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  SET TURBOREAD:

  Syntax:

  SET TURBOREAD [ON | OFF]

  This command allows you to turn-off the automatic locking of index
  files during certain read-only processes, ie: SEEK, GO TOP, SKIP, FIND,
  etc.  This powerful feature has one serious side-effect:  IT ALLOWS
  OTHERS TO UPDATE YOUR INDEX WHILE YOU ARE SEARCHING IT!  Basically,
  this means that even though your SEEK may return a FOUND() = .T.
  status, if the index was changed during the SEEK process, it would not
  necessarily be accurate.  That's why we call it a "dirty" read. <g>

  To offer some type of solution to this integrity problem, semaphore
  management functions (Sx_MakeSem(), Sx_KillSem(), etc) have been included
  so that you may have a mechanism through which you can inform other network
  users that you are in the SEEK process.  With this, they can be forced to
  wait until your process is complete before performing the index file
  update.

  NOTE: Using this function, while somewhat risky, will improve your
        network performance by up to 100%, so weigh the options carefully.

    NOTE:  This command is NOT supported under SIXNTX.

  Example:

    /*
        This program demonstrates the speed difference dirty read makes when
        skipping though a shared database.
    */

    #include "SIXNSX.CH"

    LOCAL nStart, nEnd

    SET EXCLUSIVE OFF         // Make SHARED the default

    USE TEST VIA "SIXNSX"     // Open up the TEST database
    INDEX ON last TO last     // Build an index; Since it's exclusive after
    CLOSE DATA                //  just creating it, close the database and
    USE TEST VIA "SIXNSX"     //  reopen it
    SET INDEX TO LAST         // Then set our index active again

    ? "Skip test - shared"
    ?
    nStart := Seconds()       // Save starting time
    FOR nCnt := 1 TO 240      // Cruise through the database for a bit
      ?? "."                  // Print a dot
      DO WHILE !eof()         // Skip to the end of the file
        SKIP
      ENDDO
      DO WHILE !bof()         // Skip back to the beginning of the file
        SKIP -1
      ENDDO
    NEXT
    nEnd := Seconds()         // Save ending time

    ? "Elapsed time:", nEnd - nStart, "seconds"
    ?

    // Now turn dirty read on
    SET TURBOREAD ON

    ? "Skip test - shared with dirty read on"
    ?
    nStart := Seconds()       // Save starting time
    FOR nCnt := 1 TO 240      // Cruise through the database for a bit
      ?? "!"                  // Print an exclamation point
      DO WHILE !eof()         // Skip to the end of the file
        SKIP
      ENDDO
      DO WHILE !bof()         // Skip back to the beginning of the file
        SKIP -1
      ENDDO
    NEXT
    nEnd := Seconds()         // Save ending time

    ? "Elapsed time:", nEnd - nStart, "seconds"