master detail crawls at slow speed

rbuser

I have a report with a subreport to print a master detail output. When I
qualify the queries with an extended where clause ( i.e.and condition =
value) then the report is instant.But when there is nothing in the where
clause it isdog slow.

It is as if in preparing the report, RBis re-evalutaing the detail query for
each record in preparing the report for each record in advance instead of
doing the second and subsequent pages in the background.

Is there a solution to only have the detail query evaluate only when
actually needed?.

nardmoseley

Here is an article on linking SQL queries. Use the second technique,
DataPipeline Linking, for the fastest performance...

------------------------------------------------------
Tech Tip: Linking SQL Queries for Master/Detail Data
------------------------------------------------------

The following example shows two options for linking SQL queries to create a
master/detail relationship.

In this example, we are using Delphi's DBDemos data to create a
Customer/Order relationship. Thus we wish to link the Orders detail to the
Customer master.

I. Delphi Query Linking
------------------------

a. Set the detail TQuery.DataSource property to point to the master
query's TDataSource component.

b. In the SQL "Where" clause for the detail query use a ':' followed by
the linking field name from the master:

example
select *
from orders
where orders.CustNo = :CustNo

Now each time the master record position changes, the detail query will
automatically be refreshed with the correct result set.


II. RB DataPipeline Linking
-----------------------------

a. Set the detail DataPipeline.MasterDataPipeline to point to the master
DataPipeline.

b. Use the detail DataPipeline.MasterFieldLinks property to define the
linking relationship

c. In the SQL for the detail, retrieve all records and sort them by the
linking master field:

select *
from Orders
order by CustNo


Notes:

1. Using RB DataPipeline, each query is executed only a single time - thus
performance is much faster.

2. RB Professional and Enterprise Editions include a visual Data environment
for creating SQL queries, defining linking relationships, and creating
Ask-At-Runtime parameters. Using the RB tools you could create the above
linked queries in about 10 seconds.


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rbuser

The datapipeline linking sorted it and it flies. I was using the first
method which was slow.