It might be helpful at this point to illustrate the way the user and message databases work together. Figure 4.6 shows the relationship between user and message databases. Figure 4.6. The connection between user and message databases
In the example shown in Figure 4.6, the user assigned to USER123.DB has sent a message to another user. USER123.DB is assigned to send through MSG17.DB, and has sent to USERABC.DB. The following numbered items correspond to the numbered arrows in Figure 4.6:
From this simplified illustration, you can see that even if a dozen users on a post office have a copy of a message in their inbox, that message record exists only once in the appropriate message database. An attachment sent to several people is written to only one BLOB file. |