cassandra

问题 I wanted to know if there's a way to join two or more result sets into one. I actually need to execute more than one query and return just one result set. I can't use the UNION or the JOIN operators because I'm working with Cassandra (CQL) Thanks in advance ! 回答1: Framework like Playorm provide support for JOIN (INNER and LEFT JOINs)queries in Cassandra. http://buffalosw.com/wiki/Command-Line-Tool/ You may see more examples at: https://github.com/deanhiller/playorm/blob/master/src/test/java

问题 I am new to cassandra, As per my understanding depending on the configured partitioner(murmur3partitioner or randomaccess partitioner) there is a partitions limit per table. if we configure keyspace with murmur3partitioner which would enforce the partitions limit of 2^63 partitions per table. while inserting the row, if the new insertion tries to create new partition beyond the limit, the insertion would fail(means if I get unique combinations of row keys more than 2^63 per table). Can anyone

问题 I want to implement pagination on the UI, so I set fetchSize like this: boundStatement.setFetchSize(20) But the setFetchSize() is not honored. My table has 400 rows as of now and all 400 rows are retrieved. When I retrieve the next set of rows using rs.getExecutionInfo().getPagingState(); then the next 380 rows are retrieved. So the paging state is correctly set and retrieved, but why is the driver retreiving all 400 rows from the table and how can I avoid this or make it retrieve only 400

问题 cluster = Cluster.builder() .addContactPoint("localhost") .build(); Exception in thread "main" java.lang.NoClassDefFoundError: com/google/common/util/concurrent/AsyncFunction The only jars I have in my path are the 2 cassandra java driver jars cassandra-driver-core-2.1.10.3.jar and cassandra-driver-mapping-2.1.10.3.jar Thanks 回答1: The issue is with missing guava.jar. Adding this in the class path solved (this) issue. Overall issue is lack of suitable DataSatx documentaion 来源： https:/

问题 cluster = Cluster.builder() .addContactPoint("localhost") .build(); Exception in thread "main" java.lang.NoClassDefFoundError: com/google/common/util/concurrent/AsyncFunction The only jars I have in my path are the 2 cassandra java driver jars cassandra-driver-core-2.1.10.3.jar and cassandra-driver-mapping-2.1.10.3.jar Thanks 回答1: The issue is with missing guava.jar. Adding this in the class path solved (this) issue. Overall issue is lack of suitable DataSatx documentaion 来源： https:/

问题 After adding a pair of columns in schema, I want to select them via select * . Instead select * returns old set of columns and none new. By documentation recommendation, I use {prepare: true} to smooth JavaScript floats and Cassandra ints/bigints difference (I don't really need the prepared statement here really, it is just to resolve this ResponseError : Expected 4 or 0 byte int issue and I also don't want to bother myself with query hints ). So on first execution of select * I had 3 columns

问题 I have enabled ssl encryption in my cassandra node and I am trying to figure out how to connect to my node using cqlsh with ssl: When I run ./cqlsh --ssl I get the following error: Validation is enabled; SSL transport factory requires a valid certfile to be specified. Please provide path to the certfile in [ssl] section as 'certfile' option in /root/.cassandra/cqlshrc (or use [certfiles] section) or set SSL_CERTFILE environment variable. I followed the link on https://docs.datastax.com/en

问题 I have enabled ssl encryption in my cassandra node and I am trying to figure out how to connect to my node using cqlsh with ssl: When I run ./cqlsh --ssl I get the following error: Validation is enabled; SSL transport factory requires a valid certfile to be specified. Please provide path to the certfile in [ssl] section as 'certfile' option in /root/.cassandra/cqlshrc (or use [certfiles] section) or set SSL_CERTFILE environment variable. I followed the link on https://docs.datastax.com/en

问题 How to set Cassandra (>2.0) JVM heap size of 8GB? When I type in free -m it gives me the following. How can I set the Cassandra JVM heap size to 8GB? total used free shared buffers cached Mem: 16047 11336 4711 0 81 5814 -/+ buffers/cache: 5441 10606 Swap: 0 0 0 回答1: As stated in the Tuning Java resources section of the documentation: If you decide to change the Java heap sizing, both MAX_HEAP_SIZE and HEAP_NEWSIZE should should be set together in conf/cassandra-env.sh. Inside cassandra-env.sh

问题 i have problem with ordering data in cassandra Database . this is my table structure: CREATE TABLE posts ( id uuid, created_at timestamp, comment_enabled boolean, content text, enabled boolean, meta map<text, text>, post_type tinyint, summary text, title text, updated_at timestamp, url text, user_id uuid, PRIMARY KEY (id, created_at) ) WITH CLUSTERING ORDER BY (created_at DESC) and when i run this query , i got the following message: Query : select * from posts order by created_at desc;