conn = psycopg2.connect(database="tax_analytical", user="postgres", password="xxxx", host='xxxx')
cur = conn.cursor('nodes_database')
SQL = ("SELECT Distinct On (
nodes.id) nodes.ID from nodes inner join income on substring(
nodes.name from E'\\w.*\\s(\\w.*)$|\\w+\\s(\\w.*)$') = substring(
income.name from E'\\w.*\\s(\\w.*)$|\\w+\\s(\\w.*)$') limit 1000")
cur.execute(SQL)
if __name__ == '__main__':
pool = multiprocessing.Pool(processes=5)
pool.map(network_file.main, cur, 1) # Ensure the chunk size is 1
pool.close()
pool.join()
cur.close()
conn.close()
-Håvard Wahl Kongsgård
On Mon, Jun 6, 2011 at 8:58 AM, Federico Di Gregorio
<federico.digregorio@dndg.it> wrote:
On 06/06/11 08:32, Håvard Wahl Kongsgård wrote:
> Hi, with psycopg 2-2.4.1 I have some issue with incorrect use of indexes
> using regular expression.
> I my case I have create on index on the surname of users.
> CREATE INDEX income_surname ON income(substring(
income.name
>
> then used
> SELECT Distinct On (nodes.id <http://nodes.id>) nodes.ID from nodes
> inner join income on substring(nodes.name <http://nodes.name> from
> E'\\w.*\\s(\\w.*)$|\\w+\\s(\\w.*)$') = substring(
income.name
>
> with psql the index works fine, but with psycopg I don't think it's used
> at all. The index substring has to be identical with the substring in
> the query. Are there some encoding issues with psycopg?
psycopg does encode your strings to the backend encoding but this
shouldn't be a problem. You can:
1) Send us the code so we can analyze it.
2) Enable PostgreSQL query logging and check the query sent by psycopg.
3) I feel you're doing something wrong with the '\' in the regular
expression. Can you should us the Python of the execute() call?
federico
--
Federico Di Gregorio federico.digregorio@dndg.it
Studio Associato Di Nunzio e Di Gregorio http://dndg.it
There's no certainty - only opportunity. -- V
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