Create a GUID in Java
java.util.UUID.randomUUID();
guid
Is there any difference between a GUID and a UUID?
The simple answer is: **no difference, they are the same thing. 2020-08-20 Update: While GUIDs (as used by Microsoft) and UUIDs (as defined by RFC4122) look similar and serve similar purposes, there are subtle-but-occasionally-important differences. Specifically, some Microsoft GUID docs allow GUIDs to contain any hex digit in any position, while RFC4122 requires certain values … Read more
Are GUID collisions possible?
Basically, no. I think someone went mucking with your database. Depending on the version GUID you’re using the value is either unique (for things like version 1 GUIDs), or both unique and unpredictable (for things like version 4 GUIDs). SQL Server’s implementation for their NEWID() function appears to use a 128-bit random number, so you’re … Read more
What are the performance improvement of Sequential Guid over standard Guid? [closed]
GUID vs.Sequential GUID A typical pattern it’s to use Guid as PK for tables, but, as referred in other discussions (see Advantages and disadvantages of GUID / UUID database keys) there are some performance issues. This is a typical Guid sequence f3818d69-2552-40b7-a403-01a6db4552f7 7ce31615-fafb-42c4-b317-40d21a6a3c60 94732fc7-768e-4cf2-9107-f0953f6795a5 Problems of this kind of data are:< – Wide distributions of … Read more
Advantages and disadvantages of GUID / UUID database keys
Advantages: Can generate them offline. Makes replication trivial (as opposed to int’s, which makes it REALLY hard) ORM’s usually like them Unique across applications. So We can use the PK’s from our CMS (guid) in our app (also guid) and know we are NEVER going to get a clash. Disadvantages: Larger space use, but space … Read more
How unique is the php session id
It’s not very unique as shipped. In the default configuration it’s the result of a hash of various things including the result of gettimeofday (which isn’t terribly unique), but if you’re worried, you should configure it to draw some entropy from /dev/urandom, like so ini_set(“session.entropy_file”, “/dev/urandom”); ini_set(“session.entropy_length”, “512”); search for “php_session_create_id” in the code for … Read more
How to create a GUID/UUID in Python
The uuid module provides immutable UUID objects (the UUID class) and the functions uuid1(), uuid3(), uuid4(), uuid5() for generating version 1, 3, 4, and 5 UUIDs as specified in RFC 4122. If all you want is a unique ID, you should probably call uuid1() or uuid4(). Note that uuid1() may compromise privacy since it creates … Read more
Simple proof that GUID is not unique [closed]
Kai, I have provided a program that will do what you want using threads. It is licensed under the following terms: you must pay me $0.0001 per hour per CPU core you run it on. Fees are payable at the end of each calendar month. Please contact me for my paypal account details at your … Read more
What are the best practices for using a GUID as a primary key, specifically regarding performance? [closed]
GUIDs may seem to be a natural choice for your primary key – and if you really must, you could probably argue to use it for the PRIMARY KEY of the table. What I’d strongly recommend not to do is use the GUID column as the clustering key, which SQL Server does by default, unless … Read more
How unique is UUID?
Very safe: the annual risk of a given person being hit by a meteorite is estimated to be one chance in 17 billion, which means the probability is about 0.00000000006 (6 × 10−11), equivalent to the odds of creating a few tens of trillions of UUIDs in a year and having one duplicate. In other … Read more