Question

I am using a PL/SQL procedure to extract Oracle tables of a particular schema to csv format. I execute the procedure by the following command:

exec dump_table_to_csv ( 'schema.tablename',  'directory',  'tablename.csv');

The directory is created using the following command:

CREATE DIRECTORY <directory_name> AS '<operating_system_path>';

The PL?SQL procedure code is as follows:

create or replace procedure dump_table_to_csv( p_tname in varchar2,
                                                   p_dir   in varchar2,
                                                   p_filename in varchar2 )
    is
        l_output        utl_file.file_type;
        l_theCursor     integer default dbms_sql.open_cursor;
        l_columnValue   varchar2(4000);
        l_status        integer;
        l_query         varchar2(1000)
                       default 'select * from ' || p_tname;
       l_colCnt        number := 0;
       l_separator     varchar2(1);
       l_descTbl       dbms_sql.desc_tab;
   begin
       l_output := utl_file.fopen( p_dir, p_filename, 'w', 32760);
       execute immediate 'alter session set nls_date_format=''dd-mon-yyyy hh24:mi:ss'' ';

       dbms_sql.parse(  l_theCursor,  l_query, dbms_sql.native );
       dbms_sql.describe_columns( l_theCursor, l_colCnt, l_descTbl );

       for i in 1 .. l_colCnt loop
           utl_file.put( l_output, l_separator || '"' || l_descTbl(i).col_name || '"' );
           dbms_sql.define_column( l_theCursor, i, l_columnValue, 4000 );
           l_separator := ',';
       end loop;
       utl_file.new_line( l_output );

       l_status := dbms_sql.execute(l_theCursor);

       while ( dbms_sql.fetch_rows(l_theCursor) > 0 ) loop
           l_separator := '';
           for i in 1 .. l_colCnt loop
               dbms_sql.column_value( l_theCursor, i, l_columnValue );
               utl_file.put( l_output, l_separator || l_columnValue );
               l_separator := ',';
           end loop;
           utl_file.new_line( l_output );
       end loop;
       dbms_sql.close_cursor(l_theCursor);
       utl_file.fclose( l_output );

       execute immediate 'alter session set nls_date_format=''dd-MON-yy'' ';
   exception
       when others then
           execute immediate 'alter session set nls_date_format=''dd-MON-yy'' ';
           raise;
   end;
   /

However, when the tables increases , this process takes too long. My question is how can I modify the code so that I can process list the schema tables and put it in a file and then the procedure will process all the tables listed in a file? If that way is not fast or possible, what other way can I process the extraction in one run without having to execute the procedure for each table?

Answer 1

what other way can I process the extraction in one run without having to execute the procedure for each table?

You could automate the running of the current procedure as follows:

begin
   for r in (select table_name from all_tables where owner = 'SCHEMA') loop
      dump_table_to_csv 
         ('schema.'||r.table_name, 'directory', r.table_name||'.csv');
   end loop;
end;

Or you could re-write the procedure to be run as:

exec dump_schema_to_csvs ('schema', 'directory')

i.e. put the FOR loop from my first example inside the procedure.

Neither of these can be expected to run any faster than the current method though.