I learned my software skills on the Ferranti Mercury computer. It had as I recall 468 words of memory (a word is about 6 bytes so call it 3k bytes). Let’s see, my phone has 8,000,000,000 bytes – that’s about 2.5 million times more. My phone makes the 1500 instructions per second look pretty silly as well.
The computer was big. The electronics used valves and they get hot. So each cabinet has a refrigerating unit built-in, and they were noisy.
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My COVID lockdown project is a system to keep a database updated called SUDSJS. I am using it to check out different database management systems (DBMS). The latest is CouchDB – and I like it
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I decided to use my lockdown project SUDSJS.com to test out a few different NOSQL database management systems (DBMS).
SUDSJS is written in JavaScript using the node.js server-side system and I designed it so that I could plug in different drivers for different databases. I wrote database drivers for MySQL, SQLite 3 and PostgreSQL. The first NOSQL system I tried was MongoDB, and the SUDSJS.com test site is currently running using this (correction – it is now running on CouchDB). The second NOSQL system I tried was Firestore from Google.
It didn’t go well.
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For the last 50 years there has been one and only one way of designing a database. SQL Database management systems (DBMS) have been the uncontested standard. (A better name is ‘relational’ because SQL is just the name of the language used to access them, but we will stick with it.)
But things have changed in the last 10-15 years. Databases that disobey relational rules are coming into vogue. The term NOSQL is used for these non-relational databases (the above chart is work in progress, but I have been looking at these systems.)
What is the difference between classic databases and this new breed?
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You know what an invoice looks like. We have all seen thousands of them – probably too many. But invoices illustrate an interesting problem – and I am not talking about your VAT return. I am talking about the new kids on the database block – document databases. An example is MongoDB. These can store all the data for one invoice in a single structured record (called a ‘document’).
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I am getting to the end of stage one in writing a database driver for MongoDB to use in my Lockdown Project sudsjs.com. All has gone well until I get to totalling up a field in the database. I had to enter the wonderful world of aggregation, which is powerful function-rich and confusing.
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I was looking at a page on the IBM website last week when something odd happened. Half the page loaded, then there was a spinning circle (a.k.a. a throbber) for a second or so, then the rest of the page loaded. The page itself is a few paragraphs of very boring text plus a menu. So why the drama with the throbber for a page like that?
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NOSQL databases like MongoDB are making a big splash in the computer industry. But are they set to replace the tried and tested technology of the past fifty years?
Here is my take on it, with a bit of history thrown in.
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As you get older (I’m 80) your brain slows down. This is a well-known fact. The defence against this is to keep it active and learn a new skill. I tried a new language (Spanish), but it turns out that if you are really bad at languages in your youth you are God-awfully bad in later years. So, I turned to something I did have a talent for – coding.
As we were stuck indoors anyway, courtesy of Covid, I thought I would update my knowledge of JavaScript, and something called Node.
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I went to see The Power of Yes yesterday. It is a very good explanation of the financial crisis as explained by a playwright – David Hare. I recommend it – the two hours flew by. However there was one small item I worried about. There was a comment about ‘Monte-Carlo methods’ being used by AIG which got a cheap laugh which I thought unfair. Monte Carlo methods are not about gambling – they are about minimising risk.
To explain (please bear with me I will get to the point):
The formula used to price a lot of the securities that caused the problem is the Black-Scholes formula – which one of the actors wrote up on a board. But the statement was made that it ‘predicts’ the future. Which is doesn’t; unless a statement like ‘if you flip a coin if will be heads 50% of the time’ can be said to be predicting the future. The Black-Scholes formula just says that if you assume that security prices vary at random then the price in x days time will be within certain limits y and z, except in very exceptional circumstances.
There are two assumptions built into this which are questionable. Continue Reading »
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