File Structures
Information regarding each file is kept in the file definition associated with the file's logical Label. The file's buffer is dynamically allocated upon program loading. It is limited to the available memory or 4GB, whichever is less (insufficient memory for buffer allocation may cause a CHAIN failure). The files created and their structure for each accessing method, are defined below:
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Type |
Description |
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One physical text file with the default 256 byte or the programmed (BUFFER/FIX/FIXED parameter) sector size is referenced. The sector size must be equal to or greater than the record length specified when the file was originally created. In addition, an AAM key file (.AAM) is also referenced, containing the hashed key information and associated logical record pointer for each record in the physical text file that has been AAMDEXed. The AAM file requires approximately 64K of disk space for each 2048 records (regardless of the number of keys or their size). | |
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BTRIEVE format data file. | |
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One physical text file with the default 256 byte or the programmed (BUFFER/FIX/FIXED parameter) sector size is referenced. | |
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One physical text file with the default 256 byte or the programmed (BUFFER/FIX/FIXED parameter) sector size is referenced. The sector size must be equal to or greater than the record length specified when the file was originally created. In addition, an ISAM key file (.ISI) is also referenced, containing the key information and associated logical record pointer for each record in the physical text file that has been indexed. |
See Also: Disk I/O Instructions
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