Does external table creation creates REDO log ?

[cheguvera]

Hi all,

I am on Oracle 10.1 on Solaris, but my question is generic.

I am creating an external table from a CSV text file. In the process of creating and reading (using) this external table any REDO information will be generated?

Till 8i, for loading CSV files, I would load the file with SQL*loader to a staging table and then process the data. This process of loading to staging table will create redo log information (unless I use NOLOGGING, which I cannot use for some reason).
Since 9i and 10g, I can create external table of the CSV file and use it. What can be the internal working of external table? Does it load the data to some temporary table internally (transparant to us)? or does Oracle reads the external source file as it needs it?

Important question is, in the whole affair of using a read-only external table, will Oracle create redo log information?

Please help.

Regards

 

[carp]

Since external tables are in effect "read only", no DML is possible on an external table. Since you are not doing any DML, there will be no REDO generated.

In the past, when you were sql*loading your CSV into a staging table, you were doing INSERTs on the staging table; hence, redo was generated. This does not happen with external tables.