a)

SELECT word FROM tablename ORDER BY id ASC
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b)

ALTER TABLE tablename ADD INDEX(line_n);
ALTER TABLE tablename ADD INDEX(word_position);
ALTER TABLE tablename ADD INDEX(line_n,word_position);
SELECT word FROM tablename USE INDEX(line_n,word_position) ORDER BY (l
+ine_n*100+word_position) ASC;
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version b) looks more complicated, but it makes you independent from the identifiers.