oracle對象定義(英文版)-預覽頁
【正文】 ns, Inc.Tablesn Stored in Tablespacesn Organized in rows and columnsn Contain dataTablespaceTables, indexes, etc.DatafilesSegmentExtentBlocksCopyright 169。 2023 Global Business Solutions, Inc.External File SystemLOB Locatorsn LOB data stored separate from nonLOB data n BFILE data stored separate from databaseTablespace A TableName Add… * (Locators point to LOB and BFILE Locations)Tablespace B Copyright 169。 2023 Global Business Solutions, Inc.Index Typesn Single ColumnIndex RowidOrderNo Block.Seq.File007000 0000A .0004 .0003007000 0000A .0005 .0003OrderNo ItemNo Cust.006989 001 ABC 006989 002 XYZ006989 003 USA007000 001 USA007000 002 GBSI007000 003 TEST007000 004 XYZ007234 005 WESTORDER TABLECopyright 169。 2023 Global Business Solutions, Inc.Function Based Indexn Create on functions or expressionsl User generated PL/SQLl SQL functions (nonaggregate)l External program (C callout)600500300250900660550330275990SALARY * FunctionBasedSingleSQL SELECT salary, salary* FROM employees。 2023 Global Business Solutions, Inc.Advantages of Partitionsn Control data storage across physical devicesn Maintain partition transparencyl Programs do not need to reference partitionsl Programs can take advantage of partitionsCopyright 169。 2023 Global Business Solutions, Inc.Tablespace and Datafile RelationshipTablespaceTables, indexes, etc.DatafilesSegmentExtentn A tablespace is created with one or more datafilesn Datafiles are made up of blocksBlocksCopyright 169。 2023 Global Business Solutions, Inc.Index Segmentsn Created for every indexn Exist as separate physical segments from data segmentn Usually much smaller than associated data segmentBootstrapSegmentRollbackSegmentIndexSegmentIndex SegmentCopyright 169。 2023 Global Business Solutions, Inc.Read Consistencyn When query executes:l Current time determinedl Blocks with same time readl Newer blocks reconstructed with rollback segmentsCustomers Name Address…1 Acme Inc. 123 Ch2 Zachary’s 1234 Br3 Marie’s 4456 Si4 Chimney 9024 FSELECT * FROM customerUPDATE customer . . .Copyright 169。 2023 Global Business Solutions, Inc.Database Blocksn Are:l smallest unit of storagel sized by DB_BLOCK_SIZEl same as buffer in database buffer cachen Correspond to O/S blockn Typically sized as 2k, 4k, 8k, or 16kSegmentExtentBlocksCopyright
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