Additional size limitations on a replicated database

The addition of three fields (s_GUID, s_Lineage, and s_Generation) imposes two limitations on your replicated tables:

• The Microsoft Jet database engine allows a maximum of 2,048 bytes (not counting Memo or OLE Object fields) in a record. Replication uses a minimum of 54 bytes to store unique identifiers, indexes, and information about changes to the record. If the record contains either Memo or OLE Object fields, replication uses an additional 4 bytes for each of those fields. The total number of bytes available in a record in a replicated table can be calculated as follows:

  2,048 bytes
  - 54 bytes for replication overhead
  - (4 bytes * the number of Memo fields)
  - (4 bytes * the number of OLE Object fields)
  = the maximum number of bytes available

• The Microsoft Jet database engine allows a maximum of 255 fields in a table, of which at least three fields are used by replication. The total number of fields available in a replicated table can be calculated as follows:

  255 fields
  - 3 system fields
  - the number of Memo and OLE Object fields
  = the number of fields available

Few well-designed applications use all the available fields in a table or all the bytes in a record. However, if you have a large number of Memo or OLE Object fields in your table, you might run into constraints.

Note   In addition to setting limits on the available number of characters and fields, the Microsoft Jet database engine also limits the number of nested transactions allowed. You can have a maximum of seven nested transactions in a nonreplicated database, but a replicated database can have a maximum of six nested transactions.

The addition of several new system tables also adds to the size of your database. Most of these new tables contain only a few records, but some of the new tables can grow significantly, depending upon the frequency of synchronization between replicas.

The size of your database file is significant for two reasons:

• The Microsoft Jet database engine supports files up to a maximum of 1 gigabyte in size, but many users have limited space available on their hard disks. A replicated database that is larger than the original database file might use up a significant portion of the available disk space.
  
  
• If you choose to make a backup copy of the nonreplicable form of your database, you must have sufficient space on your hard disk for both the replicated database and the backup copy.
  
  
• Note   For other considerations associated with a Microsoft Access project, click .