Product Documentation

Database Administrator's Guide

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SET_FILE_CHANNELS <file name>#<nbr of I/O channels>

Without this feature, the ctDUPCHANEL file mode bit enables a file to use NUMCHANEL simultaneous I/O channels, where NUMCHANEL is set at compile time, and is by default, set to two (2). For superfile hosts with ctDUPCHANEL, 2* NUMCHANEL I/O channels are established. The default is not to turn on ctFeatCHANNELS.

SET_FILE_CHANNELS permits the number of I/O channels to be explicitly set for the named file regardless of whether the file mode, at open, includes ctDUPCHANEL. A value of one (1) for the number of I/O channels effectively disables ctDUPCHANEL for the file. A value greater than one (1) turns on DUPCHANEL and determines the number of I/O channels used. The number of I/O channels is not limited by the compile-time NUMCHANEL value. You may have as many SET_FILE_CHANNELS entries as needed.

The <file name> can be a wildcard specification using a ‘?’ for a single character and a ‘*’ for zero or more characters. See FairCom DB Standard Wildcards.

Note: Multiple I/O channels are disabled for newly created files. The multiple I/O channels take affect only on an open file call. Also, depending on the default number of I/O channels, a superfile host not in the SET_FILE_CHANNELS will use no more than 2 * NUMCHANEL I/O channels.

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