<(CM) Support tip>Unicode conversion increases DB size
Incident description :
After running DB Schema upgrade for CM/RM Database (ANSI type, SQL Server ) and DB Schema repair after the upgrade, significant increase in data file size for the database can be observed.
A small data file size increase (10% to 20% ) would be normal, however, if near or over 100% increase is observed, then Administrator needs to review and find out whether or not Unicode conversion was run as part of the Schema repair ( was run after the DB upgrade).
Unicode conversion converts String field ( convers it from data type varchar to data type nvarchar ) , and potentially this can increase the string data stored in the field by 100% ( byte length ) :
For the same string stored in varchar data type column, the character length remain unchanged after the conversion , but for the same length of character string, varchar data type take 1 byte per character, and nvarchar types take 2 bytes per character, hence after the Unicode conversion, a M byte length ( M characters, varchar ) will be converted to 2M bytes (M characters , nvarchar ), which doubled the byte size for the string stored in the column.