nosql

问题 I get an exception when calling com.tinkerpop.blueprints.Edge.getLabel on some vertex edges : java.lang.IllegalStateException: Could not find type for id: 630 at com.google.common.base.Preconditions.checkState(Preconditions.java:200) at com.thinkaurelius.titan.graphdb.types.vertices.TitanTypeVertex.getName(TitanTypeVertex.java:30) at com.thinkaurelius.titan.graphdb.transaction.StandardTitanTx$VertexConstructor.get(StandardTitanTx.java:321) I can solve this issue by removing all vertex and

问题 My Compression strategy in Production was LZ4 Compression. But I modified it to Deflate For compression change, we had to use nodetool Upgradesstables to forcefully upgrade the compression strategy on all sstables But once upgradesstabloes command completed on all the 5 nodes in the cluster, My requests started to fail, both read and write The issue is traced to a specific node out of the 5 node cluster and to a spcific table on that node. My whole cluster has roughly same amount of data and

问题 I don't understand one thing about Cassandra. Say, I have similar website to Facebook, where people can share, like, comment, upload images and so on. Now, let's say, I want to get all of the things my friends did: Username1 liked you comment username 2 updated his profile picture And so on. So after a lot of reading, I guess I would need to do is create new Column Family for each single thing, for example: user_likes user_comments , user_shares . Basically, anything you can think off, and

问题 Using cassandra, I want to store 20 million+ of row key in column family. my question is: Is there a REAL performance difference between long and utf8 rowKey keys? any,row key storage size problem? my userkey look like this rowKey=>112512462152451 rowKey=>135431354354343 rowKey=>145646546546463 rowKey=>154354354354354 rowKey=>156454343435435 rowKey=>154435435435745 回答1: Cassandra stores all data on disk (including row key values) as a hex byte array. In terms of performance, the datatype of

问题 This is a continuation of the project outlined in this question. I have the following model: class Product { public string Id { get; set; } public string[] Specs { get; set; } public int CategoryId { get; set; } } The "Specs" array stores product specification name value pairs joined by a special character. For example if a product is colored blue the spec string would be "Color~Blue". Representing specs in this way allows querying for products having multiple spec values specified by a query

问题 So lets say I have a table with about 180 columns and 100 records. This table is backed up into temporary table and original one is removed. After this migration (change) is run on a pipeline which produces the same table. I want to compare the backed up table to the new one adn rows (records) with any difference to be moved to 3rd table (_result table) so I do: INSERT OVERWRITE TABLE zakj_customers.customers_detail_result SELECT acct_id, IF (a.title != b.title, 1, 0) title, IF (a.fname != b

问题 So lets say I have a table with about 180 columns and 100 records. This table is backed up into temporary table and original one is removed. After this migration (change) is run on a pipeline which produces the same table. I want to compare the backed up table to the new one adn rows (records) with any difference to be moved to 3rd table (_result table) so I do: INSERT OVERWRITE TABLE zakj_customers.customers_detail_result SELECT acct_id, IF (a.title != b.title, 1, 0) title, IF (a.fname != b

问题 I have two tables, and some fields between that tables has many-to-many relationships. How can i implement this feature in Amazon DynamoDB? 回答1: Quick answer: Either in your code or denormalize your tables (store redundant data). Denormalize; in otherwords, store redundant data in the central "join" table so you can get all the information you want by querying that one table. This is probably your best option, but you need to remember to update all relevant records in the central table when

问题 I've tried to figure out what will be the best use cases that suit for Amazon dynamoDB. When I googled most of the blogs says DyanmoDb will be used only for a large amount of data (BigData). I'm having a background of relational DB. NoSQL DB is new for me.So when I've tried to relate this to normal relation DB knowledge. Most of the concepts related to DynamoDb is to create a schema-less table with partition keys/sort keys. And try to query them based on the keys.Also, there is no such

问题 I'm looking for a common data access framework that will provide portability across various nosql databases like SimpleDB, Azure Tables, Cassandra, CouchDB, MongoDb, etc. I'm building an app and would like my customers to be able to use which ever nosql store they want. In a more relational scenario, I'd use Linq over nHibernate or Entity Framework, but I haven't found an equivalent framework for nosql databases. All I've found is database specific API's even though there seem to be