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178 lines
4.7 KiB
Python
178 lines
4.7 KiB
Python
# copy_from.py -- example about copy_from
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#
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# Copyright (C) 2002 Tom Jenkins <tjenkins@devis.com>
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# Copyright (C) 2005 Federico Di Gregorio <fog@initd.org>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by the
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# Free Software Foundation; either version 2, or (at your option) any later
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# version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY
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# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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# for more details.
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## put in DSN your DSN string
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DSN = 'dbname=test'
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## don't modify anything below this line (except for experimenting)
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import sys
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import os
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import StringIO
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import psycopg2
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if len(sys.argv) > 1:
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DSN = sys.argv[1]
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print "Opening connection using dsn:", DSN
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conn = psycopg2.connect(DSN)
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print "Encoding for this connection is", conn.encoding
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curs = conn.cursor()
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try:
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curs.execute("CREATE TABLE test_copy (fld1 text, fld2 text, fld3 int4)")
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except:
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conn.rollback()
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curs.execute("DROP TABLE test_copy")
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curs.execute("CREATE TABLE test_copy (fld1 text, fld2 text, fld3 int4)")
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conn.commit()
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# copy_from with default arguments, from open file
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io = open('copy_from.txt', 'wr')
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data = ['Tom\tJenkins\t37\n',
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'Madonna\t\\N\t45\n',
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'Federico\tDi Gregorio\t\\N\n']
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io.writelines(data)
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io.close()
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io = open('copy_from.txt', 'r')
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curs.copy_from(io, 'test_copy')
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print "1) Copy %d records from file object " % len(data) + \
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"using defaults (sep: \\t and null = \\N)"
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io.close()
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curs.execute("SELECT * FROM test_copy")
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rows = curs.fetchall()
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print " Select returned %d rows" % len(rows)
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for r in rows:
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print " %s %s\t%s" % (r[0], r[1], r[2])
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curs.execute("delete from test_copy")
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conn.commit()
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# copy_from using custom separator, from open file
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io = open('copy_from.txt', 'wr')
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data = ['Tom:Jenkins:37\n',
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'Madonna:\N:45\n',
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'Federico:Di Gregorio:\N\n']
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io.writelines(data)
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io.close()
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io = open('copy_from.txt', 'r')
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curs.copy_from(io, 'test_copy', ':')
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print "2) Copy %d records from file object using sep = :" % len(data)
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io.close()
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curs.execute("SELECT * FROM test_copy")
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rows = curs.fetchall()
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print " Select returned %d rows" % len(rows)
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for r in rows:
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print " %s %s\t%s" % (r[0], r[1], r[2])
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curs.execute("delete from test_copy")
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conn.commit()
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# copy_from using custom null identifier, from open file
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io = open('copy_from.txt', 'wr')
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data = ['Tom\tJenkins\t37\n',
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'Madonna\tNULL\t45\n',
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'Federico\tDi Gregorio\tNULL\n']
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io.writelines(data)
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io.close()
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io = open('copy_from.txt', 'r')
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curs.copy_from(io, 'test_copy', null='NULL')
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print "3) Copy %d records from file object using null = NULL" % len(data)
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io.close()
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curs.execute("SELECT * FROM test_copy")
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rows = curs.fetchall()
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print " Select using cursor returned %d rows" % len(rows)
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for r in rows:
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print " %s %s\t%s" % (r[0], r[1], r[2])
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curs.execute("delete from test_copy")
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conn.commit()
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# copy_from using custom separator and null identifier
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io = open('copy_from.txt', 'wr')
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data = ['Tom:Jenkins:37\n', 'Madonna:NULL:45\n', 'Federico:Di Gregorio:NULL\n']
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io.writelines(data)
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io.close()
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io = open('copy_from.txt', 'r')
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curs.copy_from(io, 'test_copy', ':', 'NULL')
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print "4) Copy %d records from file object " % len(data) + \
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"using sep = : and null = NULL"
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io.close()
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curs.execute("SELECT * FROM test_copy")
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rows = curs.fetchall()
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print " Select using cursor returned %d rows" % len(rows)
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for r in rows:
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print " %s %s\t%s" % (r[0], r[1], r[2])
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curs.execute("delete from test_copy")
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conn.commit()
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# anything can be used as a file if it has .read() and .readline() methods
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data = StringIO.StringIO()
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data.write('\n'.join(['Tom\tJenkins\t37',
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'Madonna\t\N\t45',
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'Federico\tDi Gregorio\t\N']))
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data.seek(0)
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curs.copy_from(data, 'test_copy')
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print "5) Copy 3 records from StringIO object using defaults"
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curs.execute("SELECT * FROM test_copy")
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rows = curs.fetchall()
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print " Select using cursor returned %d rows" % len(rows)
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for r in rows:
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print " %s %s\t%s" % (r[0], r[1], r[2])
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curs.execute("delete from test_copy")
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conn.commit()
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# simple error test
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print "6) About to raise an error"
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data = StringIO.StringIO()
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data.write('\n'.join(['Tom\tJenkins\t37',
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'Madonna\t\N\t45',
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'Federico\tDi Gregorio\taaa']))
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data.seek(0)
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try:
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curs.copy_from(data, 'test_copy')
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except StandardError, err:
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conn.rollback()
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print " Caught error (as expected):\n", err
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conn.rollback()
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curs.execute("DROP TABLE test_copy")
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os.unlink('copy_from.txt')
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conn.commit()
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