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Table fragmentation

Table fragmentation ( aTable ) : Real

ParameterTypeDescription
aTableTableTable for which to get the fragmentation rate
Function resultRealPercentage of fragmentation

Description

The Table fragmentation command returns the percentage of logical fragmentation for the records of the table designated by the aTable parameter.

The rate of logical fragmentation of the records indicates whether the records are stored in an ordered manner in the data file. If the fragmentation becomes too high, this can considerably slow down sorts and sequential searches on the table. A fragmentation percentage of 0 corresponds to no fragmentation. Beyond a rate of 20%, it may be useful to compact the data file.

Example

This maintenance method lets you request the compacting of the data file in the case where there is considerable fragmentation in at least one table of the database:

 ToBeCompacted:=False
 For($i ;1;Last table number)
    If(Is table number valid($i))
       If(Table fragmentation(Table($i)->)>20)
          ToBeCompacted:=True
       End if
    End if
 End for
 If(ToBeCompacted)
  // Places a marker requesting compacting
 End if

See also

Compact data file

Properties

Command number1127
Thread safe