fastest way to count - check for mere existence of any record

[Alex Glaros]

Anyone have syntax to optimize speed of count, to check record existance?

Often just want to check for the existence of ANY records and don't need a full count, but I only know how to get info from full count.  See below where logic only cares if count is greater than zero.

    checking_for_already_existing_connection_count = db((db.VerifiedConnection.personID == personID.id) & (db.VerifiedConnection.connectedTo == auth.user_id)).count()

    if checking_for_already_existing_connection_count > 0:

        redirect(URL('error_duplicate_role'))

Do you have phrasing that perhaps includes ".select(limitby=(0,1)).first()"?

thanks,

Alex Glaros

[Alex Glaros]

am looking for something like below

    if count(db((db.VerifiedConnection.personID == personID.id) & (db.VerifiedConnection.connectedTo == auth.user_id)).select(limitby=(0,1)).first()) > 0:
        redirect(URL('error_duplicate_role'))

[Massimo Di Pierro]

How about just fetching the id?

if count(db((db.VerifiedConnection.personID == personID.id) & (db.VerifiedConnection.connectedTo == auth.user_id)).select(db.VerifiedConnection.id,limitby=(0,1)).first()) > 0:

[Alex Glaros]

not sure how to structure that syntax Massimo...would this be okay?

    if (db((db.VerifiedConnection.personID == personID.id) & (db.VerifiedConnection.connectedTo == auth.user_id)).select(limitby=(0,1)).first()):

        redirect(URL('error_duplicate_role'))

[Alex Glaros]

oops, meant this

if (db((db.VerifiedConnection.personID == personID.id) & (db.VerifiedConnection.connectedTo == auth.user_id)).select(db.VerifiedConnection.id, limitby=(0,1)).first()):

[Niphlod]

by any chance, is isempty() being totally forgotten ? it just does

return not self.select(limitby=(0,1), orderby_on_limitby=False)

[Alex Glaros]

does this look okay?

if not (db((db.VerifiedConnection.personID == personID.id) & (db.VerifiedConnection.connectedTo == auth.user_id))).isempty():

[Niphlod]

yep.

db(query).isempty() returns True if no records are found, in the uttermost simplicistic and speed-aware method I know, that is basically

db(query).select(limitby=(0,1), orderby_on_limitby=False)

[Alex Glaros]

thanks Niphlod and Massimo

works great

Alex

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