Comparison between JISAM and c-treeRTG

The table below shows the differences between JISAM and c-treeRTG.

The objective of this chapter is to help the user in choosing the right file system depending on his needs.

	JISAM 1	JISAM 2	c-tree
maximum file size	2 GB	9 EB	16 EB
maximum record size	32 KB	2 GB	2 GB
maximum number of keys	no limit	no limit	no limit [A]
maximum key size	256 bytes	256 bytes	no limit
max number of segments per key	8	16	no limit [B]
maximum number of records	no limit	no limit	no limit
variable length records	not supported [C]	not supported [C]	supported
transactions	not supported	not supported	supported
alternate collating sequence	not supported	supported	supported
data encryption	supported	supported	supported through configuration [D]
file compression	not supported	not supported	supported through configuration [E]
ODBC and JDBC access	through isCOBOL File Server and isCOBOL UDBC	through isCOBOL File Server and isCOBOL UDBC	only with SQL features
native dependences	no	no	yes
file handling utility	JUTIL	JUTIL	ctutil

[A] By default the maximum number of keys is 32, but it can be increased by setting MAX_DAT_KEY <number_of_indices> in the server configuration.

[B] By default the maximum number of segments is 12, but it can be increased by setting MAX_KEY_SEG <number_of_segnments> in the server configuration.

[C] Variable length records are treated as fixed length records using the maximum record size.

[D] The data encryption is activated by the iscobol.file.index.encrypt (boolean) configuration property.

[E] The compression is activated by the configuration properties iscobol.file.index.datacompress (boolean) and iscobol.file.index.keycompress (boolean).

NOTE - Please note that JISAM 2 is supported only by isCOBOL 2009 SP2 and higher. Previous versions of isCOBOL are not able to handle this file system.