 error is raised when RMAN tries to delete these files.
When the database is open it uses the DBA_CAPTURE values to determine the log files required for mining. However if the database is in the mount state the V$ARCHIVED_LOG. NEXT_CHANGE# value is used.
Question 38. How Would You Look At A Trail File Using Logdump, If The Trail File Is Encrypted?
Answer :
You must use the DECRYPT option before viewing data in the Trail data.
List few useful Logdump commands to view and search data stored in OGG trail files.
Below are few logdump commands used on a daily basis for displaying or analyzing data stored in a trail file.
$ ./logdump – to connect to the logdump prompt
logdump> open /u01/app/oracle/dirdat/et000001 – to open a trail file in logdump
logdump> fileheader on – to view the trail file header
logdump> ghdr on – to view the record header with data
logdump> detail on – to view column information
logdump> detail data – to display HEX and ASCII data values to the column list
logdump> reclen 200 – to control how much record data is displayed
logdump> pos 0 – To go to the first record
logdump> next (or simply n) – to move from one record to another in sequence
logdump> count – counting records in a trail
Question 39. Why Should I Upgrade My Goldengate Extract Processes To Integrated Extract?
Answer :
Oracle is able to provide faster integration of the new database features by moving the GoldenGate Extraction processes into the database. Due to this, the GoldenGate Integrated Extract has a number of features like Compression which are not supported in the traditional Extract. You can read more about how to upgrade to Integrated Extract and more about Integrated Delivery. Going forward preference should be give to create new extracts as Integrated Extracts and also to upgrade existing traditional Extracts.
Question 40. What Is The Minimum Database Version Which Supports Integrated Delivery?
Answer :
Oracle 11.2.0.4 is the the minimum required database version which supports both Integrated extract and Integrated Reaplicat.
Question 41. What Databases Supports Goldengate Integrated Delivery?
Answer :
Oracle Integrated Delivery is only available for Oracle Databases.
Question 42. With Integrated Delivery, Where Can We Look For The Performance Stats?
Answer :
Yes with 12c, performance statistics are collected in the AWR repository and the data is available via the normal AWR reports.
Question 43. What Are The Steps Required To Add A New Table To An Existing Replication Setup?
Answer :
The steps to be executed would be the following:
Question 44. What Does The Goldengate Csn Equate To, In The Oracle Database?
Answer :
It is equivalent of the Oracle database SCN transaction number.
Question 45. How Do You Create A Csv File From The Extracted Data?
Answer :
You will have to use the CSV Flat File Adaptor to create CSV files. The source would be the extract trail files which use the configuration of the adaptor settings to generate CSV files.
Question 46. What Is The Purpose Of The Defgen Utility?
Answer :
When the source and the target schema objects are not the same (different DDL’s) the Replicat process needs to know the source definition of the objects. The output from the DEFGEN utility is used in conjunction with the trail data to determine which column value in the trail belongs to which column.
Answer :
There are 3 basic resources required:
Answer :
Procedure:
GGSCI> send extract , logend
(The above command should print YES)
GGSCI> send extract , getlag
GGSCI> send extract , getlag
GGSCI> send replicat , getlag
(The above command should pring “At EOF, no more records to process.”)
Source:
Target:
Source:
(Or simply all the extract processes as GGSCI> start extract *)
Target:
Answer :
Use the TRANLOGOPTIONS ARCHIVEDLOGONLY option in the parameter file.
Question 50. What Is The Best Practice To Delete The Extract Files In Ogg?
Answer :
Use the manager process to delete the extract files after they are consumed by the extract/replicat process
PURGEOLDEXTRACTS /u01/app/oracle/dirdat/et*, USECHECKPOINTS, MINKEEPHOURS 2
Answer :
OGG by default assumes that the sources and target tables are identical. A table is said to be identical if and only if the table structure, data type and column order are the same on both the source and the target.
If the tables are not identical you must use the parameter ‘SOURCEDEFS’ pointing to the source table definition and ‘COLMAP’ parameter to map the columns from source to target.
Question 52. What Are The Different Ogg Initial Load Methods Available?
Answer :
OGG has 2 functionalities, one it is used for Online data Replication and second for Initial Loading.
If you are replicating data between 2 homogeneous databases then the best method is to use database specific method (Exp/Imp, RMAN, Transportable tablespaces, Physical Standby and so on). Database specific methods are usually faster than the other methods.
—If you are replicating data between 2 heterogeneous databases or your replicat involves complex transformations, then the database specific method can’t be used. In those cases you can always use Oracle GoldenGate to perform initial load.
Within Oracle GoldenGate you have 4 different ways to perform initial load.
Oracle GoldenGate initial loading reads data directly from the source database tables without locking them. So you don’t need downtime but it will use database resources and can cause performance issues. Take extra precaution to perform the initial load during the non-peak time so that you don’t run into resource contention.
Answer :
It is recommended that all instances of Oracle GoldenGate be the same version to take advantage of the new functionality, but this is not possible all the time and is not required. In this scenario, OGG provides a parameter called ‘FORMAT RELEASE’ which allows customers to use different versions of Oracle GoldenGate Extract, trail files, and Replicat together.
Example: RmtTrail /u01/app/oracle/dirdat, Format Release 11.1
Note: The input and output trails of a data pump must have the same trail file version.
Answer :
You must use OGG 11.2 and configure GoldenGate Integrated Capture process to extract data from compressed tables.
Note: Pre OGG 11.2 doesn’t support extracting data from compressed tables
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