摘要:
Techniques are provided for providing mappings between logical time values and real time values in a multinode system. The techniques include, if a first event occurs, then writing an LTV-to-RTV mapping to a non-volatile data structure. If a second event occurs, then a check is performed to determine whether any of the LTV-to-RTV mappings in the volatile data structure are newer than all LTV-to-RTV mappings in a non-volatile data structure. If there are newer mappings in the volatile data structure, then one or more LTV-to-RTV mappings are written to the non-volatile data structure based on those “newer” LTV-to-RTV mappings from the volatile data structure. Upon receiving a request an LTV for a particular RTV, the particular RTV is determined based on information from an information source such as the volatile data structure or the non-volatile data structure.
摘要:
Techniques are provided for guaranteed undo retention. The techniques include a database server attempting to store undo information in undo storage. In order to store the undo information, the database server may overwrite expired undo records; write to empty undo extents; allocate new undo extents and write to the newly-allocated extents; or overwrite unexpired undo records that do not have guaranteed undo retention. If an undo record does not have guaranteed undo retention, then the undo record may be overwritten before the expiration time has elapsed. If no undo extent is empty or unallocated, and if all of the undo records are unexpired and have guaranteed undo retention, then the database system has, at least temporarily, run out of usable and reusable space and an error may be reported to an appropriate party.
摘要:
A method and apparatus for data recovery are disclosed. Undo tablespace size is calculated for user-specified undo retention time based on system statistics collected over a period of time specified by a history time parameter.
摘要:
A method and apparatus for creating a target database on a target platform based on a source database on a source platform is provided. A target database is created on the target platform based on data, metadata (for example, data in the system tablespace and control files), and external objects (for example, password files and externally stored tables) comprised within the source database. Data and metadata stored in tablespaces of the source database are converted to the format compatible with the target platform. The conversion of the data and metadata may be performed either at the source database or the target database. Redo information and undo information of the source database are not copied from the source database to the target database. Certain files, e.g., a password files, and links to externally stored object may be recreated on the target database.
摘要:
Techniques are provided for guaranteed undo retention. The techniques include a database server attempting to store undo information in undo storage. In order to store the undo information, the database server may overwrite expired undo records; write to empty undo extents; allocate new undo extents and write to the newly-allocated extents; or overwrite unexpired undo records that do not have guaranteed undo retention. If an undo record does not have guaranteed undo retention, then the undo record may be overwritten before the expiration time has elapsed. If no undo extent is empty or unallocated, and if all of the undo records are unexpired and have guaranteed undo retention, then the database system has, at least temporarily, run out of usable and reusable space and an error may be reported to an appropriate party.
摘要:
Techniques are provided for providing mappings between logical time values and real time values for a database. The techniques include, if a first event related to the database occurs, writing an entry of a current LTV and a current RTV in a volatile mapping data structure; and if a second event related to the database occurs, writing one or more entries in a non-volatile mapping data structure based on information contained in the volatile mapping data structure. The techniques also include, once a request from a requestor to provide an LTV that is mapped to a particular RTV is received, determining the LTV for the particular RTV, based on the particular RTV and information from a source, wherein the source is one of the volatile mapping data structure and the non-volatile mapping data structure; and providing the LTV that is mapped to the particular RTV to the requestor.
摘要:
Techniques are provided for providing mappings between logical time values and real time values in a multinode system. The techniques include, if a first event occurs, then writing an LTV-to-RTV mapping to a non-volatile data structure. If a second event occurs, then a check is performed to determine whether any of the LTV-to-RTV mappings in the volatile data structure are newer than all LTV-to-RTV mappings in a non-volatile data structure. If there are newer mappings in the volatile data structure, then one or more LTV-to-RTV mappings are written to the non-volatile data structure based on those “newer” LTV-to-RTV mappings from the volatile data structure. Upon receiving a request an LTV for a particular RTV, the particular RTV is determined based on information from an information source such as the volatile data structure or the non-volatile data structure.
摘要:
Techniques are provided for providing mappings between logical time values and real time values for a database. The techniques include, if a first event related to the database occurs, writing an entry of a current LTV and a current RTV in a volatile mapping data structure; and if a second event related to the database occurs, writing one or more entries in a non-volatile mapping data structure based on information contained in the volatile mapping data structure. The techniques also include, once a request from a requestor to provide an LTV that is mapped to a particular RTV is received, determining the LTV for the particular RTV, based on the particular RTV and information from a source, wherein the source is one of the volatile mapping data structure and the non-volatile mapping data structure; and providing the LTV that is mapped to the particular RTV to the requestor.
摘要:
A method and apparatus for creating a target database on a target platform based on a source database on a source platform is provided. A target database is created on the target platform based on data, metadata (for example, data in the system tablespace and control files), and external objects (for example, password files and externally stored tables) comprised within the source database. Data and metadata stored in tablespaces of the source database are converted to the format compatible with the target platform. The conversion of the data and metadata may be performed either at the source database or the target database. Redo information and undo information of the source database are not copied from the source database to the target database. Certain files, e.g., a password files, and links to externally stored object may be recreated on the target database.
摘要:
A method and apparatus for data recovery are disclosed. Undo tablespace size is calculated for user-specified undo retention time based on system statistics collected over a period of time specified by a history time parameter.