Most users are satisfied
with the passage of shape files to the ArcGis geodatabase . However
, they notice a decrease in performance after editing heavy sessions.
Their issue is how to correctthis problem.
We will discuss in
this
article the concept of compacting a geodatabase
. As compression ( see with ArcGis 2- Geodabases Compression ),
compacting reduces the size of the ArcGIS geodatabase
in
order to speed up requests . However , compacting works
differently
compared to compression.
Except
in
loss compression, the compression, generally, erases
no
data byte from the geodatabase . It re-groups the data bytes
according
to the redundancy of information : if you have
ten lines with the value “8”, the compression will keep 10 (8)
instead of 8 8 8 8 8 8 8 8 8 8.
During
compacting, the process physically removes
and
cleans up the orphan (useless) records .
We
will show how to compact, but we must, firstly, understand
what
happens when editing the
geodatabase .
When you delete
a record , obviously , you could think
that these records are,
finally,
deleted
and that the sequence of records in the table go is taken to the next level to
fill the hole . However , this is
not exactly what happens; these
records
are
simply
marked
as
being
deleted
in
the geodatabase . If it were necessary to
reset
all
the records at each update the editing would take too much time.
This
is why the software only marks the records as
deleted
and
ignores these recordings in
all
future requests. So what happens
when you try to locate a record ?
The
program must browse all the
records and, if the record is
marked as erased it
advances to the next , otherwise it checks whether it matches the request or not .
Although
they are deleted , they are ,
in a way , the reason for the slowing down of the query.
So how does the compacting exactly work? As you will have, already, guessed , compacting performs the removal of these recordings and all the others orphans who are not being used or referenced by others objects . This is why compacting speeds up geodatabases file and personal (access) queries.
It’s easy to compact a geodatabase file
or
access. It is recommended
to compact a geodatabase after a heavy
editing session.
To
compact a geodatabase file or access,
perform the following steps:
1. Open ArcCatalog and select the
geodatabase to compact.
2. Right- click to open the
context menu , select Administration, then
click Compact Geodatabase
There are no counter indications for compacting .
It is somehow like the hard disk
defragmentation: it does not accelerate if it is
not necessary but it
does not slow down the processing.
For
more information, please visit the ArcGIs
Online Help(ESRI)
In the following (and final) article
we will discuss how to perform the compacting and the geodatabases saving with
a single click
by
setting up a processing model with Model Builder.
