Adobe 38000827 Administration Guide - Page 19

The following table compares these storage options: Storage type Advantages Data source • Can use existing data source • Portable: not tied to the host system or operating system Browser cookies • Simple implementation • Good performance • Can be set to expire automatically • Client-side control System registry • Simple implementation • Good performance • Registry can be exported easily to other systems • Server-side control Disadvantages • Requires database transaction to read/write variables • More complex to implement • Users can configure browsers to disallow cookies • ColdFusion MX limits a cookie's data to 4 KB • Netscape Navigator allows only 20 cookies from one host; ColdFusion MX uses three cookies to store read-only data, leaving only 17 cookies available • Possible restriction of the registry's maximum size limit on Windows in the Control Panel • Integrated with the host system: not practical for clustered servers • Solaris, Linux, and HP-UX registries are text files. Their registries deliver slow performance and low scalability. Migrating client variable data To migrate your client variable data to another data source, you should know the structure of the database tables that store this information. Client variables stored externally use two small database tables, like those shown in the following tables: CDATA Table Column cfid app data Data type CHAR(64), TEXT, VARCHAR, or equivalent CHAR(64), TEXT, VARCHAR, or equivalent MEMO, LONGTEXT, LONG VARCHAR, or equivalent CGLOBAL Table Column Data type cfid CHAR(64), TEXT, VARCHAR, or equivalent data MEMO, LONGTEXT, LONG VARCHAR, or equivalent lvisit TIMESTAMP, DATETIME, DATE, or equivalent Server Settings section 11