The Experts below are selected from a list of 6 Experts worldwide ranked by ideXlab platform
Randall Weis - One of the best experts on this subject based on the ideXlab platform.
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Diagrams and Other Notations
Managing Time in Relational Databases, 2010Co-Authors: Tom Johnston, Randall WeisAbstract:This chapter introduces the schema common to all asserted version tables, as well as various diagrams, and notations. All of the concepts such as objects, episodes, versions, and Assertions, and the two principal semantic constraints of temporal entity integrity and temporal referential integrity, are physically realized as rows in tables that are all based on the schema of asserted version tables. All asserted version tables have the same nonbusiness-data columns. All the other columns, such as row number, object identifier, effective Begin Date, effective end Date, and effective end Date are part of the syntax common to all asserted version tables, part of the bitemporal machinery of Asserted Versioning. For Asserted Versioning, it is necessary to have a row creation Date which is distinct from the Assertion Begin Date. The chapter presents diagrams that are used to illustrate Asserted Versioning. The “basic diagram” of an asserted version table contains five main components: current clock tick; a temporal insert, upDate or delete transaction; a calendar timeline covering approximately four years, in monthly increments; a stacked series of Assertion time snapshots of the table; and the table itself, including all rows across all effective and Assertion times. The chapter also explains how Asserted Versioning supports the dynamic views that hide the complexities of asserted version tables schema from query authors who would otherwise are likely be confused by the complexity.
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The Basic Scenario
Managing Time in Relational Databases, 2010Co-Authors: Tom Johnston, Randall WeisAbstract:When an object is represented by a row in a nontemporal table, the sequence of events Begins with the insertion of that row, continues with zero or more upDates, and either continues on with no further activity, or ends when the row is eventually deleted. When an object is represented in an asserted version table, the result includes one row corresponding to the insert in the nontemporal table, additional rows corresponding to the upDates to the original row in the nontemporal table, and an additional row if a delete eventually takes place. This sequence of events constitutes what is called the basic scenario of activity against both conventional and asserted version tables. This chapter describes how the basic scenario works when the target of that activity is an asserted version table. Basic temporal transactions are temporal transactions that do not specify any bitemporal parameters. Any one or more of three bitemporal parameters—an Assertion Begin Date, an effective Begin Date or an effective end Date—may be specified on a temporal transaction. On a basic temporal transaction, none of them are specified. A temporal delete is translated into a set of physical upDate transactions that withdraw the affected versions, followed by either one or two physical insert transactions that delimit the scope of the delete and, if necessary, any number of withdrawals and replacements to adjust episode Begin Dates that may have been affected.
Tom Johnston - One of the best experts on this subject based on the ideXlab platform.
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Diagrams and Other Notations
Managing Time in Relational Databases, 2010Co-Authors: Tom Johnston, Randall WeisAbstract:This chapter introduces the schema common to all asserted version tables, as well as various diagrams, and notations. All of the concepts such as objects, episodes, versions, and Assertions, and the two principal semantic constraints of temporal entity integrity and temporal referential integrity, are physically realized as rows in tables that are all based on the schema of asserted version tables. All asserted version tables have the same nonbusiness-data columns. All the other columns, such as row number, object identifier, effective Begin Date, effective end Date, and effective end Date are part of the syntax common to all asserted version tables, part of the bitemporal machinery of Asserted Versioning. For Asserted Versioning, it is necessary to have a row creation Date which is distinct from the Assertion Begin Date. The chapter presents diagrams that are used to illustrate Asserted Versioning. The “basic diagram” of an asserted version table contains five main components: current clock tick; a temporal insert, upDate or delete transaction; a calendar timeline covering approximately four years, in monthly increments; a stacked series of Assertion time snapshots of the table; and the table itself, including all rows across all effective and Assertion times. The chapter also explains how Asserted Versioning supports the dynamic views that hide the complexities of asserted version tables schema from query authors who would otherwise are likely be confused by the complexity.
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The Basic Scenario
Managing Time in Relational Databases, 2010Co-Authors: Tom Johnston, Randall WeisAbstract:When an object is represented by a row in a nontemporal table, the sequence of events Begins with the insertion of that row, continues with zero or more upDates, and either continues on with no further activity, or ends when the row is eventually deleted. When an object is represented in an asserted version table, the result includes one row corresponding to the insert in the nontemporal table, additional rows corresponding to the upDates to the original row in the nontemporal table, and an additional row if a delete eventually takes place. This sequence of events constitutes what is called the basic scenario of activity against both conventional and asserted version tables. This chapter describes how the basic scenario works when the target of that activity is an asserted version table. Basic temporal transactions are temporal transactions that do not specify any bitemporal parameters. Any one or more of three bitemporal parameters—an Assertion Begin Date, an effective Begin Date or an effective end Date—may be specified on a temporal transaction. On a basic temporal transaction, none of them are specified. A temporal delete is translated into a set of physical upDate transactions that withdraw the affected versions, followed by either one or two physical insert transactions that delimit the scope of the delete and, if necessary, any number of withdrawals and replacements to adjust episode Begin Dates that may have been affected.
