Advantages of MD5 approach: For two users using same long URL,.Now check the DB (using technique 2 discussed above) to verify that TinyURL is not used already.Take the first 7 chars and use that to generate TinyURL.In this case, we might can’t use NoSQL as putIfAbsent feature support might not be available as the data is eventual consistency, even DB cant perform this operation.putIfAbsent(TinyURL, long URL) or INSERT-IF-NOT-EXIST and it Requires support from DB support.

So whats the solution? Adding TinyURL and long URL in DB, if there is no key whose value is equal to TinyURL i.e. If it was simply one server service then it might work, but we are talking about scale!! Problem: This technique creates race condition because it’s possible that two threads may be simultaneously adding same data to DB and may end up corrupting data.If tinyURL isn’t present in DB then put longURL and tinyURL in DB (put(tinyURL, longURL)).Checks whether generated tinyURL is present in DB (doing get(tiny) on DB).NOSQL: As you know the data is eventually consistent, but it is easy to scale and it is a highly available database Am not sure RDBMS will scale to this traffic!! We can use RDBMS which provides acid properties but the problem is scaling (yes you can shard but that increases the complexity of design) As we have 30M active users so there will be conversions and a lot of Short URL resolution and redirections - so hell lot of reads and writes. Or You can use first few characters of MD5(long_url) hash output. Lets use base62encoder? Base62 encoder contains A-Z, a-z, 0-9 total( 26 + 26 + 10 = 62) basically converting a base10 number to hash, whenever we get a long URL -> get a random number and convert to base62 and use the hash as short URL id. Given a long URL, how can we find hash function F that maps URL to a short alias Think about the number of reads and writes happens to the system!!!

In a Year 0.7284 TB and in 5 year 3.642 TB of data

expiration_length_in_minutes - 10 bytes.

short URL size of about 17 Bytes for 17 character.

Considering average long URL size of 2KB ie for 2048 characters.

Shortened URL can be combinations of numbers(0-9) and characters(a-Z) of length 7. If we are going to keep our service for 5 years, our service will generate about 1.8B records. If you are too lazy to read, I have made a video on the same topic - Subscribe to my channel Tech DummiesĬonsider we will have 30M service calls per month (1M calls/day).

URL shortening service, a web service that provides short aliases for redirection of long URLs.

Tiny url generator system design