BigTable

所谓并行执行，是指能够将一个大型串行任务（任何DML，或者一般的DDL）物理地划分为多个较小的部分，这些较小的部分可以同时得到处理。 1 何时使用并行执行 并行执行本质上是一个 不可扩缩 的解决方案，设计为允许单个用户或每个特定SQL语句占用数据库的所有资源。如果某个特性允许一个人使用所有可用的资源，倘若再允许两个人使用这个特性，就会遇到明显的竞争问题。 在应用并行执行之前，需要保证以下两点成立： 必须有一个非常大的任务 ，如对50GB数据进行全面扫描。 必须有足够的可用资源 。在并行全面扫描50GB数据之前，你要确保有足够的空闲CPU（以容纳并行进程），还要有足够的I/O通道，等等。 2 并行查询 scott@ORCL>explain plan for 2 select count(status) from big_table; 已解释。 scott@ORCL>select * from table(dbms_xplan.display); PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------- -------------------------------------------------------------------------

I need a way to do key-value lookups across (potentially) hundreds of GB of data. Ideally something based on a distributed hashtable, that works nicely with Java. It should be fault-tolerant, and open source. The store should be persistent, but would ideally cache data in memory to speed things up. It should be able to support concurrent reads and writes from multiple machines (reads will be 100X more common though). Basically the purpose is to do a quick initial lookup of user metadata for a web-service. Can anyone recommend anything? You might want to check out Hazelcast . It is distributed

Sorry if this question is somewhat subjective. I am new to 'could store', 'distributed store' or some concepts like this. I really wonder what do they have in common and want to get an overview on all of them. What do I need to prepare if I want to write a product similar to this? The NoSQL Database site summarizes the concept like this: Next Generation Databases mostly address some of the points: being non-relational, distributed, open-source and horizontal scalable. The original intention has been modern web-scale databases. The movement began early 2009 and is growing rapidly. Often more

Duplicates Why should I use document based database instead of relational database? Pros/Cons of document based database vs relational database I don't know much about Google's Bigtable but am wondering what the difference between Google's Bigtable and relational databases like MySQL is. What are the limitations of both? tylerl Bigtable is Google's invention to deal with the massive amounts of information that the company regularly deals in. A Bigtable dataset can grow to immense size (many petabytes) with storage distributed across a large number of servers. The systems using Bigtable include

In BigTable/GFS and Cassandra terminology, what is the definition of a SSTable? Sorted Strings Table (borrowed from google) is a file of key/value string pairs, sorted by keys "An SSTable provides a persistent,ordered immutable map from keys to values, where both keys and values are arbitrary byte strings. Operations are provided to look up the value associated with a specified key, and to iterate over all key/value pairs in a specified key range. Internally, each SSTable contains a sequence of blocks (typically each block is 64KB in size, but this is configurable). A block index (stored at

How to put a spacing of colors in a table of xtable? I generate the tables with the following instructions: test.table<-xtable(summary(test),caption='test', floating = FALSE) align(test.table) <- "|c|l|" print(test.table,caption.placement='top') thanks for your answers 42- The html.table.attributes parameter needs a character vector of length equal to number of tables. This produces a bordered, centered table on a rather ugly yellow-orange background: data(tli) tli.table <- xtable(tli[1:20,]) digits(tli.table)[c(2,6)] <- 0 print(tli.table,type="html", html.table.attributes='border='1' align=

I am trying to use the bigtable emulator from gcloud beta emulators. I launch the emulator, grab the hostname (localhost) and port (in this instance 8885) gcloud beta emulators bigtable start Executing: /usr/local/Caskroom/google-cloud-sdk/latest/google-cloud-sdk/platform/bigtable-emulator/cbtemulator --host=localhost --port=8885 I am trying to connect to the emulator from a java test client, here is what I provide: Configuration conf = BigtableConfiguration.configure(projectId, instanceId); if(!Strings.isNullOrEmpty(host)){ conf.set(BigtableOptionsFactory.BIGTABLE_HOST_KEY, host); conf.set