cassandra-3.0

问题 I know, Cassandra generally converts all the column names into lowercase. Is there a performance impact in using the camelCase in column names in Cassandra? I used the double quote in columns and I am able to store the column names in the camelCase, like below CREATE TABLE test ( Foo int PRIMARY KEY, "Bar" int ); Will there be a performance impact in storing the column name with the double quotes? 回答1: I don't believe there's an impact. I would say that the case-insensitive nature of CQL only

问题 So this is driving me crazy. i tried querying one of my table in Cassandra and it showed query failure. i tried digging dip in to the reason behind it and found that it was because of tombstone. i changed GC_GRACE_SECONDS to Zero and triggered Compaction using nodetool, And when i queried again it worked fine. however on a subsequent calls query failed again with a same reason. i am using cassandra-nodejs driver. This is my data model. CREATE TABLE my_table ( firstname text, lastname text,

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 am working on SPARK-SQL 2.3.1 and I am trying to enable the hiveSupport for while creating a session as below .enableHiveSupport() .config("spark.sql.warehouse.dir", "c://tmp//hive") I ran below command C:\Software\hadoop\hadoop-2.7.1\bin>winutils.exe chmod 777 C:\tmp\hive While running my program getting: Caused by: java.lang.RuntimeException: java.lang.RuntimeException: The root scratch dir: /tmp/hive on HDFS should be writable. Current permissions are: rw-rw-rw- at org.apache.hadoop.hive

问题 I've noticed that relationships cannot be properly stored in C* due to its 100MB partition limit, denormalization doesn't help in this case and the fact that C* can have 2B cells per partition neither as those 2B cells of just Longs have 16GB ?!?!? Doesn't that cross 100MB partition size limit ? Which is what I don't understand in general, C* proclaims it can have 2B cells but a partition sizes should not cross 100MB ??? What is the idiomatic way to do this? People say that this an ideal use

问题 I have a brand new Windows 10 Home installation, with a brand-new installation of JDK 10.0.1 (which is what Oracle recommended when I went to the JDK download site.) I just now downloaded Cassandra 3.11.2, un-tar'd it, and put the bin directory on my classpath. When I attempt to start Cassandra using the cassandra -f command, I get this error: PS C:\javatools> cassandra -f *---------------------------------------------------------------------* *------------------------------------------------

问题 From How is data deleted? Cassandra allows you to set a default_time_to_live property for an entire table. Columns and rows marked with regular TTLs are processed as described above; but when a record exceeds the table-level TTL, Cassandra deletes it immediately, without tombstoning or compaction . This is also answered here If a table has default_time_to_live on it then rows that exceed this time limit are deleted immediately without tombstones being written . And commented in LastPickle's

问题 Can someone help me to store the current system date in cassandra date column in format yyyy-mm-dd using Java? I get exception while saving the java.sql.Date using MappingManager . My sample program is: Test.java import com.datastax.driver.mapping.annotations.Table; import java.sql.Date; @Table(keyspace = "testing", name = "test") public class Test { private String uid; private Date rece; public String getUid() { return uid; } public void setUid(String uid) { this.uid = uid; } public Date

问题 I have a Data model like below, CREATE TABLE appstat.nodedata ( nodeip text, timestamp timestamp, flashmode text, physicalusage int, readbw int, readiops int, totalcapacity int, writebw int, writeiops int, writelatency int, PRIMARY KEY (nodeip, timestamp) ) WITH CLUSTERING ORDER BY (timestamp DESC) where, nodeip - primary key and timestamp - clustering key (Sorted by descinding oder to get the latest), Sample data in this table, SELECT * from nodedata WHERE nodeip = '172.30.56.60' LIMIT 2;

问题 I see this error continuously in the debug.log in cassandra, WARN [SharedPool-Worker-2] 2018-05-16 08:33:48,585 BatchStatement.java:287 - Batch of prepared statements for [test, test1] is of size 6419, exceeding specified threshold of 5120 by 1299. In this where, 6419 - Input payload size (Batch) 5120 - Threshold size 1299 - Byte size above threshold value so as per this ticket in Cassandra, https://github.com/krasserm/akka-persistence-cassandra/issues/33 I see that it is due to the increase