Re: Index Not being used.
Posted by: Rick James ()
Date: June 04, 2016 05:14PM
SELECT l.ORD_Item, l.ORD_Desc, l.ORD_Item_Class, SUM(l.ORD_Qty), SUM(ROUND(l.ORD_Qty * l.ORD_Price, 2)) FROM pos_ord_headers AS h JOIN pos_ord_lines AS l ON l.ORD_ID = h.ORD_ID WHERE h.ORD_Date>='2015-01-01' AND h.ORD_DATE <'2015-01-01' + INTERVAL 1 YEAR; headers: INDEX(ORD_DATE, ORD_ID) -- 'covering index' is much smaller and faster
Changing to InnoDB would speed things up, too. This is because of the PRIMARY KEY(ORD_ID, ...) being 'clustered'. Caveat: Changing to InnoDB would double or triple the disk footprint of the tables. See http://mysql.rjweb.org/doc.php/myisam2innodb for notes on conversion.
You have an accuracy issue... FLOAT can contain only 6-7 significant digits. If you had the monetary value of 987654.32, the 0.32 would be messed up. Also, FLOAT incurs an extra rounding when reading and writing; this can lead to other errors. Recommend DECIMAL instead of FLOAT. (Note: FLOAT occupies 4 bytes; DECIMAL(15,4) takes 7; DECIMAL(9,4) takes 5.)
Another solution is to build "summary tables". You could summarize each day (or week or month) into another table, then do this 'report' from that table. The speedup might be 10x. More discussion: http://mysql.rjweb.org/doc.php/summarytables
|Index Not being used.||617||Greg Mundt||05/26/2016 02:29PM|
|Re: Index Not being used.||324||Peter Brawley||05/26/2016 03:53PM|
|Re: Index Not being used.||340||Øystein Grøvlen||05/27/2016 12:45AM|
|Re: Index Not being used.||307||Greg Mundt||05/27/2016 07:05AM|
|Re: Index Not being used.||307||Rick James||05/27/2016 11:29PM|
|Re: Index Not being used.||305||Greg Mundt||05/31/2016 07:04AM|
|Re: Index Not being used.||301||Rick James||05/31/2016 09:26PM|
|Re: Index Not being used.||336||Greg Mundt||06/01/2016 05:40AM|
|Re: Index Not being used.||280||Rick James||06/01/2016 11:29AM|
|Re: Index Not being used.||327||Greg Mundt||06/01/2016 11:41AM|
|Re: Index Not being used.||328||Rick James||06/04/2016 05:14PM|
|Re: Index Not being used.||333||Greg Mundt||05/27/2016 10:14AM|
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