Re: Large Database Design Help

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От Markus Schaber
Тема Re: Large Database Design Help
Дата
Msg-id 43EC6531.60202@logix-tt.com
обсуждение исходный текст
Ответ на Re: Large Database Design Help  (Greg Stark <gsstark@mit.edu>)
Список pgsql-performance
Hi, Greg,

Greg Stark wrote:

>>    (Aside question: if I were to find a way to use COPY and I were loading
>>data on a single client_id, would dropping just the indexes for that client_id
>>accelerate the load?)
> Dropping indexes would accelerate the load but unless you're loading a large
> number of records relative the current size I'm not sure it would be a win
> since you would then have to rebuild the index for the entire segment.

And, additionally, rebuilding a partial index with "WHERE client_id=42"
needs a full table scan, which is very slow, so temporarily dropping the
indices will not be useful if you merge the tables.

Btw, I don't know whether PostgreSQL can make use of partial indices
when building other partial indices. If yes, you could temporarily drop
all but one of the partial indices for a specific client.


HTH,
Markus

--
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org

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