SegmentMap is corrupted

[Ruslan Zasukhin]

On 13/2/07 9:49 PM, "Steve Albin" <steve at steve-albin.com> wrote:

Hi Steve,

> I looked on the Wiki for information on segmentmap, but there is nothing to be
> found.
> 
> I would like to know just what the error "SegmentMap is corrupted" means.

Segment Map:

    Volumes (.ind .dat) contain many internal logical files.
    i.e. Exists internal file sytem.

    remember FAT of DOS?
    or may be you know that MacOS have some kind of Tree file system?

So we have also Segment Map - based on tree area in volume which describe
location of logical files.

> My user is getting this error, but not in all instances of retrieving records.

Only in segments which have problems.

> He also reports that he can sometimes get a record and then have that same
> record retrieval fail on segmentmap error later in the program.
> 
> Is the segmentmap corruption something that can happen due to a bug in my app?
> What kind of thing could cause this?

This error can be expected in case of many new WRITE into db without Flush,
Then interrupt application (crash, system failure).
 
So you can try test your app:
    do some legal input your app allow
    and then Force Quite.

> When this error occurs, what is the prescribed method of trying to rescue the
> database?  Reindex? Clone DB?

clone

If .ind file is corrupted, then yes REINDEX can help,
Even better trash .ind file and open db again.

You can try DIAGNOSE db VERYHIGH.

> I tried cloning this DB using VStudio and it took 4 hours.  This is a 40MB
> database.  Is that an expected time frame for cloning a DB that size?

Seems very long. If you can, compressed db and put on some FTP for me.
We will profile later.

> I'm suspect of that clone function since I returned the DB to my user and the
> segment error still occurred.

Then you need ASK your user what steps he do.
And we need try reproduce this issue.

-- 
Best regards,

Ruslan Zasukhin
VP Engineering and New Technology
Paradigma Software, Inc

Valentina - Joining Worlds of Information
http://www.paradigmasoft.com

[I feel the need: the need for speed]