ДокументацияThe optional maxlen argument truncates the converted expression string to the specified number of characters when indexing or collating. For example, if you insert a long string with maxlen truncation, the full string is inserted and can be retrieved by a SELECT statement; the index global for this string is truncated to the specified length. This means that ORDER BY and comparison operations only evaluate the truncated index string. Such truncation is especially useful for indexing on strings that exceed the 255-character limit for Caché subscripts. When converting from non-Caché systems, some users encountered problems when they indexed on a VARCHAR(255) field and then tried to insert data into the table. With the maxlen argument, if you need to index on a long field, you can use the truncation length parameter.
источник Вариант решенияIndex idxs On s As SQLUPPER(100);
Property s As %VarString;

kolesov ,

Для индексации "неограниченных" строк, а заодно и ускорения поиска, сто́ит попробовать iFind : 15885843 (и далее 15886647 , 15887128 )