Exporting a CLOB to a text file using Oracle SQL Developer

Question

I am using Oracle SQL Developer and trying to export a table to a CSV file. Some of the fields are CLOB fields, and in many cases the entries are truncated when the export happens. I'm looking for a way to get the whole thing out, as my end goal is to not use Oracle here (I received an Oracle dump - which was loaded into an oracle db, but am using the data in another format so going via CSV as an intermediary).

If there are multiple solutions to this, given that it is a one time procedure for me, I don't mind the more hack-ish type solutions to more involved "do it right" solutions.

Answer 1

if you have access to the file system on your database box you could do something like this:

CREATE OR REPLACE DIRECTORY documents AS 'C:\';
SET SERVEROUTPUT ON
DECLARE
  l_file    UTL_FILE.FILE_TYPE;
  l_clob    CLOB;
  l_buffer  VARCHAR2(32767);
  l_amount  BINARY_INTEGER := 32767;
  l_pos     INTEGER := 1;
BEGIN
  SELECT col1
  INTO   l_clob
  FROM   tab1
  WHERE  rownum = 1;

  l_file := UTL_FILE.fopen('DOCUMENTS', 'Sample2.txt', 'w', 32767);

  LOOP
    DBMS_LOB.read (l_clob, l_amount, l_pos, l_buffer);
    UTL_FILE.put(l_file, l_buffer);
    l_pos := l_pos + l_amount;
  END LOOP;
EXCEPTION
  WHEN OTHERS THEN
    DBMS_OUTPUT.put_line(SQLERRM);
    UTL_FILE.fclose(l_file);
END;
/

Which I copied and pasted from this site.

You may also find this previous question about UTL_FILE useful. It addresses exporting to CSV. I have no idea or experience with how UTL_FILE handles CLOBs, however.

Answer 2

You can use a Python script to take care of the export, the CLOBs won't get truncated:

from __future__ import print_function
from __future__ import division

import time
import cx_Oracle

def get_cursor():
    '''
    Get a cursor to the database
    '''
    # https://stackoverflow.com/questions/24149138/cx-oracle-doesnt-connect-when-using-sid-instead-of-service-name-on-connection-s
    # http://www.oracle.com/technetwork/articles/dsl/prez-python-queries-101587.html
    ip = '' # E.g. '127.0.0.1'
    port = '' # e.g. '3306'
    sid = ''
    dsnStr = cx_Oracle.makedsn(ip, port, sid)
    username = '' # E.g. 'FRANCK'
    password = '' # E.g. '123456'
    db = cx_Oracle.connect(user=username, password=password, dsn=dsnStr)    
    cursor = db.cursor()
    return cursor

def read_sql(filename):
    '''
    Read an SQL file and return it as a string
    '''
    file = open(filename, 'r')
    return ' '.join(file.readlines()).replace(';', '')

def execute_sql_file(filename, cursor, verbose = False, display_query = False):
    '''
    Execute an SQL file and return the results
    '''
    sql = read_sql(filename)
    if display_query: print(sql)
    start = time.time()
    if verbose: print('SQL query started... ', end='')
    cursor.execute(sql)
    if verbose: 
        end = time.time()
        print('SQL query done. (took {0} seconds)'.format(end - start))
    return cursor


def main():
    '''
    This is the main function
    '''
    # Demo:
    cursor = get_cursor()
    sql_filename = 'your_query.sql' # Write your query there
    cursor = execute_sql_file(sql_filename, cursor, True)    
    result_filename = 'result.csv'   # Will export your query result there
    result_file = open(result_filename, 'w')
    delimiter = ','    
    for row in cursor:
        for count, column in enumerate(row):
            if count > 0: result_file.write(delimiter)
            result_file.write(str(column))
        result_file.write('\n')
    result_file.close()


if __name__ == "__main__":
    main()
    #cProfile.run('main()') # if you want to do some profiling

FYI: Help installing cx_Oracle

Answer 3

assuming by an Oracle dump you meant a .dmp (either from export or expdp), you're looking at a binary file. You'll need to import the dumpfile into an Oracle database and then export the data to plain text using UTL_FILE or other means.

Answer 4

Here is a short yet general python script that does just this - dumping tables (with CLOB fields, among the rest) to a flat csv file: OraDump

Answer 5

As Oracle SQL Developer is explicitly mentioned and "hack-ish type solutions" were encouraged (and in case somebody is still in need…):

If a single statement is executed from a SQL Worksheet (in Oracle SQL Developer), the result is displayed as a table. After clicking the result table, use either keyboard shortcuts or the Edit menu to first mark the whole table and then to copy its content. Proceed to your text editor of choice. Paste. Save to a file. Hopefully done. ;-)

Works even for CLOBs exceeding 4000 characters. Whether or not it actually helps, will very much depend on the CLOBs' actual content. Sometimes some SQL pre-processing might get you there…

Alternatively try in the result table's local menu Export…. Going from there through the Excel 95-2003 format option might work (better than CSV or text/TSV).

Please comment, if and as this requires adjustment / further detail.