Get database parameter

version 11.3 (Modified)

Get database parameter ({aTable; }selector{; stringValue}) Longint

The Get database parameter command allows you to get the current value of a 4D database parameter. When the parameter value is a character string, it is returned in the stringValue parameter.

The selector parameter designates the parameter to get. 4D offers you the following predefined constants, which are in the "Database Parameters" theme:

To know the values that could be returned by this function, as well as the scope of each selector and whether or not any changes made are kept between sessions, please refer to the description of the SET DATABASE PARAMETER command.

The Database Cache Size (9) selector allows you to get the current database memory cache size. The returned value is expressed in bytes.

The Maximum Cache size is set on the "Database/Data Management" page of the Preferences. The actual size allocated to the database cache however will depend on both the settings and the current system resources. The Get database parameter command allows you to get the actual size of the memory allocated to the database cache by 4D.

Note: You cannot set the database cache memory size using the language. In other words, the Database Cache Size selector cannot be set using the SET DATABASE PARAMETER command.

When you use the WEDD Signature (36) selector with this command, the string defined as the WEDD signature is returned in the optional stringValue parameter and the function returns 0.

1. The following method allows you to get 4D scheduler current values:

   C_LONGINT($ticksbtwcalls;$maxticks;$minticks;$lparams)
   If (Application type=4D Local Mode) ` 4D local mode is used
      $lparams:=Get database parameter(4D Local Mode Scheduler)
      $ticksbtwcalls:=$lparams & 0x00ff
      $maxticks:=($lparams>>8) & 0x00ff
      $minticks:=($lparams>>16) & 0x00ff
   End if

2. The selector 16 (IP Address to listen) lets you get the IP address on which the 4D Web server receives HTTP requests. The following example splits up the hexadecimal value:

   C_LONGINT($a;$b;$c;$d)
   C_LONGINT($addr)
   $addr:=Get database parameter(IP Address to listen)
   $a:=($addr>>24)&0x000000ff
   $b:=($addr>>16)&0x000000ff
   $c:=($addr>>8)&0x000000ff
   $d:=$addr&0x000000ff

DISTINCT VALUES, QUERY SELECTION, SET DATABASE PARAMETER.