IDB logo InstantDB

Advanced
Networking
tuning
Transactions
Readonly mode
Import/export
Jdbc
Triggers
Encryption

Readonly Mode

InstantDB can open a database in readonly mode. This is primarily intented to allow the database to operate from read only file systems, and in particular from CD-ROMs.

The two main property settings which are required in the database's .prp file are:

readOnly=1
transLevel=0

With both of these set as shown, the database will open all existing tables in readonly mode. Transaction processing is disabled to prevent the need to access the journal file.

If very large results sets are anticipated, then care should be taken to ensure that sufficient virtual memory will be available and that excessive paging will not be generated.

Tracing can remain enabled, provided the trace log points to a writable part of the file system.


Reducing the Size of InstantDB

InstantDB already has a very small memory footprint. However, where distribution is costly, say over dial up links, the size of InstantDB can be reduced even further.

Besides the usual technique of encapsulating the database classes in a zip or jar file, it is possible to dispense with many of the InstantDB classes entirely. All of the following classes can be dispensed with where they are not specifically required.

  • BlobColumn.class
  • CurrencyColumn.class
  • DateColumn.class
  • DoubleColumn.class
  • FloatColumn.class
  • LongColumn.class
  • BTree.class (if ORDER BY not used)
  • idbTrigger.class
  • idbPreparedStatement
  • idbDatabaseMetaData
  • Importer
  • JdbcImporter
  • Tableencrypt