uuid

问题 I want to have a UUID column in a pyspark dataframe that is calculated only once, so that I can select the column in a different dataframe and have the UUIDs be the same. However, the UDF for the UUID column is recalculated when I select the column. Here's what I'm trying to do: >>> uuid_udf = udf(lambda: str(uuid.uuid4()), StringType()) >>> a = spark.createDataFrame([[1, 2]], ['col1', 'col2']) >>> a = a.withColumn('id', uuid_udf()) >>> a.collect() [Row(col1=1, col2=2, id='5ac8f818-e2d8-4c50

问题 I have a Java/JPA/Hibernate/MySQL based app. I want to use UUIDs for object identity, however I want to ensure database performance does not suffer. I found this great blog posting JPA and UUID Primary Keys which gets me some of the way there. Notice how the storage of the UUID is optimized by storing it in binary form (versus the string representation. It solves part of the problem, because now we can insert objects efficiently into the database. However, now I have an issue when I want to

问题 I'm wanting to use UUIDs in an app I'm building and am running into a bit of a problem. Due to UUIDs (v4) not being sortable because they're randomly generated, I'm trying to override ActiveRecord::Base#first, but Rails isn't too pleased with that. It yells at me saying ArgumentError: You tried to define a scope named "first" on the model "Item", but Active Record already defined a class method with the same name. Do I have to use a different method if I want to sort and have it sort

问题 I'm wanting to use UUIDs in an app I'm building and am running into a bit of a problem. Due to UUIDs (v4) not being sortable because they're randomly generated, I'm trying to override ActiveRecord::Base#first, but Rails isn't too pleased with that. It yells at me saying ArgumentError: You tried to define a scope named "first" on the model "Item", but Active Record already defined a class method with the same name. Do I have to use a different method if I want to sort and have it sort

问题 An Android app from my organization needs to assign each users an UUID(version 4) when they first launch the app, currently we're using Boost library 1.58.0 for this purpose, our Android app will use JNI to run the code below for generating UUIDv4: boost::uuids::basic_random_generator<boost::random::lagged_fibonacci44497> generator; generator(); //generating UUIDv4 The code worked fine for years, now we're deciding to replace it with an API in Java(UUID.randomUUID()). But we think it would be

问题 How can we generate unique id's between two JVMs running at the same time? I think UUID uuid = UUID.randomUUID(); or UID uid = new UID(); is not enough. 回答1: You can concat to UUID server ID so UUID will be unique in all servers 回答2: See UUID docs, you can follow the link to find the rfc4122 explaining how the UUID will be generated. The last 48 bits are concerning your question, the spacial unique node identifier confirming that this value will be a Universally Unique IDentifier . 4.1.2.

问题 How can we generate unique id's between two JVMs running at the same time? I think UUID uuid = UUID.randomUUID(); or UID uid = new UID(); is not enough. 回答1: You can concat to UUID server ID so UUID will be unique in all servers 回答2: See UUID docs, you can follow the link to find the rfc4122 explaining how the UUID will be generated. The last 48 bits are concerning your question, the spacial unique node identifier confirming that this value will be a Universally Unique IDentifier . 4.1.2.

问题 Inspired by the suggestion given here - JPA Entity class giving error with 2 @GeneratedValue fields, my question is the OPPOSITE of this - How to generate uuids without dashes I am using H2 DB and have this in my model: @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "id") private Long id; @Column(name = "useruuid") @GeneratedValue(generator = "uuid") @GenericGenerator(name = "uuid", strategy = "uuid4") private UUID userUUID; And in my controller it goes like this:

问题 I am wondering how to generate a GUID given an input string, such that the same input string results in the same GUID (sort of like an MD5 hash). The problem with MD5 hashes is they just guarantee low collision rate, rather than uniqueness. Instead I would like something like this: guid('v1.0.0') == 1231231231123123123112312312311231231231 guid('v1.0.1') == 6154716581615471658161547165816154716581 guid('v1.0.2') == 1883939319188393931918839393191883939319 How would you go about implementing

问题 I have the following controller: @Slf4j @RestController @RequestMapping("/v1") @Validated public class HighlightController { // ... @GetMapping("/highlights") public ResponseEntity<List<Highlight>> getHighlights( @RequestParam(required = false) UUID impersonateUserId ) { // ... Then I have the following controller exception handler: @Slf4j @ControllerAdvice public class GlobalExceptionHandler { //... @ExceptionHandler(value = IllegalArgumentException.class) public ResponseEntity<Object>