RE: What is the best way to do this?
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <michaeljmoore@xxxxxxxxx>, <adar666@xxxxxxxxxxxx>
- Date: Mon, 4 Apr 2011 15:35:52 -0400
It doesn't matter much about fetching a few (I think from what you've
written you have 15 total logical columns, or maybe it was 5) extra columns.
The point is to not dynamically parse all the time. In fact if you put a
trigger on data map to only rebuild them and recompile your function when
data map actually changes you'll be on the right track if data map changes
infrequently.
Just use the virtual column name to pick which of your columns to stuff into
the return function value.
Unless they prohibit you from reading data_map, you can still map out all
the attributes for each map_group and vastly reduce the amount of dynamic
sql and parsing at runtime. If you want the function to be as fast as it can
be at run time, that is how you do it.
Of course if you're wrong about the rate of change of data_map, then you'll
be compiling new versions of the function frequently. Then I'd back up to
Yechiel's idea, so you still have to parse it dynamically, and then the
trigger on data_map would just update the row in Yechiel's hypothetical
table for the data_map that had changed.
So how many distinct data_maps do you have?
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Michael Moore
Sent: Monday, April 04, 2011 1:20 PM
To: adar666@xxxxxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: What is the best way to do this?
Hi Yechiel,
I can't really do that because I am limited to modification only within my
PLSQL FUNCTION. I can not change the program that calls my function.
My task is to optimize/rewrite an existing function which looks like:
FUNCTION get_attribute_value (customer_number IN NUMBER,
virtual_column_name IN VARCHAR2)
returns varchar2;
-- where the return value is the value of one of ATTR001 thru ATTR201.
My function does not "know" all of the ATTRibute names, it only know the
ONE that it is currently processing.
There might be, for example, 31, 37 or 121 attributes that have a mapping
defined, but maybe only 1 of those attributes is required for pricing. For
example:
abc_key = 778899
customer # 12345
attribute07 = 3.5 -- student GPA
attribute121 = 95050 -- zip code
attribute129 = Agriculture -- program of interest
attribute134 = 25 -- age
Now lets assume that for this customer we have the business rule that says:
If the student's age > 23 charge the customer $21
If the student's age <= 23 charge the customer $29
My function will be passed (778899,'student_age')
My function will SELECT customer# from ABC where abc_key = 778899;
My function will figure out that for customer # 12345, 'student_age' is
stored in attribute134.
My function will select attribute134 from ABC where abc_key = 778899;
My function will return '25'
attribute07, 121 and 129 are completely irrelevant to my process as they
have no affect on the price.
Thanks for your help,
Regards,
Mike
On Sun, Apr 3, 2011 at 11:02 PM, Yechiel Adar <adar666@xxxxxxxxxxxx> wrote:
Based on your answers I think I will do this:
1) Create a new table that contain the customer number and the 5 attributes
that you need for each customer.
I mean, do a pivot on the data in data map and create one row for each
customer containing all the 5 fields you need.
You will need to recreate, or update, this table whenever the data map
table changed or when you add or delete a customer.
If you have, in data map, old customers that has no data in ABC then
you can filter out their mapping in this step.
2) Read the new table. ordered by customer id, and construct dynamic sql to
get only the fields you need from ABC.
This way, you do not read the big table and you accessed the fact table only
once for each customer and you save, big time, on network and database work
to put all the fields in your buffer.
This method also allow you to use bulk read for data map, saving more time.
You did not mentioned what partitioning you have, but if you partition data
map according to the field meaning,
I mean a partition for all "credit ratings", a partition for all "last
order" etc,
You can replace the the table in step one with select the will bring you
efficiently only the rows you need from the big table.
If you have old data map for customers that has no rows in ABC, you can do:
select * from data_map
where field_description in ('credit rating','last order')
and customer_id in (select customer_pk from ABC);
Yechiel Adar
Israel
On 02/04/2011 02:03, Michael Moore wrote:
Six questions:
1) How many customers?
26,000
2) Once established, can a customer's data_map change?
it's very rare
3) If the answer to #2 is no, or only vary occasionally and with a
defined maintenance event to reorganize that customer's data, how many
different data_map rows do you have?
1,700,000
5) Do you have partitioning?
yes
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