Micro Focus Frequent Contributor
Micro Focus Frequent Contributor

<(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.

Resolution                :

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. 

Reference : 



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