c-treeRTG COBOL Edition User's Guide

Performance Tips

The tips in this section can be implemented using client-side configuration keywords in the ctree.conf file. For server-side configuration (using ctsrvr.cfg), the general FairCom Server configuration suggestions apply to c-treeRTG.

Note: These tips require changes to the c-treeRTG configuration file (ctree.conf). They should be performed only by a developer or administrator who is familiar with your installation and with c-treeRTG configuration keywords.

The <optimisticadd> option enables adding keys before the data during WRITE operations. When <optimisticadd> is disabled, c-tree attempts to add unique keys before adding the data record. This eliminates the overhead of deleting a data record when the unique key check fails, speeding up the insert process. Disable <optimisticadd> if the COBOL application frequently performs WRITE operations conflicting with existing records.

See the documentation for <optimisticadd>.

Transaction Logging

In c-treeRTG V11 (but not the default isCOBOL installation), it can be helpful to disable transaction logging if transactions are not used. You can completely disable transactions if data is stored on secure media (hardware redundancy, etc.).

ctutil -tron, ctcbtran, cttrnmod (cttrnmod - Change Transaction Mode Utility, /doc/ctreeplus/cttrnmod-ChangeTransactionModeUtility.htm), the <transaction> keyword, and the section titled Transaction Processing Notes provide information about changing the transaction mode and transaction logging.

Enabling the <ctfixed> option forces creating fixed-length record data files as fixed-length c-tree files. If you enable <ctfixed>, you may see a small performance enhancement as there is additional overhead in processing variable-length record data files.

See the documentation for <ctfixed>.

c-treeRTG allows data compression so that less disk space is used, which results in performance enhancements while reading and writing to disk. Enabling <datacompress> using the RLE algorithm provides the advantages of compressed data with a very small impact on CPU usage. Since most applications are saturated at the I/O level, the slight increase in CPU usage but less overhead on the I/O channel typically results in performance gains. Note that RLE compression (which is the default) is usually the fastest algorithm.

See the documentation for <datacompress>.

Use <filepool> if files are frequently opened and closed. In COBOL applications it is common practice to close and re-open files for each procedure, which can cause unnecessary overhead. The <filepool> option keeps files open when the COBOL application requests to close them, allowing them to be available immediately when needed. Note: This may cause unexpected “file locked” situations when trying to open a file in exclusive mode if that file is kept open by the file pooling logic by another application.

See the documentation for additional details for the <filepool> keyword.

Use the <prefetch> option to improve performance of sequential reads. This option enables batch record retrieval to improve performance of consecutive sequential reads. It retrieves a specified number of records on the second consecutive sequential read. The next sequential read operations do not need to contact the server to retrieve records because they are now cached on the client side. Note: This might cause locking conflicts when an application attempts to write a record that has been prefetched and still buffered on the client.

See the documentation for the <prefetch> keyword.

ACUCOBOL in RM/COBOL Compatibility Mode

Some installations use ACUCOBOL in RM/COBOL compatibility mode so that reads on locked records are expected to be blocked until the lock goes away (or a timeout is reached). If you are using this mode, you may find it beneficial to use <retrylock> and <locktimeout> to avoid the COBOL runtime polling the server to check for locks. ACUCOBOL runtime implements blocking locks by attempting the lock in a loop (by performing multiple requests) until the lock is released or the timeout expires. Using <retrylock> avoids a lot of communication traffic by having the server waiting on a lock.

See the documentation for <retrylock> and <locktimeout>.

Use <memoryfile> on temporary files that do not need to be shared among applications. Use <temporary> on temporary files that may be shared among applications. Files set as <memoryfile> are not persisted to disk at all. Files set as <temporary> are persisted on disk but there is no guarantee of their consistency in case of disaster.

See the documentation for <memoryfile> and <temporary>.

KEEPOPEN

The FairCom Server KEEPOPEN configuration option (which can be enabled in ctsrvr.cfg) can improve performance if the application is frequently using OPEN/CLOSE.

See the KEEPOPEN keyword in the FairCom Server Administrator's Guide.

Shared Memory

The Shared Memory communication protocol can provide improved performance for clients and servers residing on the same machine.

See Shared Memory for c-treeRTG.

SQL Data

See the section titled SQL Considerations to understand the performance impact of hard-to-sqlize data.

The <batchaddition> keyword can be used to improve performance of consecutive record additions by caching the records on the client and sending to the server in one batch operation.

See the <batchaddition> keyword.

The <bulkaddition> keyword can improve performance of consecutive record additions by writing only the data record and postponing the key addition until the file is closed

See the <bulkaddition> keyword.

The <datacompress> and <keycompress> keywords to reduce disk space utilization and network traffic with a potential impact on performance.

See the <datacompress> and <keycompress> keywords.

The <optimisticadd> keyword enables and disables adding keys before the data during WRITE operations, which may improve performance in some situations.

See the <optimisticadd> keyword.

The <prefetch> keyword enables batch record retrieval to improve performance of consecutive sequential reads.

See the <prefetch> keyword.

The <smartcopy> keyword enables the use of batched read/write techniques to improve performance of file copy operations.

See the <smartcopy> keyword.