It is looking increasingly like I’ll have to go live before I have had the time to tweak all the queries/tables etc, before I go live with a website (already 6 months behind schedule, so all though this is not the ideal scenario – thats how things are).
Its now a case of having to bite the bullet. Its just a case of trying to work out how big that bullet will be when we come to ‘biting it’. Once the databse goes live obviously we cant change the data on a whim, because its live data. I am fairly confident on the most of db schema – for e.g. the tables are in most 3 and 4th normal form, and constraints are used to ensure data integrity. I have also put in some indexes on some column that (I think) will be used a lot in queries though this was done quite hurridly and not tested – this is the bit I am worried about.
To clarify, I am not talking about wholesale structure change. The tables themselves are unlikely to change (if ever), however it is almost guaranteed that I will have to tune the tables at some stage (either personally or by hiring someone).
I want to know how much of a task this is. Specifically, assuming a database of a few gigabytes (so far roughly 300 tables)
Assuming 50% of the tables need tuning in the next few months:
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How long will it take to perform the tuning (I know this is a “how long is a piece of string” type question) – but what are the main determinants of the effort required, so I can work out how long it is likely to take?
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Is it possible to either lock sections of the database, (or specific tables) whilst the indexes are being reworked, or does the entire databse need to go offline? (I am using mySQL 5.x as the db)
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Is what I describe (going live before ALL tables perfectly tuned) outrageously risky/inadvisable ? (Does it justify the months of sleepless nights this has caused me so far) ?
I would try at least to quantify the limits of the database before going live, so that at least you would know when the activity generated from your application is getting near to that threshold.
You may want to simulate (automatically as much as possible) the typical usage of the database from your application, and check how many concurrent users/sessions/transactions, etc it can handle before it breaks. This, at least, should allow you to solve the “sleepless nights” issue.
As for the original “How easy is it…?” question, the answer obviously depends on many factors. However, the above analysis would undoubtedly help, as at the very least you will be in a position to say whether your database requires tweaking or not.