【正文】 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.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.ReadWrite and ReadOnly Tablespacesn ReadWritel Create, alter, and drop database objectsl Defaultn ReadOnlyl Cannot create or alter database objectsl Can drop certain objectsl Can reside on Worm device or CDROM l Eliminate redundant data backupsl Ideal for Data Warehouse applications and Lookup tablesReadWriteReadOnlyCopyright 169。 2023 Global Business Solutions, Inc.Tips for ReadOnly Tablespacesn Organize by modification requirementsl Frequency of data changel Backup requirementl Security requirementl User requirementn Associated datafile cannot be:l Resized or have auto extend set to onl Renamed to a new datafile name or directoryl OfflineCopyright 169。Copyright 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.Bitmap Indexn Bitmap created for each column valuen Common Usagel Very Large Tablesl LowCardinality Columnsn Featuresl Requires minimal storagel Improves performance‘F’BILLLISAANNTED1 00 10 11 0‘M’GENDERCopyright 169。 2023 Global Business Solutions, Inc.Online and Offline Tablespacesn Onlinel Available to applicationsl Typicall