DataStage官方培训教程7.ppt

《DataStage官方培训教程7.ppt》由会员分享，可在线阅读，更多相关《DataStage官方培训教程7.ppt（17页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、DataStage DataStage EssentialsEssentialsHashed FilesServer EditionThisdocumentandthesoftwaredescribedhereinarethepropertyofAscentialSoftwareCorporationanditslicensorsandcontainconfidentialtradesecrets.Allrightstothispublicationarereserved.Nopartofthisdocumentmaybereproduced,transmitted,transcribed,s

2、toredinaretrievalsystemortranslatedintoanylanguage,inanyformorbyanymeans,withoutpriorpermissionfromAscentialSoftwareCorporation.Copyright2003AscentialSoftwareCorporation.AllrightsReservedAscentialSoftwareCorporationreservestherighttomakechangestothisdocumentandthesoftwaredescribedhereinatanytimeandw

3、ithoutnotice.Nowarranty isexpressedorimpliedotherthananycontainedinthetermsandconditionsofsale.AscentialSoftwareCorporation50WashingtonStreetWestboro,MA01581-1021USAPhone:(508)366-3888Fax:(508)366-3669Ascential,DataStage,INTEGRITY,MetaRecon,MetaStageandMetaBrokeraretrademarksofAscentialSoftwareCorpo

4、ration.PickisaregisteredtrademarkofPickSystems.AscentialSoftwareisnotalicenseeofPickSystems.Othertrademarksandregisteredtrademarksarethepropertyoftherespectivetrademarkholder.12/23/2022Upon module completion,students will be able to:Define what a hashed file isList different types of hashed filesLis

5、t various uses for hashed filesCreate hashed filesSource hashed filesUse caching attributes to accelerate reads and writesImport metadata from hashed filesDelete hashed filesModule Objectives 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights Reserved Reproduction and/or Redistr

6、ibution Is Prohibited.What is a Hashed File?A DataStage file written to the file systemMost use a hashing algorithm based on key column valuesFiles can be cataloged in the projects VOC file for easy retrieval 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights Reserved Reproducti

7、on and/or Redistribution Is Prohibited.Types of Hashed Files21 different typesType 1 and 19 do not use a hashing algorithmTypes 2-18 are static hashed files and use a hashing algorithmType 25 is static and uses a B-tree algorithmType 30 is dynamic and uses a hashing algorithm 2002 Ascential Software

8、 Corp.All rights reserved.Corporation.All Rights Reserved Reproduction and/or Redistribution Is Prohibited.Uses of Hashed FilesGood for locally storing tables of a remote database that will be read from frequentlyGood as an intermediate file location in sequences of jobsMain use is as a reference lo

9、okup table 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights Reserved Reproduction and/or Redistribution Is Prohibited.Hashing Algorithms(Static File Types)CharactertypeLocationwheremostvariationoccursinkeycolumnRightMiddleLeftAnyWhollynumeric261014Numeric&separators371115ASCII

10、481216Any591317 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights Reserved Reproduction and/or Redistribution Is Prohibited.HashingAlgorithmInserting Records into Hashed FilesGroup1Group2Group3Group4Group5 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights

11、Reserved Reproduction and/or Redistribution Is Prohibited.Overflow GroupsGroup1Group2Group3Group4Group5Header204840966144819210240GroupAddressoverflowGroup212288When there is not enough space remaining in a group,the group overflows 2002 Ascential Software Corp.All rights reserved.Corporation.All Ri

12、ghts Reserved Reproduction and/or Redistribution Is Prohibited.Creating Hashed FilesInsert the name of the hashed filecan use parameters Let the job create the hashed fileCan optionally use the CREATE.FILE command from a DataStage command shell or program 2002 Ascential Software Corp.All rights rese

13、rved.Corporation.All Rights Reserved Reproduction and/or Redistribution Is Prohibited.How many groups to create initiallyOptions for Creating Hashed FilesWhat percentage of file capacity to create a new groupWhich type of file to createHow large the groups will beWhat percentage of file capacity to

14、remove a groupSimilar to dropping a table 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights Reserved Reproduction and/or Redistribution Is Prohibited.Hashed File LocationsCreate and/or write records to a hashed file in a specific projectdoesnt have to be yours!Create and/or wri

15、te records to a hashed file in a specific directorycan present issues 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights Reserved Reproduction and/or Redistribution Is Prohibited.Write CachingEnabled from Input page of hashed file stageAllows records to be written to memory buff

16、er initially and flushed to disk onceI/O is extremely expensivethis minimizes writes to diskCan present issues when reading from a hashed file at the same time 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights Reserved Reproduction and/or Redistribution Is Prohibited.Importing

17、Metadata from a Hashed FileChoose the project from the drop-down listAvailable hashed files within the project appearselect one or multiples 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights Reserved Reproduction and/or Redistribution Is Prohibited.Sourcing a Hashed FileInsert

18、the name of the hashed file or use drop-down listcan use parameters Enable or disable read cachingfour methods 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights Reserved Reproduction and/or Redistribution Is Prohibited.Read CachingEnabled from Output page of hashed file stageFo

19、ur methods are availablebe sure to choose the correct methodAllows records to be read into memory buffer I/O is extremely expensivethis minimizes reads from diskCan present issues when writing to a hashed file at the same time 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights R

20、eserved Reproduction and/or Redistribution Is Prohibited.Deleting Hashed FilesNot advisable to manually delete operating system directories and filesIssue DELETE.FILE command from DataStage Administrator or DataStage command shellCreate shell script to run delete_file.exe program and supply hashed file namedelete_file.exe program is installed when the server is installed and is located in the servers engine directory in the bin subdirectory 2002 Ascential Software Corp.All rights reserved.Corporation.All Rights Reserved Reproduction and/or Redistribution Is Prohibited.