This chapter focuses on advanced grouping, windowed aggregation, and Online Analytic Processing (OLAP) in SQL. As OLAP is concerned with summarizing and reporting data, the schema designs and common operations are very different from the usual SQL queries. Until recent changes in SQL, OLAP queries...
ClickHouse is an open source column-oriented database management system capableofreal time generationofanalytical data reports usingSQLqueries. ClickHouse最大的特点就是快,快,快,重要的话说三遍! ClickHouse是近年来备受关注的开源列式数据库,主要用于数据分析(OLAP)领域。目前国内社区火热,各个大厂纷纷跟进大规模...
summary_queries.sql 注:这些文件包含本教程中使用的完整的 OLAP 多维数据集和 SQL 汇总查询。 3. 能够访问属于 Oracle OLAP 11g 示例模式程序包的 OLAP 数据模型。您可以: A. 成功完成构建 OLAP11g 多维数据集教程,或者 B. 使用安装 Oracle OLAP 11g 示例模式中的说明安装 OLAPTRAIN 示例模式和 SALESTRACK 分...
Presto is an open source distributed SQL query engine for running interactive analytic queries against data sources of all sizes ranging from gigabytes to petabytes.Presto allows querying data where it lives, including Hive, Cassandra, relational databases or even proprietary data stores. A single Pres...
关于向量化或者codegen,孰优孰劣,论文《Everything You Always Wanted to Know About Compiled and Vectorized Queries But Were Afraid to Ask》进行了深入的对比。二者也可以融合,通过codegen生成向量化执行代码,另外也不一定做wholestage codegen,和解释执行也可以一起配合。
ClickHouse是Yandex于2016年开源的列式存储数据库(DBMS),主要用于在线分析处理查询(OLAP),能够使用SQL查询实时生成分析数据报告. clickhouse优势: 与Hadoop、Spark这些巨无霸组件相比,ClickHouse很轻量级,其特点: 1.列式存储数据库,数据压缩 2.关系型、支持SQ
SQL语言是OLAP的标配,一个完整的SQL查询步骤包括1)SQL词法解析,语法解析,2)形成抽象语法树(AST),3)校验检查,4)AST转成关系代数表达式(relational algebra),5)根据关系代数表达式生成执行计划,先生成逻辑执行计划(logical plan),6)经过优化器生成最优的执行计划,7)根据执行计划生成物理执行计划(physical plan),8)最...
关于向量化或者codegen,孰优孰劣,论文Everything You Always Wanted to Know About Compiled and Vectorized Queries But Were Afraid to Ask [11]进行了深入的对比。二者也可以融合,通过codegen生成向量化执行代码,另外也不一定做wholestage codegen,和解释执行也可以一起配合。
Presto is an open source distributed SQL query engine for running interactive analytic queries against data sources of all sizes ranging from gigabytes to petabytes. Presto allows querying data where it lives, including Hive, Cassandra, relational databases or even proprietary data stores. A single Pr...
long_query_time 指定记录慢查询日志SQL执行时间得伐值(单位:秒,默认10秒) log_queries_not_using_indexes 是否记录未使用索引的SQL log_output 日志存放的地方【TABLE】【FILE】【FILE,TABLE】 配置了慢查询后,它会记录符合条件的SQL 包括: 查询语句