Re: Understanding EXPLAIN ANALYZE output - Mailing list pgsql-general

From Ed L.
Subject Re: Understanding EXPLAIN ANALYZE output
Date
Msg-id 200502091538.32870.pgsql@bluepolka.net
Whole thread Raw
In response to Re: Understanding EXPLAIN ANALYZE output  (Martijn van Oosterhout <kleptog@svana.org>)
Responses Re: Understanding EXPLAIN ANALYZE output  (Martijn van Oosterhout <kleptog@svana.org>)
Re: Understanding EXPLAIN ANALYZE output  ("Ed L." <pgsql@bluepolka.net>)
List pgsql-general
On Wednesday February 9 2005 3:13, Martijn van Oosterhout wrote:
>
> In general, the EXPLAIN ANALYZE output follows the planner
> output as close as possible. If you look at the original query
> posted, it showed an Index Scan costing 4.63..4.63 which means
> the index scan is taking (on average) 4.63ms to return 1 row!
> If it displayed as 4000 or something it would be a lot less
> clear what was going on.
>
> Hope this helps,

Both replies help very much, thanks.  Regarding 4.63ms to return
a row, I know I/O speeds vary widely depending on conditions and
hardware, but what would you say is a "red flag" value for the
actual time to retrieve a row.  I see that for most of the other
times in this example, 0.01ms to 0.10ms is not unusual.

Ed


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