Hi Chanaka,
whether and how much a query can benefit from IWA depends very much on the query itself.
Typically, the queries that benefit most are OLAP-type queries. These usually are quite complicated,
require the database server to examine millions of rows, possibly do some sort of aggregation, but
then produce few result records. The processing of such queries often not only causes a lot of I/O,
like whole table scans, but also is CPU intensive.
With IWA, such a query can benefit because IWA keeps all required data in memory, hence no I/O
is required. And with a lot of CPU power available on the IWA machine (or even an IWA cluster), the
CPU intensive processing can be completed faster. As usually few data records are produced as
result, little network bandwidth is consumed by transferring such small result sets from IWA to the
Informix server (and on to the database client).
When such "heavy queries" get off-loaded from the Informix server machine to the IWA machine(s),
other users will benefit as well, because the Informix server itself is not busy with executing the
query. It lets IWA do the heavy lifting.
Having said this, it also becomes clear that not all types of queries can benefit (much) from IWA.
If, for instance, the Informix server is able to use an index to retrieve few required data records from
a huge table, then this may even be faster than with IWA acceleration. Also, queries that return a
large result set to the database client may not benefit from IWA, because of the overhead of
transferring such large result sets from IWA to the Informix server.
From the rather short description you have given, it seems that the customer's scenario very much
looks like the latter case: a query that produces a large result set?
Of course, with such queries it may be possible to look at the application and its concept and figure
out, whether and how it is possible to transfer processing of large result sets from the application
into the database server - and from there to IWA ...
I hope this short answer can help. For more in depth information, I would like to recommend the
"IWA Redbook" (title "Query Acceleration for Business using IBM Informix Warehouse Accelerator")
Regards, Martin
--
Martin Fuerderer Informix Development Germany
| HCL Technologies Germany GmbH Frankfurter Ring 17 80807 Munich, Germany http://www.hcltech.com/de |
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