Oracle International Corporation

Tuomas Pystynen

Gregory Pongracz

A method and apparatus copies only the data that was in a computer file when the copying process began, allowing other processes to alter the file while it is being copied without introducing inconsistent data into the copy. The file is arranged into sections, with each section containing one or more blocks of data, with each block stored in the file with a serial number higher than the block stored before. The number of blocks in each section is read and stored, and the highest serial number is read and stored. As blocks are copied from a section of the source file into a destination file, the number of blocks in the section are counted, and the count is compared with the number of blocks that were in the section before the blocks were copied. Blocks that would cause the number of blocks in the section to exceed the number of blocks in the section before any blocks were copied are not copied to the destination file, avoiding new blocks added to the end of a section after the copying began. If any of the remaining blocks that would otherwise be copied into the destination file have a serial number greater than the highest serial number read before the blocks were copied, the destination file is discarded and the copying is repeated to avoid incorporating inconsistent data into the copy.

Method and apparatus for accessing a file that can be concurrently written

A method and system periodically copies information from a computer file to a database to preserve non-current information from the file. As information from the file is overwritten by new information, the old information is preserved in the database, allowing non-current information to be used without reprogramming the computer programs or portions of the computer program that read or write the file. If the file is arranged into one or more sections, and new information stored in a section of the file is assigned an identifier higher than the other information in the section, the amount of time required to locate new information in the file can be reduced. Comparing the highest identifier in the section with the highest identifier in the database for that section can identify sections of the file that have received no new information since the last update made to the database.

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Helsinki, Finland

Tuomas Pystynen