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Building a Parse Tree From an SQLDA

IP.com Disclosure Number: IPCOM000100272D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Yothers, JA: AUTHOR

Abstract

In a Distributed Data Base environment supporting SQL SELECT statements, there are at least two Data Base Systems; the one containing the data to be retrieved, and the one at which the SQL SELECT statement is received. The Data Base System at which the SQL SELECT statement is received is termed the "Requesting Site". The Data Base System at which the data is stored and which responds to the request for data from the Requesting Site is termed the "Responding Site". The process of sending the request for data from the Requesting Site to the Responding site is termed "Function Shipping".

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Building a Parse Tree From an SQLDA

       In a Distributed Data Base environment supporting SQL
SELECT statements, there are at least two Data Base Systems; the one
containing the data to be retrieved, and the one at which the SQL
SELECT statement is received.  The Data Base System at which the SQL
SELECT statement is received is termed the "Requesting Site".  The
Data Base System at which the data is stored and which responds to
the request for data from the Requesting Site is termed the
"Responding Site".  The process of sending the request for data from
the Requesting Site to the Responding site is termed "Function
Shipping".

      Once the SELECT statement representing the request for data has
been sent to the Responding Site and the description of the answer
set has been returned to the Requesting Site, in the form of an
SQLDA, the parse tree representing the original SELECT statement is
no longer of any use to the Requesting Site.  This is because all of
the functions necessary to satisfy the request for data are being
performed by the Responding Site.  While these functions may be quite
complex, the processing necessary at the Requesting Site is merely to
return the data to the application program as it is sent from the
Responding Site.

      Since the original parse tree is of no use to the Requesting
Site, it is discarded and must be replaced by another one that
describes the processing necessary at the Requesting Site.  Even
though no SQL sta...