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Oracle Export Parameters-Buffer
链接：http://www.eygle.com/digest/2008/01/oracle_export_parametersbuffer.htmlExport Parameters
This section contains descriptions of the Export command-line parameters.
BUFFER
Default: operating system-dependent. See your Oracle operating system-specific documentation to determine the default value for this parameter.
Specifies the size, in bytes, of the buffer used to fetch rows. As a result, this parameter determines the maximum number of rows in an array fetched by Export. Use the following formula to calculate the buffer size:
buffer_size = rows_in_array * maximum_row_size
If you specify zero, the Export utility fetches only one row at a time.
Tables with columns of type LOBs, LONG, BFILE, REF, ROWID, LOGICAL ROWID, or DATE are fetched one row at a time.
Note:
The BUFFER parameter applies only to conventional path Export. It has no effect on a direct path Export. For direct path Exports, use the RECORDLENGTH parameter to specify the size of the buffer that Export uses for writing to the export file.
Example: Calculating Buffer Size
This section shows an example of how to calculate buffer size.
The following table is created:
CREATE TABLE sample (name varchar(30), weight number);
The maximum size of the name column is 30, plus 2 bytes for the indicator. The maximum size of the weight column is 22 (the size of the internal representation for Oracle numbers), plus 2 bytes for the indicator.
Therefore, the maximum row size is 56 (30+2+22+2).
To perform array operations for 100 rows, a buffer size of 5600 should be specified.
By eygle on 2008-01-27 13:09 | Comments (0) | Posted to Oracle摘 |Pageviews:
