Re: SQL challenge--top 10 for each key value?
От | elein |
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Тема | Re: SQL challenge--top 10 for each key value? |
Дата | |
Msg-id | 20040411112042.B9217@cookie.varlena.com обсуждение исходный текст |
Ответ на | Re: SQL challenge--top 10 for each key value? (Greg Stark <gsstark@mit.edu>) |
Список | pgsql-sql |
No, it will not work twice in the same query as is. If you want to code two counter buckets and pass in some way to distinguish between the two yada yada yada it is possible. It is also possible to code this to do multi-level counting/breaks/calculations, etc. But the SD dictionary is by connection. So any values stored in it need to be initialized at the appropriate time *outside* of the first use. elein On Sun, Apr 11, 2004 at 12:38:20AM -0400, Greg Stark wrote: > > elein <elein@varlena.com> writes: > > > create or replace function pycounter(integer) > > returns integer as > > ' > > if args[0] == 0: > > SD["nextno"] = 1 > > return SD["nextno"] > > try: > > SD["nextno"] += 1 > > except: > > SD["nextno"] = 1 > > return SD["nextno"] > > ' language 'plpythonu'; > > > > And clearly it can be done faster as a little > > C function. > > Does this approach have a hope of working if it's used twice in the same > query? > > > -- > greg > > > ---------------------------(end of broadcast)--------------------------- > TIP 9: the planner will ignore your desire to choose an index scan if your > joining column's datatypes do not match
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