首页 > 数据库 > Oracle > Oracle GoldenGate11.1 DBLOGREADER&DBLOGREADERBUFSIZE 严于律己


Oracle 作者:yangyonglin007 时间:2013-11-08 10:26:59 0 删除 编辑
(Oracle) Causes Extract to use a newer ASM API that is available as of Oracle and later 10g R2 versions,
and Oracle and later 11g R2 versions (but not in Oracle 11g R1 versions).

When used, DBLOGREADER enables Extract to use a read size of up to 4 MB in size. This is controlled with the DBLOGREADERBUFSIZE option

A larger buffer may improve the performance of Extract when redo rate is high.

When using DBLOGREADER, do not use the ASMUSER and ASMPASSWORD options of TRANLOGOPTIONS. The API uses the user and password specified with the USERID parameter.

(Oracle ASM) Controls the maximum size, in bytes, of a read operation into the internal buffer that holds theresults of each read of the transaction log. 
Higher values increase extraction speed but cause Extract to consumemore memory. 
Low values reduce memory usage but increase I/O because Extract must store data that exceeds the cache size to disk.

Use DBLOGREADERBUFSIZE together with the DBLOGREADER option if the source ASM instance is Oracle or later10g R2 versions, or Oracle and later 11g R2 versions (but not Oracle 11g R1 versions).

The newer ASM API in those versions provides better performance than the older one. If the Oracle version is not one of those versions, then ASMBUFSIZE must be used.

The following are the valid ranges and default sizes, in
◆ Minimum: size of one block in the redo log
◆ Maximum: 4 MB
◆ Default: 2 MB (2097152)
The default should be sufficient in most cases.
The value of the BUFSIZE option must always be at least
equal to, or greater than, the value of DBLOGREADERBUFSIZE.

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