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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.
GoldenGate supports the following topologies:
The replication configuration consists of the following processes:
Goldengate supports both DML and DDL Replication from the source to target.
The following supplemental logging is required.
Integrated Capture (IC):
The following are the minimum required parameters which must be defined in the extract parameter file.
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.
Oracle Goldengate provides 3 types of Encryption.
You can encrypt a password in OGG using
You can encrypt the password/data using the AES in three different keys
The following are some of the more interesting features of Oracle GoldenGate 12c:
You can install Oracle GoldenGate 12c using in 2 ways:
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).
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
ALTER CREDENTIALSTORE ADD USER userid,
Example: GGSCI> ALTER CREDENTIALSTORE ADD USER GGS@orcl, PASSWORD oracle ALIAS extorcl DOMAIN OracleGoldenGate
GGSCI> INFO CREDENTIALSTORE
GGSCI> INFO CREDENTIALSTORE DOMAIN OracleGoldenGate
In OGG 12c you can encrypt data with the following 2 methods:
The database services required to support Oracle GoldenGate capture and apply must be enabled explicitly for an Oracle 188.8.131.52 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.
In a Coordinated Mode Replicat operates as follows:
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.
You can create the COORDINATED REPLICATE with the following OGG Command:
ADD REPLICAT rfin, COORDINATED MAXTHREADS 50, EXTTRAIL dirdat/et
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.
Yes, Starting with OGG 12c you can now start Extract at a specific CSN in the transaction log or trail.
The parameters below can be used to improve the replicat performance:
The lag and checkpoint latency of the Extract, pump and Replicat processes are normally monitored.
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.
Some of the possible reasons are:
Some of the possible reasons are:
Question 30. My Extract Was Running Fine For A Long Time. All Of A Sudden It Went Down. I Started The Extract Processes After 1 Hour. What Will Happen To My Committed Transactions That Occurred In The Database During Last 1 Hour?
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.
Question 31. I Have Configured Oracle Goldengate Integrated Capture Process Using The Default Values. As The Data Load Increases I See That Extract Starts Lagging Behind By An Hour (or More) And Database Performance Degrades. How You Will Resolve This Performance Issue?
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)
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.
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
Use the following command to view the Extract checkpoint information.
GGSCI> info extract , showch
GGSCI> info extract ext_fin, showch
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.
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.
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.
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
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.
Oracle 184.108.40.206 is the the minimum required database version which supports both Integrated extract and Integrated Reaplicat.
Oracle Integrated Delivery is only available for Oracle Databases.
Yes with 12c, performance statistics are collected in the AWR repository and the data is available via the normal AWR reports.
The steps to be executed would be the following:
It is equivalent of the Oracle database SCN transaction number.
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.
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.
There are 3 basic resources required:
Question 48. I Have A One-way Replication Setup. The System Administration Team Wants To Apply An Os Patch To Both The Ogg Source Host And The Target Servers. Provide The Sequence Of Steps That You Will Carry Before And After Applying This Patch?
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.”)
(Or simply all the extract processes as GGSCI> start extract *)
Use the TRANLOGOPTIONS ARCHIVEDLOGONLY option in the parameter file.
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
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.
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.
Question 53. I Am Migrating My Oracle Database From Non-exadata To Exadata But My Source Ogg Software And Target Ogg Software Versions Are Different (say Source Is Running Ogg 11.1 And Target Is Running Ogg 11.2). How Can I Configure My Ogg Process To Work In Such Configuration?
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.
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
Oracle GoldenGate Related Tutorials
|Oracle 10g Tutorial||Oracle 9i Tutorial|
|Oracle 8i Tutorial||Informatica Tutorial|
|Oracle 11g Tutorial|
Oracle GoldenGate Related Interview Questions
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|Sybase Interview Questions||Oracle Apps ERP Interview Questions|
|Oracle 7.3 Interview Questions||Oracle Access Manager Interview Questions|
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Oracle GoldenGate Related Practice Tests
|Oracle 10g Practice Tests||Oracle 9i Practice Tests|
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|SQL Practice Tests||Oracle apps Practice Tests|
|Sybase Practice Tests||Oracle Apps ERP Practice Tests|
|Oracle 7.3 Practice Tests|
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