Hi,
I am using sqlalchemy version 0.7.6 on Win 7. I am using sqlalchemy to
execute raw SQL queries in parallel. Here is how I do it:
eng = get_engine() #Threadsafe method to get engine
raw_con = eng.connect().connection.connection
raw_con.autocommit= True
crsr = raw_con.cursor()
res = crsr.execute (qry, *multiparams) #multiparams is empty in my case
raw_con.autocommit= False
If it is a select query:
res_fetched = res.fetchall()
res.close()
Sometimes, I get *Error: ('HY000', '[HY000] [Microsoft][ODBC SQL Server
Driver]Connection is busy with results for another hstmt (0)
(SQLExecDirectW)')*
Looking at the logs I can see that two queries were indeed running
together- one was a bulk insert (an update query) and another was a select
query.
If it is a select query:
res_fetched = res.fetchall()
is just a convenient\brief way of writing it here. I actually have separate
select and update functions, that call the 'execute' function. The select
function will then do a fetchall, but the update function will not.
>From the docs
>here<http://docs.sqlalchemy.org/en/rel_0_7/core/connections.html#sqlalchemy.engine.base.Engine.connect>
:
The
Connection<http://docs.sqlalchemy.org/en/rel_0_7/core/connections.html#sqlalchemy.engine.base.Connection>
object
is a facade that uses a DBAPI connection internally in order to communicate
with the database. This connection is procured from the connection-holding
Pool<http://docs.sqlalchemy.org/en/rel_0_7/core/pooling.html#sqlalchemy.pool.Pool>
referenced
by this
Engine<http://docs.sqlalchemy.org/en/rel_0_7/core/connections.html#sqlalchemy.engine.base.Engine>.
When the
close()<http://docs.sqlalchemy.org/en/rel_0_7/core/connections.html#sqlalchemy.engine.base.Connection.close>
method
of the
Connection<http://docs.sqlalchemy.org/en/rel_0_7/core/connections.html#sqlalchemy.engine.base.Connection>
object
is called, the underlying DBAPI connection is then returned to the
connection pool, where it may be used again in a subsequent call to
connect()<http://docs.sqlalchemy.org/en/rel_0_7/core/connections.html#sqlalchemy.engine.base.Engine.connect>
.
If I understand the above correctly, and assuming that the engine connect
function is thread safe, the two queries running simultaneously should be
running with different raw_con objects.
Not sure why I am running into this error.
Thanks!
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