SAP HANA 基础架构简介（二）

ndexServer–Connection 和Session 管理

• 为Clients 创建和管理sessions and connections
• 一旦a session 创建clients 用SQL statements 与index server通讯
  • Analytical applications may also use the multidimensional query language MDX (MultiDimensionaleXpressions)
• Connection ID in trace file entries: [11097]{421970}[117779] 2013-05-21 15:03:15.318517 e CalcEngine

 

 

IndexServer–Transaction Manager

• Each SQL statement is processed in the context of a transaction
• New sessions 指定到a new transaction
• Coordinates transactions
• Controls transactional isolation
• 追踪running and closed transactions
• 当一个transaction committed 或rolled back, 通知相关engine(s)
• Transaction ID in trace file entries:

[11097]{421970}[117779] 2013-05-21 15:03:15.318517 e CalcEngine

Index Server –Repository

• 通过Repository REST API通信
  • Request and response consist of a document in JavaScript Object Notation (JSON) and not HTTP
  • Repository REST access is tunneled through the SQL layer via SQL procedure REPOSITORY_REST
• remote access 通过REST 接口打开和关闭transaction
• 维护~ 30 (Column Store) tables in schema _SYS_REPO object 信息, e.g.:
  • ACTIVE_OBJECT
  • INACTIVE_OBJECT
• 用object ID (OID) and version定义一个Object
• Repository object 有命名和种类(e.g. table, procedure, view, web content, JavaScript for XSEngine,…)

 

Index Server –Authorization Manager

• 确保授权用户只能操作它们被授予权限的作业
• For each SQL statement type (e.g. SELECT, UPDATE, EXECUTE) a corresponding privilege exists that the executing user needs to have
  • Additionally, objects in the database (e.g. tables, views, stored procedures) have an owner, that can access the objects and grant privileges on them
• Scenario: The SQL Processor or CalcEngine executes a query where a certain table, view or stored procedure is accessed
  • Then the SQL Processor or CalcEnginewill call the Authorization Manager to check whether the required privilege has been granted to the current user

Index Server –Metadata Manager

• Metadata of all objects 存储在Catalog中
  • Metadata Manager manages the catalog
  • Catalog is stored in Row Store tables
• 在多节点系统中the metadata 共享在所有服务器上
  • The master nodes Index Server acts as a metadata master
  • The metadata managers on the slave nodes retrieve the metadata from the metadata master and store it in a local cache as read-only copies

Index Server –SQL Processor

• SQL Processor 接收incoming SQL requests
• 执行data manipulation statements
• Forwards…
  • data definition statements to the Metadata Manager
  • transaction control statements to the Transaction Manager
  • planning commands to the planning engine
• SQL Processor and Calculation Engine 都包含optimizer
  • To execute these plans, the SQL Processor and Calculation Engine invoke the row store or column store

Index Server –Planning Engine

• 允许数据库层面执行planningoperations
  • e.g. Create a new version of a data set as a copy of an existing one while applying filters and transformations
• Uses case is mainly financial planning
  • Example: Planning data for a new year is created as a copy of the data from the previous year
• Implements planning commands that are used by integrated planning in SAP NetWeaverBusiness Warehouse
  • Typically these planning commands 在 the ABAP application server执行
  • 使用planning engine 可以在HANA database 层面更有效

 

Index Server –Calculation Engine

• Orchestrates OLAP Engine and Join Engine
• 事项商务逻辑
  • e.g. currency conversion
• Users create in the modeler a Calc. Plan to define data sources (e.g. tables, views, other Calc. Scenarios, everything the Column Store supports) as inputs and different operations (Join, aggregation, projection) for data manipulation
  • Stored Procedures are realized as Calc. Models
  • Calc. Models≡ Calc. Scenarios
• To execute SELECT on a Calc. Scenario, a Calc. View is created that points to the Calc. Scenario
  • Modeler does this when a scenario is activated
• Calc. Views 存储在 the Catalog
• Calc. Scenarios 存储在 Repository
  • Stored in JavaScript Object Notation (JSON)
• 重要的 Monitors:
  • SYS.M_CE_CALCSCENARIOS
  • SYS.M_CE_CALCVIEW_DEPENDENCIES
    • Shows what views point to what Calc. Scenarios
    • Multiple entries per Calc. Scenario are possible