cassandra db use cases

Although the size of the community is a less precise issue, at least 3,000 companies are using Cassandra in the production process. Over the past few months, we have learned more about applications that use Cassandra, and have come up with an attractive pattern in which more than 80% use

-cassandra-a The following result is displayed: YCSB Client 0.1Command line: -db com.yahoo.ycsb.db.CassandraClient10 -P workloads/workloada -p hosts=localhost -p columnfamily=data -load[OVERALL], RunTime(ms), 2287.0[OVERALL], Throughput(ops/sec), 437.25404459991256[INSERT], Operations, 1000[INSERT], AverageLatency(us), 1670.687[INSERT], MinLatency(us), 476[INSERT], MaxLatency(us), 280228[INSERT], 95thPerce

differences between APIs, it is difficult to provide a unified search and query interface for events and metrics. This is why we finally decided to write our own TSDB and store metrics through Casandra and Elasticsearch. Specifically, we store time/value pairs in Cassandra, store metadata in Elasticsearch, and have a query and management layer at the top. In this way, events and metrics can be searched and queried in Elasticsearch. Stream processing

1, Cassandra PreparationStart Cqlsh,cqlsh_host=172.16.163.131 Bin/cqlshCqlsh>create keyspace productlogs with REPLICATION = {' class ': ' Org.apache.cassandra.locator.SimpleStrategy ', ' Replication_factor ': ' 2 ' } cqlsh>CREATE TABLE productlogs.logs ( IDs uuid, app_name text, App_version text, city text, client_time timestamp, country text, created_at timestamp, int , device_id text ,int, modle_name text, Provin

Oracle Data Pump (Data Dump) often encounters some strange error cases during use. Oracle Data Pump (Data Dump) often encounters some strange error cases during use. The following summarizes some problems encountered during the use of Data pump (Data Dump) and their solution

There are a number of bizarre error cases encountered in the use of Oracle data pumps, which summarize some of the problems and solutions that you have encountered while using the data pump. Are the problems encountered in the use of the process, and then encountered the data pump (database Dump) error cases, will be s

we use MySQL user-defined session variables to solve the above problems. 1 public static function incCounter($uid, $aid, $status) {2 $db = Comm_Db::d(Comm_Db::DB_BASIC);3 $sql = "UPDATE ". self::table($aid) ." SET `ctn_counter`=@ctn_counter:=`ctn_counter`+1 WHERE `uid` = ? AND `aid` = ? AND `status` = ?";4 $db->execute($sql, array($uid, $aid, $status

configuration item just fine' Mdm.admin.configs ' = [ ' menutable ' = ' dbname2.menu ', //' usertable ' = ' dbname2.user ', ], > Note, why is this configuration item usertable shielded, this depends on the individual configuration, open file vendor\mdmsoft\yii2-admin\components\configs.php file, see if there are usertable Property, if there is, you need to configure here, if not, you configure the trial report without error 650) this.width=650; "Src=" Http://img.baidu.com/hi/jx2/j_0067.gif "

‘mdm.admin.configs‘ => [ ‘menuTable‘ => ‘dbname2.menu‘, // ‘userTable‘ => ‘dbname2.user‘, ], Notice, above this why configuration item usertable block, this depends on personal configuration, open file Vendor\mdmsoft\yii2-admin\components\ configs.php file, see if there is no usertable property, if there is, you need to configure here, if not, you configure the trial report no errorOne more step, the last and last step, is also an example of the explanation oh.For example, if we

.menu ',//' usertable ' = ' dbname2.user ',],Notice, above this why configuration item usertable shielding, this depends on personal configuration, open file vendor\mdmsoft\yii2-admin\components\Configs.php file, see userTable If there is no attribute, if there is, here need to configure, if not, you configure trial report not error 650) this.width=650; " Src= "Http://img.baidu.com/hi/jx2/j_0067.gif" style= "border:0px;vertical-align:middle;line-height:1.42857; alt=" J_0067.gif "/>One more step,

Database Transaction Processing #You can use the transaction method to perform a set of database transaction operations:Db::Transaction(function(){Db::Table(' Users ')->update ([ ' votes ' => 1]) ; db::table ( ' posts ' ->delete (;} Note: transaction any exception thrown in the closure causes the transaction to be automatically rolled back.

All calls to Nodejs are almost completely asynchronous, and all IO operations are known by callback functions. If an asynchronous call relies on another asynchronous call, it is possible to fall into the legendary callback hell if there is no promise.Bluebird implements the transformation of asynchronous callbacks into chained notation, and extends the APIs such as catch, finally, bind, and so on, which can help us focus on the error of each query.The information about promise and Bluebird found

), this will appear our table.* The above error is largely due to the fact that I did not rewrite the Onmodelcreating class in EF, and the problem with many of my previous creation of multiple tables was caused by this.below is a code in the data context public class Blogdbcontent:dbcontext, IDisposable {public blogdbcontent (): Base ("Name=blogsen Tities ") {} public dbsetConnection string for database Attachment:Fluent API ReferenceHttp://www.cnblogs.com/oppoic/p/ef_one-to-one_one