读取文件或在数据库中搜索？

Question

I am creating a web-based app for android and I came to the point of the account system. Previously I stored all data for a person inside a text file, located users/<name>.txt. Now thinking about doing it in a database (like you probably should), wouldn't that take longer to load since it has to look for the row where the name is equal to the input?

So, my question is, is it faster to read data from a text file, easy to open because it knows its location, or would it be faster to get the information from a database, although it would have to first scan line by line untill it reaches the one with the correct name?

I don't care about the safety, I know the first option is not save at all. It doesn't really matter in this case.

Thanks,

Merijn

Answer 1

In any question about performance, the first answer is usually: Try it out and see.

In your case, you are reading a file line-by-line to find a particular name. If you have only a few names, then the file is probably faster. With more lines, you could be reading for a while.

A database can optimize this using an index. Do note that the index will not have much effect until you have a fair amount of data (tens of thousands of bytes). The reason is that the database reads the records in units called data pages. So, it doesn't read one record at a time, it reads a page's worth of records. If you have hundreds of thousands of names, a database will be faster.

Perhaps the main performance advantage of a database is that after the first time you read the data, it will reside in the page cache. Subsequent access will use the cache and just read it from memory -- automatically, I might add, with no effort on your part.

The real advantage to a database is that it then gives you the flexibility to easily add more data, to log interactions, and to store other types of data the might be relevant to your application. On the narrow question of just searching for a particular name, if you have at most a few dozen, the file is probably fast enough. The database is more useful for a large volume of data and because it gives you additional capabilities.