Question

Since I don’t know to calculate efficiency I’ll ask here and I hope someone could tell me what is better and explain it a bit.

The scenario:
Currently I have a table that insert rows of production of each worker.
Something like: (Worker1) produced (product10) with (some amount) for a Date.
And that goes for each station he worked in though the day.

The Question:
I need to generate a report of the sum of amounts that worker produced for each date. I know how to generate the report either way but the question is how is it more efficient?

Having to run a query for each person that sums up the production for each date? or having a table that I’ll insert the total amount, workerID and date?

Again if you could explain it a bit further it would be nice, if not than at least an educated answer would help me a lot with this problem.

Example:
This is what I have right now in my production table:

ID     EmpID     ProductID     Amount     Dateofproduction
----------------------------------------------------------
1      1         1             100        14/01/2013  
2      1         2             20         14/01/2012

This is what I want in the end:

EmpID    Amount    DateofProduction
-----------------------------------
1        120       14/01/2013

Should I start another table for this? or should I just sum what I have in the production table and take what I need?
Bear in mind that the production table will get larger and larger each day (of course).

Answer 1

i) Direct :

select EmpId, sum(Amount) as Amount, DateOfProduction 
from ProductionTable
group by EmpId, DateOfProduction.

ii) Now, the size of the table will keep growing. And you need only day-wise reports.

Is this table being used by anyone else? Can some of the data be archived? If some of the data can be archived, I would suggest, after each day and reporting, backup all the data from this table to a secondary archive table. So, every day you will have to query only today's worth of records.

Secondly, you can consider adding an index to DateOfProduction. You will then be able to restrict your queries in date range. For example, select EmpId, sum(Amount) as Amount, DateOfProduction from ProductionTable group by EmpId, DateOfProduction where DateOfProduction = Date(now()). (or something similar)

Because it is just a single table and no complicated queries, MySql will be easily able to take care of millions of records. Try EXPLAIN on the queries to check the number of records being touched and indexes being used.