SAP HANA 1.0 SQL Script 开发指南

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"SAP HANA数据库SQL脚本指南" SAP HANA是SAP公司推出的一款高性能的数据分析平台，特别适合实时数据处理和大数据分析。SQL Script在SAP HANA中扮演着关键角色，它允许开发者和管理员利用SQL语言来执行复杂的数据库操作。SAP HANA 1.0 SQL Script指南是针对SAP HANA 1.0版本的一份详细文档，适用于咨询顾问、管理员以及开发者等不同群体。该指南主要涵盖以下几个方面： 1. **SQL Script基础**：介绍SQL Script的基本语法和结构，包括如何创建、修改和删除数据库对象如表、视图、索引等。同时，它会讲解如何使用DML语句（INSERT, UPDATE, DELETE）以及事务控制语句来管理数据。 2. **高级特性**：SQL Script在HANA中支持高级特性，如窗口函数、联接操作、子查询、集合操作等，这些功能使得在HANA上进行复杂的数据分析和计算变得可能。 3. **性能优化**：针对HANA的内存优化特性，指南会介绍如何编写高效的SQL脚本来最大化利用硬件资源，包括使用列式存储、预计算、物化视图等技术。 4. **开发和调试**：解释如何在HANA Studio中使用SQL Script进行开发，包括编写、测试和调试脚本的过程，以及如何利用日志和性能监控工具来诊断和优化脚本性能。 5. **安全性**：指导如何设置用户权限和访问控制，确保数据的安全性和合规性。 6. **实例和最佳实践**：提供实际案例和最佳实践，帮助读者理解如何在真实场景中应用SQL Script，解决具体问题。 7. **版本更新**：由于文档版本为4.0，发布日期为2012年，需要注意的是，随着SAP HANA的后续版本更新，可能引入了新的特性和功能，因此在实际使用时，需要查阅最新文档以获取最准确的信息。 8. **第三方软件集成**：SAP HANA往往与其他软件产品集成，如Microsoft的Windows、Outlook和PowerPoint，IBM的DB2等。文档可能涉及这些集成的兼容性和互操作性问题。请注意，文档中的信息可能随时间发生变化，使用者需留意SAP官方发布的更新和公告，以保持信息的时效性。此外，尊重版权，未经许可不得复制或传播此出版物的内容。

SAP HANA Database – SQLScript Guide

Page 10 of 56 SAP HANA Appliance Software

SQLScript Processing Overview

In order to better understand the features of SQLScript, and their impact on the execution time of a

procedure, it is instructive to understand how SQLScript procedures are processed in the SAP HANA

database, see the picture below.

When a user defines a new procedure, e.g. using the CREATE PROCEDURE statement discussed later

in this document, the SAP HANA database query compiler processes the statement in a similar way to

an SQL statement. In the figure above, the compilation steps are represented by the arrows, and the

data structures used in this process are shown as nodes in the process flow. A step by step analysis of

the process flow follows below:

 Parse the statement - Detect and report simple syntactic errors.

 Check the statements semantic correctness - Derive types for variables and check their use is

consistent.

 Optimize the code - Optimization distinguishes between declarative logic shown in the upper

branch and imperative logic shown in the lower branch. We discuss how the SAP HANA

database recognizes them below.

 Code generation - For declarative logic the compiler creates calculation models to represent

the data flow defined by the SQLScript code. It will be optimized further by the calculation

engine, when it is instantiated. For imperative logic the code blocks are translated into L

nodes

 The calculation models generated in the previous step are combined into a stacked

calculation model.

„L“ is a new language developed by SAP for executing safe procedural code in SAP HANA

Database.

SAP HANA Database – SQLScript Guide

SAP HANA Appliance Software Page 11 of 56

 The compiled procedure creates content in the database catalog and the repository.

Invocation of a procedure can be divided into two phases:

1) Compilation - During compilation the call to the procedure is rewritten for processing by the

calculation engine.

2) Execution - The execution commences with binding actual parameters to the calculation

models generated n the definition phase. When the calculation models are instantiated they

can be optimized based on concrete input provided. Optimizations include predicate or

projection embedding in the database. Finally the instantiated calculation model is executed

using any of the available parts of the SAP HANA database.

With SQLScript one can implement applications both using imperative orchestration logic and

(functional) declarative logic, and this is also reflected in the way SQLScript processing works for both

coding styles. Imperative logic is executed sequentially and declarative logic is executed by exploiting

the internal architecture of the SAP HANA database utilizing its potential for parallelism.

Orchestration-Logic

Orchestration logic is used to implement data flow and control flow logic using DDL-, DML- and SQL-

Query statements as well as imperative language constructs like loops and conditionals. The

orchestration logic can also execute declarative logic that is defined in the functional extension by

calling the corresponding procedures. In order to achieve an efficient execution on both levels, the

statements are transformed into a dataflow graph to the maximum extent possible, i.e. the

compilation step extracts data-flow oriented snippets out of the orchestration logic and maps them

to data-flow constructs. The calculation engine serves as execution engine of the resulting data flow

graph. Since the language L is used as intermediate language for translating SQLScript into a

calculation model, the range of mappings may span the full spectrum – from a single internal L-node

for a complete SQLScript script in its simplest form, up to a fully resolved data-flow graph without

any imperative code left for an internal L-node. Typically the dataflow graph provides more

opportunities for optimization and thus better performance.

To transform the application logic into a complex data flow graph two prerequisites have to be

fulfilled:

 All data flow operations have to be side-effect free, i.e. they must not change any global

state either in the database or in the application logic.

 All control flows can be transformed into a static dataflow graph.

In SQLScript the optimizer will transform a sequence of assignments of SQL query result sets to table

variables into parallelizable dataflow constructs. The imperative logic is usually represented as a

single node in the dataflow graph, and thus it will be executed sequentially.

Example for Orchestration-Logic:

CREATE PROCEDURE orchestrationProc LANGUAGE SQLSCRIPT AS

v_id BIGINT;

v_name VARCHAR(30);

v_pmnt BIGINT;

v_msg VARCHAR(200);

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