Product Documentation

FairCom ISAM for C

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Calculating Memory Usage

The FairCom Server startup memory requirements can be reasonably approximated with the following equation:

Base line Memory =

Server EXE size + 1 MB +

Communications Library size (if applicable) +

Data cache (DAT_MEMORY) +

Index buffer (IDX_MEMORY) +

(900 bytes * Number of files (FILES)) +

(325 bytes * Maximum number of connections (CONNECTIONS)) +

(16000 bytes * Number of actual connections) +

(256 bytes per connection per file actually opened))

Note the following points:

  • DAT_MEMORY and IDX_MEMORY default to 225,000 bytes each.
  • FILES defaults to 100.
  • CONNECTIONS default to 128.
  • IDX_MEMORY is the MAX of:
    • IDX_MEMORY or
    • 3 * CONNECTIONS * (PAGE_SIZE + 400), where PAGE_SIZE defaults to 8192.

The following locking/transaction processing related items should be considered when approximating the FairCom Server dynamic memory requirements:

  • Each record locked consumes 24 bytes.

For transaction processing files only:

  • Each data record written consumes (record length + 42) bytes.
  • Each index operation consumes (key length + 42) bytes.

See also:

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