Utl_file simultaneous usage

Question

i will use a stored procedure for db-logging in a file using utl_file (fopen/put_line/fflush/fclose)
- may i have problems with simultaneous calls to this procedure within different sessions or i must use some kind of locking ?

Answer 1

user605483 wrote:
i will use a stored procedure for db-logging in a file using utl_file (fopen/put_line/fflush/fclose)
- may i have problems with simultaneous calls to this procedure within different sessions or i must use some kind of locking ?Yes - but if you use text and "+write append+" to the file, your code is fairly thread safe.
The problem is with the file pointer in session A versus session B. Session B writes to the file. This does not advance the file pointer in session A. Thus when session A writes to the file, it overwrites the data just written by session B.
A write append automatically writes the data at the end of the file (the file pointer is moved to eof and the write happens). Write append is only valid for text files - not binary files (though you can likely simulate it, but it would not make much sense).
As writes to the same file is serialised (due to the file being opened in shared mode), there's no problem in both sessions doing a write append at the same time. (except for the performance issue of serialisation)
But the concept of writing log files from an Oracle RDBMS - that is just plain horrible. This is not the 80's anymore (despite us missing the music and hairstyles) and Oracle is not Cobol writing to ISAM files.
The correct place for logs is inside a plain Oracle SQL table - that can be indexed, partitioned. That can be read and filtered using SQL. That implements concurrency controls. That has Oracle security features. Forms part of the database backup strategy. Etc.
IMO there is no valid reason for storing PL/SQL processing logs externally. (a debate I've often had in the past with developers and one I have yet to lose)