oracle對象定義(英文版)(參考版)
2025-02-07 07:35本頁面
【正文】 2023 Global Business Solutions, Inc.演講完畢，謝謝觀看！。 2023 Global Business Solutions, Inc.Define Database Objects Summaryn Tablespaces are logical collections of database objects with one or more datafilesn Upon creation, space is preallocated for tablespacesTablespaceTables, indexes, etc. DatafilesSegmentExtentBlocksCopyright 169。 2023 Global Business Solutions, Inc.Database Extentsn Consist of a set of contiguous blocksn Serve as space allocation for segmentn Deallocated when segment is removedn First extent created as Initial Extentn Grow by Next ExtentSegmentExtentExtentExtentCopyright 169。 2023 Global Business Solutions, Inc.Temporary Segmentsn Provide temporary workspacen Created automatically for joins, indexes, sortsn Created on disk when memory fulln Sized by DEFAULT STORAGE clause of tablespacen Reclaimed by SMONBootstrapSegmentRollbackSegmentIndexSegment Temporary SegmentCopyright 169。 2023 Global Business Solutions, Inc.Rollback Segment Usagen Undo data is written to segmentn Each extent supports multiple transactionsn Each transaction writes to its own block(s)n If extent fills, automatically extendsn If all extents fill, segment wrapsn If segment wraps, undo data overwrittenn If undo data not available, error occurs“Snapshot too old”“Cannot allocate extent”Copyright 169。 2023 Global Business Solutions, Inc.Rollback Segmentsn Record before image of modified datan Allow changes to be undone before mitn Support read consistencyn Support data concurrencyn Support database recoveryn A SYSTEM rollback segment is requiredBootstrapSegmentRollbackSegmentIndexSegmentRollback SegmentCopyright 169。 2023 Global Business Solutions, Inc.Data Segmentsn Stores rows for Tablesn Table featuresl Contains user datal Contains Data Dictionary datan Row Featuresl Contain unlimited number of rowsl Span blocks (chaining)l Columns stored side by sideBootstrapSegmentRollbackSegmentIndexSegmentData SegmentCopyright 169。 2023 Global Business Solutions, Inc.Storage Object and Segment Relationship n Create a storage object in tablespacen Tables, indexes, etc. are preallocated to segmentsSegmentExtentSegmentMySegmentBlocksCopyright 169。 2023 Global Business Solutions, Inc.Index Organized Tablesn Data stored with B*Tree indexn Table must have primary key, which acts as indexn Appropriate for plex or unstructured datal Spatiall OLAPDataDataData90009999DataDataDataDataDataData3001400149990000020234000DataDataData5000700090005000
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