Table fragmentation
Table fragmentation ( aTable ) -> Function result
| Parameter | Type | Description | |
|---|---|---|---|
| aTable | Table | → | Table for which to get the fragmentation rate |
| Function result | Real | ← | Percentage 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