Teradata - CASE & COALESCE Teradata - Primary Index Teradata - Joins Teradata - SubQueries Teradata Advanced Teradata - Table Types Teradata - Space Concepts Teradata - Secondary Index Teradata - Statistics Teradata - Compression Teradata - Explain Teradata - Hashing Algorithm Teradata - Join Index Ter...
--value case 语句 case AA when v1 then r1 when v2 then r2 else null end --case 变种 NULLIF NULLIF returns NULL if its arguments are equal. Otherwise, it returns its first argument, scalar_expression_1. --case 变种 COALESCE COALESCE returns NULL if all its arguments evaluate to null. O...
Teradata - CASE & COALESCE Teradata - Primary Index Teradata - Joins Teradata - SubQueries Teradata Advanced Teradata - Table Types Teradata - Space Concepts Teradata - Secondary Index Teradata - Statistics Teradata - Compression Teradata - Explain Teradata - Hashing Algorithm Teradata - Join Index Ter...
以下示例创建一个JOIN INDEX通过加入Employee和Salary表名为Employee_Salary_JI. CREATEJOININDEXEmployee_Salary_JIASSELECTa.EmployeeNo,a.FirstName,a.LastName,a.BirthDate,a.JoinedDate,a.DepartmentNo,b.Gross,b.Deduction,b.NetPayFROMEmployeeaINNERJOINSalarybON(a.EmployeeNo = b.EmployeeNo)PRIMARYINDEX(First...
LEFTJOIN ${AUTO_PLGADB}.lga_iata_region t4 ONt3.country_name = t4.country_name )WITHDATA PRIMARYINDEX(airport_iata_cd) ONCOMMITPRESERVEROWS; 27. UNION 与 UNION ALL UNION ---自动去除两个集合合并后重复的记录 UNION ALL ---保留重复记录 ...
o describe the operation of a join plan ouse EXPLAIN to improve performance ouse Collect Statistics to improve performance o use join indexes to improve performance o given a scenario with table definitions, SQL, and data demographics, identify the best performing partitioning definition ...
Union all是多余的,它需要重复扫描数据,进行重复的JOIN 可以用Case when替代union 作业:KPI_NWR_SMS 36、_BILL_QUAN描述:点对点短信计费量脚本: kpi_nwr_sms_bill_quan0600.pl22 6/15/2021用Case When替代UNION (cont.)sel city_id,channel_id,cust_brand_id,sum(stat_values) as stat_valuesfrom ( ...
The Teradata Database will accommodate up to 15 FL/ML/FE applications at one time.Tables defined with Referential integrity, secondary indexes, Join Indexes, Hash Indexes, or Triggers cannot be loaded with FastLoad.Tables with Soft Referential Integrity (V2R5) can be loaded with FastLoad.Du 33...
Teradata RDBMS教程说明书 Teradata
实用教程(Teradata)实用教程（Teradata）陆世潮2008年9月 问题总结 常见问题分类：1.表属性不对:Set/Multiset >问题：INSERT操作慢 2.主索引(PI)设置不合理 > >>> 问题1：数据倾斜度大，空间爆满。问题2：JOIN操作，数据需要重分布。问题：全表扫描问题：系统无法优化执行计划问题：系统无法找到最优化的执行计划 ...