Using Postgres 8.3.1
Consider the following script. In SA 0.4.3 it works as intended. In SA
0.4.6, it does not. In particular, the time to get the resultset in 0.4.3
is sub-second. The time in 0.4.6 is about 20 seconds. Also, when running
on 0.4.3 the memory consumption of the script is constant under 10MB. When
running on 0.4.6, it grows to hundreds of MB and is dependent on the size of
the result set. Seems to me that 0.4.3 used a cursor like it was configured
to and 0.4.6 ignored the server_side_cursors=True parameter to the
create_engine call. How do I make 0.4.6 use server side cursors?
#!/usr/bin/python
from time import time
from sqlalchemy import text
from sqlalchemy import create_engine
stime = time()
engine = create_engine('postgres://[EMAIL PROTECTED]/postgres',
server_side_cursors=True, encoding='utf-8')
conn = engine.connect()
trans = conn.begin()
print "have engine, connection, transaction after about %.4f seconds" %
(time() - stime)
stime = time()
rs = conn.execute(text("select * from generate_series(1,1000) s0,
generate_series(1,10000) s1"))
print "have resultset after about %.4f seconds" % (time() - stime)
count = 0
stime = time()
for r in rs:
count += 1
print "counted %s rows after about %.4f seconds" % (count, time() - stime)
stime = time()
rs.close()
print "closed resultset after about %.4f seconds" % (time() - stime)
stime = time()
trans.commit()
print "commited after about %.4f seconds" % (time() - stime)
stime = time()
conn.close()
print "closed connection after about %.4f seconds" % (time() - stime)
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