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VirtualBox下保证Guest和Host之间时间同步以及虚拟机之间共享磁盘
今天在搭建RAC的时候一直找不到如何设置才能是的虚拟机跟真实机之间时间同步的问题，网上找了很多资料，但绝大多数都是关于VMWare的设定，而且还是要禁止同步的。 &nb...
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unusable index in oralce
今天在网上看到一篇帖子，说的是被置为unusable的索引在truncate相应表之后竟然有变回valid的状态，后来在11g里面试了下，仍然发生，以后遇到这种问题要小心了。具体过程如下：idx_test是表test上的普通索引...
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Key Compression of Index
What is Index Compression?Oracle introduced a compression option for indexes in Oracle 8.1. You can create an index as compressed, or rebuild it to compress it.--create index with compress keyword...
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Index Scan
索引分类： Full Index Scan数据的获取仅从索引中得到，结果集按序排列（每次得到叶块中的数据都是从branch遍历到leaf block得到，顺序是以引导列为基础进行排序），索引列部分或者全部存在于...
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NOTES on concepts ---Partitions
Each partition is an independent object withits own name and optionally its own storage characteristics.Benefits include:Increased availability： The query optimizer automatically r...
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NOTES on concepts ---Tables
1. Category1) Object tables2) Relational tablesHeap-organized table Index-organized tableExternal table A table is either permanent or temporary. A permanent t...
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NOTES on concepts ---schema objects
1. Object types1) table: store data in row2) index3) partition: pieces of large tables and indexes4) view5) sequence6) dimension:A dimens...
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index-organized table
B-tree index entries are usually quite small, because they only consist of the key valueand a ROWID. In index-organized tables, however, the B-tree index entries can be large,because they consist of t...
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concept---Index-Organized Table
1. OverviewA table stored in a variation of B-tree index structure.Each index entry in the B-tree also stores non-key column values. Thus, the index is the data, the data is the index....
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Configure OGG to maintain a standby database
1. Overview of a live standby configurationIn thisconfiguration, there is an inactive Oracle GoldenGate Extract groupand an inactive data pump on the live standby system. Both of those...
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Tips on GoldenGate
1. Oracle补全日志默认情况下redo日志中只记录rowid以及被修改的字段的信息。当GoldenGate还原该事务，是SQL层面根据唯一键值来定位记录，故需要将主键或其他字段信息附近到日志中。最小附加日志，是开启logmnr...
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Monitoring GoldenGate Processing
Overview monitoring toolsGGSCI information commands The ggserr.log file (error log)Process reportThe discard filesThe logs at operating-system levelUsing the information commands ...
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GoldenGate Architecture
Architecture1.Manager The GoldenGate Managerprocess is used to manage all of the GoldenGateprocesses and resources. A single Manager process runs on each server wher...
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GoldenGate安装、配置
Preinstall:1. Alter source database in archive mode( alter the target either if perform. a bidirectional replication ).2. Add supplemental log to the source database.da...
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SQL语句中SELECT语句的执行顺序
select语句执行的逻辑处理顺序：(8)SELECT(9)DISTINCT(11) <TOP_specification> <select_list>(1) FROM <left_table>(3) <join_type> JOIN <right_table>(2) ON <join_condition>(4) WHERE <wher...
