Re: indexes and big tables

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От Robert Vojta
Тема Re: indexes and big tables
Дата
Msg-id 20010727150226.N6382@ipex.cz
обсуждение исходный текст
Ответ на indexes and big tables  (Robert Vojta <vojta@ipex.cz>)
Список pgsql-hackers
> The index is only used for the line= part of the where clause
> with your query. With many rows the "line=" is not selective enough
> to justify the index.
 I tried move only needed data into new table and change query into ...

netacc=> EXPLAIN SELECT counterfrom AS from, counterto AS to,
floor((980000000 - date_part('epoch', counterstamp)) / 300) AS sequence
FROM graphs_5m WHERE line='absolonll'; NOTICE:  QUERY PLAN:
Index Scan using graphs_5m_idx on graphs_5m (cost=0.00..58.38 rows=29
width=24)
EXPLAIN
 and query runs for 3-5 seconds. Any idea how to make it faster? I think,
that now it's ready to HW upgrade for faster result ...

Best regards, Robert

--   _ |-|  __      Robert Vojta <vojta-at-ipex.cz>          -= Oo.oO =- |=| [Ll]     IPEX, s.r.o. "^" ====`o

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