nice :) how it's "rewrite"?
2015-10-02 22:25 GMT-03:00 Justin Swanhart <[email protected]>: > Hi, > > You could use Shard-Query. You don't need to shard the database, you can > point shard-query at one database. It supports WINDOW functions. > > select > date, > FIRST_VALUE(value) OVER (ORDER BY value ASC), > LAST_VALUE(value) OVER (ORDER BY value ASC) > FROM some_table AS a > GROUP BY date > > --Justin > > On Fri, Oct 2, 2015 at 6:12 PM, Roberto Spadim <[email protected]> > wrote: > >> Hi guys >> I have a problem and a possible solution, that i think is relative easy >> to develop (i didn't tested but i think the source is easy to change) >> >> i have some queries like: >> >> >> SELECT >> date, >> (SELECT value FROM some_table WHERE date=a.date ORDER BY date ASC LIMIT >> 1) AS first, >> (SELECT value FROM some_table WHERE date=a.date ORDER BY date DESC LIMIT >> 1) AS last >> FROM some_table AS a >> GROUP BY date >> >> >> i want to "convert" the complex sub query, to a agregate function, and i >> thinking about group concat: >> from mysql docs: >> >> GROUP_CONCAT([DISTINCT] *expr* [,*expr* ...] >> [ORDER BY {*unsigned_integer* | *col_name* | *expr*} >> [ASC | DESC] [,*col_name* ...]] >> [SEPARATOR *str_val*]) >> >> >> we have ORDER BY >> if we could include a "LIMIT" clause, i could rewrite this query to: >> >> SELECT >> date, >> GROUP_CONCAT(value ORDER BY date ASC LIMIT 1) AS first, >> GROUP_CONCAT(value ORDER BY date DESC LIMIT 1) AS last >> FROM some_table AS a >> GROUP BY date >> >> >> i know that i could have stats tables / materialized views (with >> flexview, i already tested :) ), but i want something more "easy to use" >> and not "very fast", just a "feature" to solve small problems >> >> >> it's a nice idea? does anyone have this "problem" and solve with other >> solutions? >> >> -- >> Roberto Spadim >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~maria-discuss >> Post to : [email protected] >> Unsubscribe : https://launchpad.net/~maria-discuss >> More help : https://help.launchpad.net/ListHelp >> >> > -- Roberto Spadim SPAEmpresarial - Software ERP Eng. Automação e Controle
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