笔者是MongoDB用户,也使用过Redis。关系型数据库使用过MySQL与Oracle,对两者的区别有一定的体会。Mongo和Redis的操作都非常简单,速度很快,很多用SQL需要很多条语句的操作在NoSQL数据库中都是2句以内完成。另外NoSQL配置cluster也很容易,且可以随时更改partition和replication的数量,Mongo的新版
In the 1990's, vertically integrated applications gave way to client-server architectures, and more recently, client-server architectures gave way to three-tier web application architectures. In parallel, the demands of web-scale services added very low latency real-time access as well as offline ...
Enables developers to analyze NoSQL data natively, including cross-collection queries and parallel scalability, without having to move the data. Rich indexing into JSON documents Create an index on any JSON field at any depth in the document hierarchy, thus improving query performance. ...
Media Recovery failed with error 10562 ORA-283 signalled during: ALTER DATABASE RECOVER datafile 2 ... 发现2号数据文件异常,报ORA-600 6101和ORA-600 kdxlin:psno out of range错误,出现该错误的原因主要是由于数据文件的bock和redo中信息不匹配导致,对于这种情况,我这边选择使用Oracle Recovery Tools工具进...
3.4.157 –xopenmp[={parallel|noopt|none}] 3.4.158 –xpad 3.4.159 –xpagesize=size 3.4.160 –xpagesize_heap=size 3.4.161 –xpagesize_stack=size 3.4.162 -xpatchpadding[={fix|patch|size}] 3.4.163 –xpec[={yes|no}] 3.4.164 –xpg 3.4.165 –xpp={fpp|cpp} 3.4.166 –xprefetch...
DB:oracle 10.2.0.4 问题来源于一条SQL跑的很慢,原因在于某个字段存在NULL,走不了索引。后来在该字段上建立了函数索引 create index I_IND_BATCHCODE on TS_BATCHCODE(VBATCHCODE,0) parallel nologging; alter index I_IND_BATCHCODE noparallel;
Action:Do not set the OCI_ATTR_DIRPATH_NO_INDEX_ERRORS to TRUE for direct path parallel loads. : ORA-39819:在直接路径并行加载中无法将OCI_ATTR_DIRPATH_NO_INDEX_ERRORS属性设置为真。 官方解释 常见案例 一般处理方法及步骤 1.确保与相应的表有关的索引都处于可用状态 ...
关系型数据库使用过MySQL与Oracle,对两者的区别有一定的体会。Mongo和Redis的操作都非常简单,速度很快,很多用SQL需要很多条语句的操作在NoSQL数据库中都是2句以内完成。另外NoSQL配置cluster也很容易,且可以随时更改partition和replication的数量,Mongo的新版本还内置...
log file parallel write 和log file sync这两个等待事件关系密切,很多人对这两个等待事件有一些误解,我们先来看看Oracle官方文档的解释: log file...这样的论断,其实我们仔细看看oracle官方文档的定义,log file sync是要从写log buffer算起的,其实oracle用的是group commit 来提高写redo的效率,也叫 完全揭秘log ...
Isolationmeans no two transactions mingle or interfere with each other. You get the same result when the two transactions are executed in sequence or executed in parallel. Durabilitymeans the changes of a transaction are saved and the changes survive any type of failure (network, disk, CPU or ...