Shulou(Shulou.com)06/01 Report--

I. introduction to GoldenGate

OGG is a log-based structured data replication software.

OGG can realize the real-time capture, transformation and delivery of a large number of transaction data, synchronize the data between the source database and the target database, and maintain the minimum data delay of 10ms.

two。 working principle

three。 Related components

1.Manager

Responsible for the overall monitoring and management of OGG

(1) Generation and deletion of .Trail files

(2)。 Monitor the process regularly and be responsible for the start / stop of the process

2.Extract (Capture)

(1)。 Get the DB change information from redo or archive log and get the value before and after the change of the primary key or unique key

(2)。 Read the REDO log at regular intervals to get change information

Parameter EOFDELAY or EOFDELAYCSECS setting. Default 1s, minimum 10ms

(3)。 Export to a local or remote Trail file when the following conditions are met

-Extract's buffer is full

-set the parameter FLUSHSECS or FLUSHCSECS to specify the interval. Default 1s, minimum 10ms

3.Extract (Pump)

Send the local Trail queue to the destination Collector

The sending interval meets any of the following conditions:

(1)。 When the cache is full

The RMHOST parameter of Pump (TCPBUFSIZE option), which can specify the cache size. Default 30000bytes

(2)。 Parameter assignment

FLUSHSECS or FLUSHCSECS. Default 1s, minimum 10ms

4.Collector

Send from Extract pump to Collector and output to Trail file

5.Replicat

The SQL statement generated from the Trail file is executed in the target DB.

four。 Initial data synchronization

1. Make use of database function

RMAN,expdp/impdp

two。 Take advantage of OGG function

Sets the capture and replication process for initialization properties. It is recommended to use small databases.

five。 Limit

1. Unsupported data types

ANYDATA,BFILE,TIMEZONE_ABBR,URITYPE,ANYDATASET,BINARY_INTEGER,TIMEZONE_REGION,UROWID,ANYTYPE,MLSLABEL,PLS_INTEGER

Objects not supported by 2.DML

Compressed tables, external tables, REF, aliases, DML that does not output logs

3. Unsupported DDL

DDL for system tables / system views

Use Recycle Bin

4. Unsupported object name

The following characters and Chinese are not available for object names:

& *? :; Space

5. Character set

The character set of the destination DB must be a superset of the source DB character set

6. Other

(1). Sequence cannot be used in two-way replication of sequence. When cache of sequence is used in one direction, the source and destination are out of sync.

(2) the target DB needs to delete the Trigger.

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