MongoDB

1. Optimize Pre-readingOptimize IO performance by using the Linux Blockdev command to set the pre-read size to smaller and reduce the unused data consumption in memoryThe RA represents the read-ahead size (sector), the recommended value is 16 to 32,

Today intends to integrate the MongoDB driver in my COF framework, which is really simple to work, because basically just the encapsulation of PymongoDatabase integration is similar, the point to consider is nothing more than the following:1. Naming2

After the successful start of MongoDB, and then open a command line window input MONGO, you can do some of the database operations.Enter help to see the basic Operations Command:Show DBS: Display Database listShow Collections: Displays a collection

Query.all ("name", "a", "B");//match array with multiple elementsQuery.and (Query.eq ("name", "a"), Query.eq ("title", "T"));//satisfy multiple conditions at the same timeQuery.eq ("name", "a");//equalsQuery.exists ("type", true);//Determine if key

Dynamic Registration listener SQL> select * from v$version where rownum=1;BANNER--------------------------------------------------------------------------------Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - ProductionSQL> !cat

Common Redis commands 1 Create-store or not-View-delete Set name maojun; exists name; get name; del name; 2. serialization record Set name maojun; exists name; dump name; the client is logged out, and exists name and name still exist. 3. Set the

Troubleshooting of FatalNIconnecterror12170. Check the database alarm log and find the error: Fatal NI connect error 12170.   The alarm log is as follows: **************************************** ******************************* Fatal NI connect

Data cleansing Note: Generation of primary key class ID Fields   Background] After data is extracted from the source end and inserted to the target end, a primary key ID field needs to be created.   [Solution] Method 1: Use the sys_guid () function

Use CodeFirst for dynamic database creation In the project ITOO3.0, a technical point is to dynamically create databases and tables. After a simple explanation, we will dynamically create a complete set of ITOO backend databases for a cloud platform

Expdp background View Today, after executing the data import command expdp, we found that there was less than one parameter. Press CTRL + C. Who can perform this operation only on the surface of cancel? In fact, the background is still

MongoDB basic (9) sharding Sharding stores data on multiple servers. Mongodb uses sharding to support deployment of very large datasets and high throughput operations. The capabilities of a single server are limited in various aspects, such as CPU,

AerospikeC client manual --- shared memoryZookeeperIn shared memory, each client instance runs an additional cluster server thread and periodically polls each server node of the cluster to get the cluster status. In a single process/multi-thread

Troubleshoot and solve a deadlockThis is a sad reminder. I remember last week's busy schedule. The goal is to modify some bugs in the code left by another team. This project is used for OLAP analysis, the Logic Server is mainly responsible for

Differences between truncate and delete Truncate table players; equivalent to delete from players; or delete players. * from players; 1. truncate is fast. If the rollback command is available, delete will be revoked, but truncate will not. 2.

Thoughts on data operation report system Purpose: Data indicators are the pulse of the product. Managers can understand the Product Operation overview by feeling the pulse changes. Fragment Tracking: The ultimate goal of all tracking points is

Solutions to common MongoDB errors After MongoDB was installed today, the service cannot be started this morning. The following error occurs: Error: Error 2: the specified file cannot be found. Thinking process: During the test yesterday, I

Set STATISTICS_LEVEL = BASIC to disable database features SetSTATISTICS_LEVEL =BASIC disables the features of oracle. Automatic Workload Repository (AWR) Snapshots Automatic Database Diagnostic Monitor (ADDM) All server-generated alerts

Manual and automatic start of multiple oracle instancesStart two instances manuallySu-oracleLsnrctl start-- Assume that one instance is itsm and the other is test.Export ORACLE_SID = itsmSqlplus/as sysdbaStartupQuitExport ORACLE_SID = testSqlplus/as

Mybatis single parameter if judgment (for exception: There is no getter for property ..) We all know that mybatis can be directly used for parameter determination. As shown in the following figure: 1. General Code   update t_test_l

Database Design of Customer Management System The Database Design of the customer management system is developed using the SQL Server 2008 database. The customer management system (Customermanagement) contains a total of seven tables, which are