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The storage policies currently supplied as static members of
the StoragePolicy
class
are as follows:
-
PREFER_MEMORY
- Stores table data in memory.
Currently implemented using an
ArrayList
of
Object[]
arrays.
-
PREFER_DISK
- Generally attempts to store data in a temporary disk file,
though in the case that this is impossible (e.g. SecurityException)
will fall back to memory-based storage. May also use memory
for rather small tables.
The temporary disk file is written to the default temporary
directory, and will be deleted when the RowStore is
garbage collected, or on normal termination of the JVM.
This is currently implemented using mapped file access and
row-oriented storage of data.
-
DISCARD
- Metadata is retained, but the rows are simply thrown away.
The table returned from the row store has a row count of zero.
A policy which uses column-oriented disk-based storage may be
forthcoming in the future; this would have different performance
characteristics to the row-oriented one.
You are quite at liberty to implement and use your own
StoragePolicy
objects, possibly on top of existing ones.
For instance you could implement one which stored only the first
ten rows of any array.
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STIL - Starlink Tables Infrastructure Library
Starlink User Note
252
STIL web page:
http://www.starlink.ac.uk/stil/
Author email:
m.b.taylor@bristol.ac.uk
Starlink: http://www.starlink.ac.uk/