distributed-database

Why secondary indexes are less efficient in Cassandra?

由 柔情痞子 提交于 2021-01-24 07:06:08
问题 I read in Cassandra documentation that creating secondary index is less efficient as because in worst case it need to touch all nodes in order to find out the data of that non-key column. But my doubt is even if we do not create secondary index, then also it will have to touch all nodes (in worst case) and find out where that particular row with this non-key column value resides. Note: Yeah, I understand that it is possible that if the cardinality is high then the secondary index will contain

How to shard only specific tables using vitess

由 混江龙づ霸主 提交于 2020-01-24 15:04:42
问题 I have created an unsharded keyspace with three tables. Now I would like to shard my keyspace for first two tables but don't want to shard the third table. How can this be done? Vitess documentation does not contain any info or example regarding this. Please help. Thanks! 回答1: Vertical sharding in vitess is similar to horizontal sharding. You should use the vtworker VerticalSplitClone command instead of SplitClone. We plan to fix the documentation to explain this, hopefully soon. 来源： https:/

cassandra getendpoints with partition key has space

由 我们两清 提交于 2019-12-25 15:02:39
问题 my partition keys are id(int) and name(text). Below command works fine until there is no space in name(text). nodetool getendpoints test testtable2 1:aaa; if am using nodetool getendpoints test testtable2 3:aac cc; it throws an error as : nodetool: getendpoints requires keyspace, table and partition key arguments See 'nodetool help' or 'nodetool help '. i got token by executing SELECT id,name, token(id,name) FROM test.testtable2 where name='aac cc'AND id=3; and tried to search nodetool

Theoretical results of consensus protocol in primary-backup distributed system

由 流过昼夜 提交于 2019-12-23 03:12:33
问题 I am picking up knowledge of consensus protocols in a distributed system. Such a distributed system does primary-backup on databases. I learned that "every consensus protocol can loop forever." from Leader election for paxos-based replicated key value store Where is the information source of "every consensus protocol can loop forever"? Status update: question answered. The same information source was provided by rystsov and another person of another post. Could more theoretical results and

What node does Cassandra store data on?

由 余生颓废 提交于 2019-12-19 20:43:42
问题 Is there a command or any way at all to know what data is stored on what nodes of Cassandra? Im pretty new to Cassandra and haven't had much luck googling this question. Thanks! 回答1: You can get Cassandra to tell you which node(s) a particular key is on with nodetool getendpoints. $ nodetool getendpoints mykeyspace tbl '8546200' 192.168.73.188 192.168.73.190 I don't know if that's what you're looking for or not. AFAIK there isn't a way to flat-out query the responsible nodes for all rows in a

Creating a database in Orientdb in distributed mode

由 南楼画角 提交于 2019-12-11 12:30:26
问题 Our system creates OrientDB databases programmatically and uses one database for each customer (before anyone jump on dismissing this design, the reasons are security, possibility to move certain customer/data between datacenters/regions and the possibility to relocation to on-premise). This works great in OrientDB in single mode. However, when the database is setup in distributed mode (3 servers, on amazon). The behaviour is, to put it mildly, weird. I know the docs doesn't say anything

Looking for distributed, in-memory Graph DB [closed]

由 青春壹個敷衍的年華 提交于 2019-12-05 02:27:15
问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 4 years ago . Is there a database which will satisfy all (or at least most) of this requirements? Graph oriented - optimized for storing graphs and traversal(e.g HyperGraphDB, Neo4j) Running in memory, but having a persisted storage (e.g. Redis) Distributed (e.g. membase) Had .NET adapter (TCP/IP, not HTTP REST) Or am I

Looking for distributed, in-memory Graph DB [closed]

由 一笑奈何 提交于 2019-12-03 16:32:39
Closed. This question is off-topic. It is not currently accepting answers. Learn more . Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 4 years ago . Is there a database which will satisfy all (or at least most) of this requirements? Graph oriented - optimized for storing graphs and traversal(e.g HyperGraphDB, Neo4j) Running in memory, but having a persisted storage (e.g. Redis) Distributed (e.g. membase) Had .NET adapter (TCP/IP, not HTTP REST) Or am I asking too much? Thanks in advance. It seems hard to find .NET based one... I hope this might

Need a distributed key-value lookup system

由 不羁岁月 提交于 2019-12-03 05:55:01
问题 I need a way to do key-value lookups across (potentially) hundreds of GB of data. Ideally something based on a distributed hashtable, that works nicely with Java. It should be fault-tolerant, and open source. The store should be persistent, but would ideally cache data in memory to speed things up. It should be able to support concurrent reads and writes from multiple machines (reads will be 100X more common though). Basically the purpose is to do a quick initial lookup of user metadata for a

Need a distributed key-value lookup system

由 雨燕双飞 提交于 2019-12-02 20:35:06
I need a way to do key-value lookups across (potentially) hundreds of GB of data. Ideally something based on a distributed hashtable, that works nicely with Java. It should be fault-tolerant, and open source. The store should be persistent, but would ideally cache data in memory to speed things up. It should be able to support concurrent reads and writes from multiple machines (reads will be 100X more common though). Basically the purpose is to do a quick initial lookup of user metadata for a web-service. Can anyone recommend anything? You might want to check out Hazelcast . It is distributed
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