GoldenGate New Features: Metadata Encapsulation


imageGoldenGate pre- doesn’t store table structure in trail files and in some cases it was an issue: when we received trail file — we didn’t know source table structure from the file. We had only record and this record contained field values. But we didn’t know field names. So earlier we chose how to manage this. There are two ways:

— assume that source table is the same as target table (ASSUMETARGETDEFS). In this case first value from trail record was written to first field of target table, the second value to the second field, etc. But this method doesn’t work in general case where source and target tables are different

— extract table definitions from source and gave this definition to replicat (SOURCEDEFS). In this case trail files were parsed and applied according to the static source table definition (stored in file). This method gave us flexibility but increased number of manual work: when source table structure changes — we must regenerate DEF-file or we can lose data consistency.

Now we don’t need ASSUMETARGETDEFS and SOURCEDEFS anymore. GoldenGate automatically transfers definitions in trail files. Moreover it retransfer definition when table structure changes (but retransfer will be triggered only after DML on this table) and also retransfer will be done after switch to new trail file (also we should wait for first DML).

There are two special new record types for table definition transfer: DDR (Database Definition Record) and TDR (Table Definition Record). The first one describes database, the second one is for table structure.

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Configuring GoldenGate agent for ODI and Enterprise Manager (version 12.2)

Core GoldenGate is software completely written in C/C++. But many Oracle tools are written using Java. For example, Enterprise Manager and GoldenGate Monitor. ETL tool Oracle Data Integrator was also developed using Java. All these tools work with GoldenGate and communications should be secured: there should be authentication, encryption, etc.

Oracle uses special agent to make these communications possible. We call these agent imageGoldenGate Agent (previously it was called JAgent). If will look at GoldenGate 11.2 or 12.1 then we see this agent is embedded: there are folders cfg and dirjar in GoldenGate Home. First folder contains GoldenGate configuration, the second one contains java libraries (jar) for GoldenGate agent execution.

There were some limitation of embedded agent: you couldn’t create multiple agents (for OEM and GG Monitor), you must remove old agent and add new one to make communications with server (Monitor or OEM) more stable. Oracle has removed GoldenGate Monitor from core GoldenGate 12.2 installation to overcome these limitations. So we should install GoldenGate Agent before configuring communications with OEM and ODI. Unfortunately GoldenGate Agent documentation is a little bit poor. So am writing this article to compensate this issue.

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