常见的关系型数据库据悉，阿里云数据库MongoDB版采用了三节点副本集高可用架构，100%兼容MongoDB协议
无论更新还是插入数据，数据都需要首先在内存中的Buffer Pool驻留，然后通过CheckPoint和Lazy Writer等过程将内存中的数据持久化到磁盘
NoSQL 兼容基于 SQL 支持 JSON、XML 等非结构化数据类型
eXtremeDB的微秒级查询性能符合了这个要求
中间我们提供了一个分布式文件访问接口，供上层计算节点调用
执行导入时，Sqoop可以写入HDFS、Hive和HBase，对于输出，它可以执行相反操作
该文件的内容如下： ## $Header: init.ora 1.2 94/10/18 16:12:36 gdudey Osd $ init.ora Copyr (c) 1991 Oracle# ############################################################################## # Example INIT.ORA file # # This file is provided by Oracle Corporation to help you customize # your RDBMS installation for your site. Important system parameters# are discussed, and example settings given.## Some parameter settings are generic to any size installation. # For parameters that require different values in different size# installations, three scenarios have been provided: SMALL, MEDIUM# and LARGE. Any parameter that needs to be tuned according to# installation size will have three settings, each one commented # according to installation size. # # Use the following table to approximate the SGA size needed for the # three scenarious provided in this file:## -------Installation/Database Size------# SMALL MEDIUM LARGE # Block 2K 4500K 6800K 17000K # Size 4K 5500K 8800K 21000K # # To set up a database that multiple instances will be using, place# all instance-specific parameters in one file, and then have all# of these files point to a master file using the IFILE command.# This way, when you change a public# parameter, it will automatically change on all instances. This is# necessary, since all instances must run with the same value for many# parameters. For example, if you choose to use private rollback segments, # these must be specified in different files, but since all gc_* # parameters must be the same on all instances, they should be in one file.# # INSTRUCTIONS: Edit this file and the other INIT files it calls for # your site, either by using the values provided here or by providing # your own. Then place an IFILE= line into each instance-specific # INIT file that points at this file. ############################################################################### db_name = oracle db_files = 20 control_files = C:ORAWIN95DATABASEctl1orcl.ora compatible = 7.3.0.0.0 db_file_multiblock_read_count = 8 ? # INITIAL# db_file_multiblock_read_count = 8 # SMALL# db_file_multiblock_read_count = 16 # MEDIUM# db_file_multiblock_read_count = 32 # LARGE db_block_buffers = 200 # INITIAL# db_block_buffers = 200# SMALL# db_block_buffers = 550 # MEDIUM # db_block_buffers = 3200 # LARGE shared_pool_size = 3500000 # INITIAL# shared_pool_size = 3500000 # SMALL # shared_pool_size = 6000000 # MEDIUM# shared_pool_size = 9000000 # LARGE log_checkpoint_interval = 10000processes = 50 # INITIAL # processes = 50 # SMALL # processes = 100 # MEDIUM # processes = 200 # LARGE dml_locks = 100 # INITIAL# dml_locks = 100 # SMALL # dml_locks = 200 # MEDIUM # dml_locks = 500 # LARGElog_buffer = 8192 # INITIAL# log_buffer = 8192 # SMALL# log_buffer = 32768 # MEDIUM # log_buffer = 163840 # LARGEsequence_cache_entries = 10 # INITIAL# sequence_cache_entries = 10 # SMALL # sequence_cache_entries = 30 # MEDIUM# sequence_cache_entries = 100# LARGEsequence_cache_hash_buckets = 10 # INITIAL# sequence_cache_hash_buckets = 10 # SMALL# sequence_cache_hash_buckets = 23 # MEDIUM# sequence_cache_hash_buckets = 89 # LARGE# audit_trail = true # if you want auditing# timed_statistics = true # if you want timed statisticsmax_dump_file_size = 10240 # limit trace file size to 5 Meg each# log_archive_start = true # if you want automatic archivinglog_archive_dest=%ORACLE_HOME%DATABASEARCHIVE# define directories to store trace and alert files background_dump_dest=%RDBMS73% raceuser_dump_dest=%RDBMS73% racedb_block_size = 2048 snapshot_refresh_processes = 1 remote_login_passwordfile = shared 可以修改该文件的db_file_multiblock_read_count，db_block_buffers，shared_pool_size，processes ，log_buffer，sequence_cache_entries，sequence_cache_hash_buckets等项（文件中均有提示），根据需要和系统使用的数据库服务器的特点适当改大数值，可以提高查询统计速度
这里简单就这些话题，做一些简明的介绍
但对于安全性要求比较高的客户来说，这种方式不太适用，对这样的客户，我们会在企业内部提供服务，这就是我们所说的局限性
因此，请在安装 VMM 服务器之前慎重考虑默认库共享的位置
要防止因为权限设置不当而导致信息泄露，从而使非法人士有机可乘，为他们破获数据库的正常运行提供方便
下面就有三种： WHERE TO_DAYS(date_col) - TO_DAYS(CURDATE()) < cutoff WHERE TO_DAYS(date_col) < cutoff + TO_DAYS(CURDATE()) WHERE date_col = ’Mac’ AND last_name < ’Mad’ 这种优化不能应用于使用了REGEXP操作符的模式匹配
队列的影响反映在每次读取或写入的磁盘秒数变高
[参考价格] 11286元[商家名称] 北京晨隆科技有限公司[联系方式] 13911353600? 010-62115309[联 系 人] 陈小姐[联系地址] 北京市海淀区中关村东路123号都市网景B座[报价查询] 甲骨文 Oracle Standard Edition One"
同时AS5600中高端存储优异的扩展性，也满足了平台后续功能的扩展需求，以及实现两地三中心容灾
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搜索效率的高低取决于数据库的性能和SQL语句的效率
找到适合自己企业的技术，用最合理的方式进行解决，不管是关系型还是非关系型，这才是最完美的海量数据解决方案
