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Asked: 2026-05-13T08:33:35+00:00

I have a MySQL table with 3 fields: Location Variable Value I frequently use

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I have a MySQL table with 3 fields:

  • Location
  • Variable
  • Value

I frequently use the following query: 

SELECT * 
  FROM Table 
 WHERE Location = '$Location' 
   AND Variable = '$Variable' 
ORDER BY Location, Variable

I have over a million rows in my table and queries are somewhat slow. Would it increase query speed if I added a field VariableLocation, which is the Variable and the Location combined? I would be able to change the query to:

SELECT * 
  FROM Table 
 WHERE VariableLocation = '$Location$Variable' 
ORDER BY VariableLocation
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1 Answer

  1. Editorial Team

    Correction Update:

    Courtesy: @paxdiablo:

    A column in the table will make no difference. All you need is an index over both columns and the MySQL engine will use that. Adding a column in the table is actually worse than that since it breaks 3NF and wastes space. See http://dev.mysql.com/doc/refman/5.0/en/mysql-indexes.html which states: SELECT * FROM tbl_name WHERE col1=val1 AND col2=val2; If a multiple-column index exists on col1 and col2, the appropriate rows can be fetched directly.

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