I currently have a MySQL database which deals a very large number of transactions. To keep it simple, it's a data stream of actions (clicks and other events) coming in real time. The structure is such, that users belong to sub-affiliates and sub-affiliates belong to affiliates.
I need to keep a balance of clicks. For the sake of simplicity, let's say I need to increase the clicks balance by 1 (there is actually more processing depending on an event) for each of - the user, for the sub-affiliate and the affiliate. Currently I do it very simply - once I receive the event, I do sequential queries in PHP - I read the balance of user, increment by one and store the new value, then I read the balance of the sub-affiliate, increment and write, etc.
The user's balance is the most important metric for me, so I want to keep it as real time, as possible. Other metrics on the sub-aff and affiliate level are less important, but the closer they are to real-time, the better, however I think 5 minute delay might be ok.
As the project grows, it is already becoming a bottleneck, and I am now looking at alternatives - how to redesign the calculation of balances. I want to ensure that the new design will be able to crunch 50 million of events per day. It is also important for me not to lose a single event and I actually wrap each cycle of changes to click balances in an sql transaction.
Some things I am considering:
1 - Create a cron job that will update the balances on the sub-affiliate and affiliate level not in real time, let's say every 5 mins.
2 - Move the number crunching and balance updates to the database itself by using stored procedures. I am considering adding a separate database, maybe Postgress will be better suited for the job? I tried to see if there is a serious performance improvement, but the Internet seems divided on the topic.
3 - Moving this particular data stream to something like hadoop with parquet (or Apache Kudu?) and just add more servers if needed.
4 - Sharding the existing db, basically adding a separate db server for each affiliate.
Are there some best practices / technologies for this type of task or some obvious things that I could do? Any help is really appreciated!
My advice for High Speed Ingestion is here. In your case, I would collect the raw information in the ping-pong table it describes, then have the other task summarize the table to do mass UPDATEs of the counters. When there is a burst of traffic, it become more efficient, thereby not keeling over.
Click balances (and "Like counts") should be in a table separate from all the associated data. This helps avoid interference with other activity in the system. And it is likely to improve the cacheability of the balances if you have more data than can be cached in the buffer_pool.
Note that my design does not include a cron job (other than perhaps as a "keep-alive"). It processes a table, flips tables, then loops back to processing -- as fast as it can.