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Differences between READ/FIND/HISTOGRAM

 
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monasu1998

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Joined: 23 Dec 2005
Posts: 176
Location: India

PostPosted: Wed May 16, 2007 12:46 pm    Post subject: Differences between READ/FIND/HISTOGRAM
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Hi All,
I am working in a Natural/Adabas environment.

I have very brief idea about these statemsnts(in subject line).
Can someone elaborate these three statements also publish when to use whaich statement. Which is preferrable in terms of resource consuption and Adabas Calls


10X
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ofer71

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Joined: 27 Dec 2005
Posts: 2360
Location: Israel

PostPosted: Wed May 16, 2007 3:05 pm    Post subject:
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This is from Software-AG's fine manuals:


READ
The READ statement is used to read records from a database. The records can be retrieved from the database:
  • in the order in which they are physically stored in the database
    (READ IN PHYSICAL SEQUENCE), or
  • in the order of Adabas Internal Sequence Numbers
    (READ BY ISN), or
  • in the order of the values of a descriptor field
    (READ IN LOGICAL SEQUENCE).


FIND
The FIND statement is used to select from a database those records which meet a specified search criterion.


HISTOGRAM
The HISTOGRAM statement is used to either read only the values of one database field, or determine the
number of records which meet a specified search criterion.
The HISTOGRAM statement does not provide access to any database fields other than the one specified in the
HISTOGRAM statement.

O.
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ofer71

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PostPosted: Wed May 16, 2007 3:51 pm    Post subject:
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We are always looking for an experienced ADABAS/NATURAL programmers here in Israel.

Interested?

O.
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verbor

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Joined: 17 May 2007
Posts: 1
Location: Israel

PostPosted: Thu May 17, 2007 1:41 pm    Post subject: Yes
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Yes, I am interested.

ofer71 wrote:
We are always looking for an experienced ADABAS/NATURAL programmers here in Israel.

Interested?

O.
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monasu1998

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Joined: 23 Dec 2005
Posts: 176
Location: India

PostPosted: Tue May 22, 2007 10:32 am    Post subject:
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Hello Ofer,


Could you please let us know in what scenarios (Apart from the generic Definations) we should use READ/FIND and HISTOGRAM?

Thanks Much,
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ofer71

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PostPosted: Thu May 24, 2007 11:09 am    Post subject:
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You use READ/FIND when you want to read data records from ADABAS; You usually use HISTOGRAM to count the number of records matching a specific criteria.

O.
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Adam

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Joined: 17 Jun 2005
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PostPosted: Wed May 30, 2007 4:08 pm    Post subject:
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You usually use READ to read sequentially large number of records by some descriptor.
The FIND is rather for direct access to small amount of records of database.
The HISTOGRAM use only index part of database so it works quickly.
Regards
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dr_te_z

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Joined: 08 Jun 2007
Posts: 71
Location: Zoetermeer, the Netherlands

PostPosted: Mon Aug 13, 2007 1:48 pm    Post subject:
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Rule of thump:

If you can obtain your data using HISTOGRAM: do so!
else
use the good old 80/20 rule:

do you need to access 20% or less from a table?
then code FIND
else code READ
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Raj Kiran

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Joined: 24 Aug 2007
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Location: Chennai

PostPosted: Fri Aug 24, 2007 3:51 pm    Post subject:
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Read is best when there are more reords to be read.

find is best when u know the value descriptor or superdescriptor of record to be fetched

Actual usage of Histogram comes when the super descriptor is having a PE feild in such case Read and find wont work properly in this case Histogram works fine
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