Using Caché Multi-Dimensional Storage - InterSystems ...

Introduction
^Settings("Auto1","Properties","Color") = "Red"
^Settings("Auto1","Properties","Model") = "SUV"
^Settings("Auto2","Owner") = "Mo"
^Settings("Auto2","Properties","Color") = "Green"
Globals have the following features:
• Simple to Use — Globals are as easy to use as other programming language variables.
There is a comprehensive set of commands in both the Caché ObjectScript language and
the Basic scripting language that make it extremely easy to use globals within applications.
• multidimensional — You can specify the address of a node within a global using any
number of subscripts. For example, in ^Settings("Auto2","Properties","Color"),
the subscript Color is a third-level node within the Settings global. Subscripts can be
integer, numeric, or string values, and need not be contiguous.
• Sparse — The subscripts used to address global nodes are highly compacted and need
not have contiguous values.
• Efficient — The operations on globals — inserting, updating, deleting, traversing, and
retrieving — are all highly optimized for maximum performance and concurrency. There
are additional commands for specialized operations (such as bulk inserts of data). There
is a special set of globals designed for temporary data structures (such as for sorting
records).
• Reliable — The Caché database provides a number of mechanisms to ensure the reliability
of data stored within globals, including both logical-level and physical-level journaling.
Data stored within globals is backed up when a database backup operation is performed.
• Distributed — Caché provides a number of ways to control the physical location of data
stored within globals. You can define a physical database used to store a global, or distribute
portions of a global across several databases. Using the distributed database features
of Caché, you can share globals across a network of database and application server
systems. In addition, by means of data shadowing technology, data stored within globals
on one system can be automatically replicated on another system.
• Concurrent — Globals support concurrent access among multiple processes. Setting and
retrieving values within individual nodes (array elements) is always atomic: no locking
is required to guarantee reliable concurrent access. In addition, Caché supports a powerful
set of locking operations that can be used to provide concurrency for more complex cases
involving multiple nodes. When using Object or SQL access, this concurrency is handled
automatically.
• Transactional — Caché provides commands that define transaction boundaries; you can
start, commit, or rollback a transaction. In the event of a rollback, all modifications made
2 Using Caché Multi-Dimensional Storage