Avoidance in a multibyte code set

HCL OneDB™ database servers do not allow partial characters to occur. The GLS feature prevents the database server from returning the specified range of bytes literally when this range contains partial characters.

If your database locale supports a multibyte code set and you specify a particular column substring in a query, the database server replaces any truncated multibyte characters with single-byte white space characters.

For example, suppose the multi_col column contains the string A¹A²A³A⁴B¹B²B³B⁴, and you execute the following SELECT statement:

SELECT multi_col FROM tablename WHERE multi_col[2,4] = 'A¹A²B¹B²'

The query returns no rows because the database server converts the substring multi_col[2,4], namely the string A²A³A⁴, to three single-byte blank spaces (sss). The WHERE clause specifies this search condition:

WHERE 'sss' = 'A¹A²A³'

Because this condition is never true, the query retrieves no matching rows.

HCL® OneDB database servers replace partial characters in each individual substring operation, even when they are concatenated.

For example, suppose the multi_col column contains A¹A²B¹B²C¹C²D¹D², and the WHERE clause contains the following condition:

multi_col[2,4] | multi_col[6,8]

The query does not return any rows because the result of the concatenation (A²B¹B²C²D¹D²) contains two partial characters, A² and C². The HCL OneDB database server converts these partial characters to single-byte blank spaces and creates the following WHERE clause condition:

WHERE 'sB¹B²sD¹D²' = 'A¹A²B¹B²'

This condition is also never true, so the query retrieves no matching rows.