timeuuid

How to generate unique id

由 雨燕双飞 提交于 2021-02-05 08:25:49
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.

How to generate unique id

由 試著忘記壹切 提交于 2021-02-05 08:25:10
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.

how do i get the date/time back from a UUID type 1

由 时间秒杀一切 提交于 2020-07-09 14:45:21
问题 I have included the following UUID library compile group: 'com.fasterxml.uuid', name: 'java-uuid-generator', version: '3.1.5' in my build. i have some code like this NoArgGenerator timeBasedGenerator = Generators.timeBasedGenerator() UUID tuid = timeBasedGenerator.generate() Timestamp timestamp = new Timestamp ((tuid.timestamp()/1000) as Long) Date dateTime = new Date (timestamp.getTime()) however when itry and look at the date its nothing like what it should be so for example i get 'uid

how do i get the date/time back from a UUID type 1

由 ε祈祈猫儿з 提交于 2020-07-09 14:42:13
问题 I have included the following UUID library compile group: 'com.fasterxml.uuid', name: 'java-uuid-generator', version: '3.1.5' in my build. i have some code like this NoArgGenerator timeBasedGenerator = Generators.timeBasedGenerator() UUID tuid = timeBasedGenerator.generate() Timestamp timestamp = new Timestamp ((tuid.timestamp()/1000) as Long) Date dateTime = new Date (timestamp.getTime()) however when itry and look at the date its nothing like what it should be so for example i get 'uid

Cassandra: change type from UUID to TIMEUUID

由 岁酱吖の 提交于 2019-12-13 01:05:58
问题 I'm trying to change the type of a column from UUID to TIMEUUID, but I'm unable to do so. ALTER TABLE Person ALTER KEY TYPE timeuuid; Error: Bad Request: Cannot change key from type uuid to type timeuuid: types are incompatible. Any idea on how to achieve this without losing the data from the column family? 回答1: It is not allowed. This is because TimeUUIDs have a different sorting pattern than regular UUIDs so Cassandra does not allow this. If you don't care about Columns being sorted by time

In Cassandra terminology, what is TimeUUID?

由 做~自己de王妃 提交于 2019-12-03 11:00:44
问题 In Cassandra terminology, what is TimeUUID and when is it used? 回答1: TimeUUID is one of six concrete implementations of the abstract class AbstractType. For ColumnFamilies you have the possiblity to specify an attribute called CompareWith. (SuperColumns have a similar CompareSubcolumnsWith attribute). Valid values for this attribute are classes that implements the abstract class AbstractType (eg. TimeUUID). The CompareWith attribute tells Cassandra how to sort the columns for slicing

Cassandra TimeUUID flood file descriptor when use uuid in default

由 大憨熊 提交于 2019-12-02 09:25:30
问题 I have Cassandra model as import uuid from cassandra.cqlengine import columns from cassandra.cqlengine.models import Model class MyModel(Model): ... ... created_at = columns.TimeUUID(primary_key=True, clustering_order='DESC', default=uuid.uuid1) ... ... Recentrly app hit the uuid1 creation doesn't close files - hits file descriptor limit. I try to find the solution, but seems what options I think might be not work Replace uuid1 in default with uuid4 , but TimeUUID need time part in it, and

Cassandra TimeUUID flood file descriptor when use uuid in default

由 杀马特。学长 韩版系。学妹 提交于 2019-12-02 06:41:07
I have Cassandra model as import uuid from cassandra.cqlengine import columns from cassandra.cqlengine.models import Model class MyModel(Model): ... ... created_at = columns.TimeUUID(primary_key=True, clustering_order='DESC', default=uuid.uuid1) ... ... Recentrly app hit the uuid1 creation doesn't close files - hits file descriptor limit . I try to find the solution, but seems what options I think might be not work Replace uuid1 in default with uuid4 , but TimeUUID need time part in it, and only uuid1 provide that. Relace uuid1 with cassandra.util.uuid_from_time(time.time()) , when check the

Cassandra UUID vs TimeUUID benefits and disadvantages

由 不想你离开。 提交于 2019-11-28 04:39:21
Given that TimeUUID handily allows you to use now() in CQL, are there any reasons you wouldn't just go ahead and always use TimeUUID instead of plain old UUID? UUID and TIMEUUID are stored the same way in Cassandra, and they only really represent two different sorting implementations. TIMEUUID columns are sorted by their time components first, and then by their raw bytes, whereas UUID columns are sorted by their version first, then if both are version 1 by their time component, and finally by their raw bytes. Curiosly the time component sorting implementations are duplicated between UUIDType

Cassandra UUID vs TimeUUID benefits and disadvantages

由 陌路散爱 提交于 2019-11-27 04:18:13
问题 Given that TimeUUID handily allows you to use now() in CQL, are there any reasons you wouldn't just go ahead and always use TimeUUID instead of plain old UUID? 回答1: UUID and TIMEUUID are stored the same way in Cassandra, and they only really represent two different sorting implementations. TIMEUUID columns are sorted by their time components first, and then by their raw bytes, whereas UUID columns are sorted by their version first, then if both are version 1 by their time component, and
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