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Greenplum数据库基础培训new教程.ppt

发布:2017-05-04约1.46万字共99页下载文档
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Greenplum 数据库基础培训;Greenplum数据库;S1002 Network Configuration;Greenplum 基本体系架构;客户端接口和程序;Master Host; 每段(Segment)存放一部分用户数据 一个系统可以有多段 用户不能直接存取访问 所有对段的访问都经过Master 数据库监听进程(postgres)监听来自Master的连接; Greenplum数据库之间的连接层 进程间协调和管理 基于千兆以太网架构 属于系统内部私网配置 支持两种协议:TCP or UDP;Greenplum 高可用性体系架构;Standby 节点用于当 Master 节点损坏时提供 Master 服务 Standby 实时与 Master 节点的 Catalog 和事务日志保持同步;每个Segment的数据冗余存放在另一个Segment上,数据实时同步 当Primary Segment失败时,Mirror Segment将自动提供服务 Primary Segment恢复正常后,使用gprecoverseg –F 同步数据。; Hash分布 CREATE TABLE … DISTRIBUTED BY (column [,…]) 同样数值的内容被分配到同一个Segment上 循环分布 CREATE TABLE … DISTRIBUTED RANDOMLY 具有同样数值的行内容并不一定在同一个Segment上;查询命令的执行;查询命令的执行;SQL查询处理机制;SELECT customer, amount FROM sales JOIN customer USING (cust_id) WHERE date;表分区的概念;Segment 1A ;;表分区示意图;压缩存储;行列存储;外部表加载;基于外部表的高速数据加载;外部表加载的特征;Load good rows and catch poorly formatted rows, such as: rows with missing or extra attributes rows with attributes of the wrong data type rows with invalid client encoding sequences Does not apply to constraint errors: PRIMARY KEY, NOT NULL, CHECK or UNIQUE constraints Optional error handling clause for external tables: [LOG ERRORS INTO error_table] SEGMENT REJECT LIMIT count [ROWS | PERCENT] ( PERCENT based on gp_reject_percent_threshold parameter ) Example CREATE EXTERNAL TABLE ext_customer (id int, name text, sponsor text) LOCATION ( gpfdist://filehost:8081/*.txt ) FORMAT TEXT ( DELIMITER | NULL ) LOG ERRORS INTO err_customer SEGMENT REJECT LIMIT 5 ROWS; ; Data resides outside the database No database statistics for external table data Not meant for frequent or ad-hoc access Can manually set rough statistics in pg_class: UPDATE pg_class SET reltuples=400000, relpages=400 WHERE relname=myexttable; ; PostgreSQL command Support loading and unloading Optimized for loading a large number of rows Loads all rows in one command (not parallel) Loads data from a file or from standard input Supports error handling as does external tables EX
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