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Bi-directional configuration options in Software Printing Code 39 Full ASCII in Software Bi-directional configuration options




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Bi-directional configuration options use software 3 of 9 barcode implement toinsert code 3/9 with software ASP.NET Web Forms Loop d Software barcode code39 etection Conflict detection Conflict resolution Replicating Oracle sequences Oracle triggers. When implementing a b i-directional configuration, you must consider the following areas to avoid data integrity issues. These are as follows:. Let"s take a look at the first potential problem, data looping, and how to detect it. [ 112 ]. 5 . GoldenGate has built- in loop detection, which is configured through the IGNOREREPLICATES and GETAPPLOPS parameters to prevent local transactions from being replicated and causing endless loops. Another solution would be the TRANLOGOPTIONS EXCLUDEUSER parameters in the Extract process configuration, effectively blocking the GGS_ADMIN user on the target system (the user associated with the Replicat process). However, loop detection is only half the battle in a bidirectional environment.

We must also consider conflict detection and resolution.. Truncate table operat Software Code 39 ions cannot be detected by the loop detection scheme. To combat this, ensure the GETTRUNCATES is ON in only one direction, that is, source to target..

Loop detection Loop detection is discussed in more detail in 7, Advanced Configuration. Conflict detection Conflicts occur in a Code-39 for None bi-directional environment when the same row in a given table is updated around the same time on both sites. GoldenGate does not have a built-in conflict detector and must be hand crafted if you wish to address this issue. Which transaction will succeed Should they both fail These are both valid questions and must be answered before you go ahead and code your conflict handler.

GoldenGate is renowned for its low latency, which helps to alleviate any conflicts. However, the best solution would be at the application level, segregating users at the different locations, only allowing each group to update specific ranges of records in tables and thus avoiding conflicts. This is sometimes not possible and conflict detection and resolution must be employed.

The key to conflict detection is the before image in an UPDATE operation. As we know, GoldenGate can store the before image and evaluate it against the existing value in the target row. The following example shows the use of SQLEXEC, which is used initially to obtain the existing value in the target table, and then compared to the before image from the source table by the BEFORE and CHECK parameters of the FILTER clause:.

REPERROR (9999, EXCEP TION) MAP SRC.CREDITCARD_PAYMENTS, TARGET TGT.CREDITCARD_PAYMENTS, & SQLEXEC (ID CHECK_CONFLICT, ON UPDATE, BEFOREFILTER, & QUERY "SELECT PAYMENT FROM TGT.

CREDITCARD_PAYMENTS & WHERE ID = :P1", & PARAMS (P1 = ID)), & [ 113 ]. Configuration Options Code 39 for None FILTER (ON UPDATE, BEFORE.PAYMENT <> CHECK.PAYMENT, & RAISEERROR 9999); INSERTALLRECORDS MAP SRC.

CREDITCARD_PAYMENTS, TARGET TGT.EXCEPTIONS, EXCEPTIONSONLY, & COLMAP (USEDEFAULTS, ERRTYPE = "Conflict Detected");. The BEFOREFILTER para meter of SQLEXEC allows the SQL to execute before the FILTER statement, enabling the results to be used in the filter.. Conflict resolution The method behind con flict detection and resolution is discussed in 10, Troubleshooting GoldenGate in the "Exception Handling" section. Once you have a mechanism to detect conflicts, you need to resolve them based on your business rules. The following is a list of four possible options: 1.

Apply the net difference instead of the after image. 2. Map the data to an exception table for manual resolution.

3. Apply the latest update from either source. 4.

Discard the change. All the above can be configured to execute automatically via GoldenGate parameter files except option 2. This has to be manually determined quickly as subsequent updates may also suffer conflicts.

It is therefore good practice to have an Event Action to alert the GoldenGate Administrator when an INSERT operation on the Exceptions table occurs. This is shown in the following Replicat configuration example:. TABLE TGT.EXCEPTIONS, Software 3 of 9 barcode & FILTER (@GETENV ("GGHEADER", "OPTYPE") = "INSERT"), & EVENTACTIONS (SHELL /home/oracle/scripts/email_alert.sh);.

Oracle sequences GoldenGate does not s Software 3 of 9 barcode upport the replication of Oracle database sequence values in a bi-directional configuration. The database sequences must generate values on the target database independent to the source. Therefore, to ensure that the source and target database sequence numbers are unique across the environment, it is best practice to assign odd and even values to each.

. [ 114 ].
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