isCOBOL Evolve : SDK User's Guide : Files Management : Indexed Files
Indexed Files
Indexed files are file with an index that allows easy random access to any record given its file key. isCOBOL natively supports two kind of indexed files: JISAM and c-tree. A File Connector solution is available to access c-tree, Acucobol-GT (Vision) and Micro Focus files.
Comparison between JISAM and c-treeRTG
The table below shows the differences between JISAM and c-tree.
The objective of this comparison is to help the user in choosing the right file system depending on his needs.
 
JISAM
c-tree
maximum file size
9 EB
16 EB
maximum record size
2 GB
64 KB for fixed record length
2 GB for variable record length
maximum number of keys
no limit
no limit [A]
maximum key size
255 bytes
no limit
max number of segments per key
16
no limit [B]
maximum number of records
no limit
no limit
variable length records
not supported [C]
supported
transactions
not supported
supported
alternate collating sequence
supported
supported
OPEN INPUT WITH LOCK
not supported
supported
data encryption
supported[D]
supported
file compression
not supported
supported through configuration [E]
ODBC and JDBC access
supported via isCOBOL UDBC (separate product)
supported [F]
ODBC compliance
2.0
3.52
ADO.NET, PHP and Python
not supported
supported [F]
native dependences
no
yes
file handling utility
JUTIL
ctutil
monitor and tuning utilities
none
c-treeACEMonitor
c-treeGauges
c-treeISAMExplorer
c-treeLoadTest
c-treeLogAnalyzer
c-treePerfMon
c-treeTPCATest
DrCtree
backup features
none
integrated online backup
data replication
not supported
supported via c-tree Replication Agent (separate product)
memory files
not supported
supported
file pool
not supported
supported
[A] By default the maximum number of keys is 32, but it can be increased by setting MAX_DAT_KEY in the server configuration.
[B] By default the maximum number of segments is 16, but it can be increased by setting MAX_KEY_SEG in the server configuration.
[C] Variable length records are treated as fixed length records using the maximum record size.
[D] Encrypted JISAM files can’t be read via ODBC and JDBC.
[E] The compression is activated by the configuration properties iscobol.file.index.datacompress (boolean) and iscobol.file.index.keycompress (boolean). The WITH COMPRESSION clause in the SELECT statement is ignored.
[F] The SQL Engine requires a specific license. With the standard license SQL features are available only for three hours from the c-tree Server startup.