You said:
--------------------------
is there a way to calculate the number of rows retrieved by a mysql query,
without actually performing it?
I want to make a paginated result like in most search engines, and for that
I need to display the number of pages
the result would have, but I do not want to actually retrieve all the rows
to be able to count them, because this is
a loss of performance, in particular if the result set retrieves 100000
rows
and 100 people make a search; this would
end in 10000 x 100 rows just to say how many pages the result will have, I
think there must be a better way to do it, isn't it?
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If you add SQL_CALC_FOUND_ROWS to the SELECT statement with LIMIT (as
explained at
http://www.mysql.com/doc/S/E/SELECT.html )
you can then use the FOUND_ROWS() function described at
http://www.mysql.com/doc/M/i/Miscellaneous_functions.html
to return the numer of rows that would have been returned without a LIMIT
statement.
This statement is only available from MySQL 4.0, and presumably depends for
its performance on the V4 query cacheing (I.e. as you repeatedly re-query
with different LIMITs, it doen't redo the select because it recognises a
familar request).
Alec Cawley
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