translation performance dramatic improvement

Drupal 4.6.5: There is a problem with performance while translation is being used. The database query (for instance):

SELECT s.lid, t.translation FROM locales_source s INNER JOIN locales_target t ON s.lid = t.lid WHERE s.source = 'this is purely fictious English text example' AND t.locale = 'pl'

takes (for instance) 100 time units to execute. The problem is: there is no index on 'source' field. After:

ALTER TABLE `locales_source` ADD INDEX `source` ( `source` ( 15 ) );

i.e. creating additional index on (for example) 15 first chars of English string, the database query takes 1 (yes: one!) time unit to execute. The performance improvement is therefore dramatic, especially while many strings to translate are present on the page.

This is a suggestion for developers: please add creation of the abovementioned index to the distribution.

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mhg