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I would like to query my SimpleDB domain to get the count of records that match a certain criteria. Something that could be done like this:

rs = appsDomain.select("SELECT count(*) FROM %s WHERE (%s='%s' or %s='%s') and %s!='%s'" % (APPS_SDBDOMAIN, XML_APPNODE_NAME_ATTR, appName, XML_APPNODE_RESERVED_NAME_ATTR, appName, XML_EMAIL_NODE, thisSession.email), None, True)

After doing some reading I have found that possibly getting a query count from SimpleDB via the SDBManager count method might be more efficient than doing a straight forward "count(*)" style query. Further, I would love not to have to loop over a result set when I know there is only one row and column that I need yet I would want to avoid this too:

count = int(rs.iter().next()['Count'])

Is it true that SDBManager is more efficient? Is there a better way? If SDBManager is the best way can anyone show me how to use it as I have been thoroughly unsuccessful?

Thanks in advance!

Jason Leidigh
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1 Answers1

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Well, I stopped being lazy and simply went to the source to get my answer (FROM: boto-2.6.0-py2.7.egg/boto/sdb/db/manager/sdbmanager.py)

def count(self, cls, filters, quick=True, sort_by=None, select=None):
"""
Get the number of results that would
be returned in this query
"""
query = "select count(*) from `%s` %s" % (self.domain.name, self._build_filter_part(cls, filters, sort_by, select))
count = 0
for row in self.domain.select(query):
    count += int(row['Count'])
    if quick:
        return count
return count

As you can see the sdbmanager.count method does nothing special and in fact does what I was hoping to avoid which is looping over a record store just to get the 'Count' value(s).

So in the end I will probably just implement this method myself as using the SDBManager actually implies a lot more over head which, in my case, is not worth it.

Thanks!

Jason Leidigh
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