I get this question all the time in the CCSA classes I teach, and the best way I've found to explain it is the following:
"Install Database" is more or less a subset of an "Install Policy" operation to a security gateway. Prior to starting the verification and compilation of a gateway's security policy, the SMS (and any other secondary SMS's or separate Log Servers) needs to "get its own house in order" by checking for any configuration changes on the SMS object or other Global Property settings that affect its own operation. This could be any change on the SMS object itself such as enabling the Compliance blade, the SmartEvent blade, a change in firewall log retention policy, and/or any changes made to locally-defined user accounts in the SmartDashboard/SmartConsole as mentioned above. If there are any changes detected the SMS implements them in its own live configuration before proceeding.
In R77.30 the "Install Database" operation invoked the command "fwm dbload" on the SMS which performed some or perhaps all of the "Install Database" operation, but I'm not sure if this command is still relevant in R80.10. Note that a publish operation in R80+ management simply commits proposed/candidate changes in an administrator's session to the SMS's postgres database configuration, and is a completely different type of operation.
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