"Frank Millman" wrote in message news:n8038j$575$1...@ger.gmane.org...
I am developing a typical accounting/business application which involves a
front-end allowing clients to access the system, a back-end connecting to
a database, and a middle layer that glues it all together.
[...]
There was one aspect that I deliberately ignored at that stage. I did not
change the database access to an asyncio approach, so all reading
from/writing to the database involved a blocking operation. I am now ready
to tackle that.
I am making some progress, but I have found a snag - possibly unavoidable,
but worth a mention.
Usually when I retrieve rows from a database I iterate over the cursor -
def get_rows(sql, params):
cur.execute(sql, params)
for row in cur:
yield row
If I create a Future to run get_rows(), I have to 'return' the result so
that the caller can access it by calling future.result().
If I return the cursor, I can iterate over it, but isn't this a blocking
operation? As far as I know, the DB adaptor will only actually retrieve the
row when requested.
If I am right, I should call fetchall() while inside get_rows(), and return
all the rows as a list.
This seems to be swapping one bit of asynchronicity for another.
Does this sound right?
Frank
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