Copying compressed pages without uncompressing the compressed pages

Methods, devices and systems to make compressed backup copies of in-use compressed database indices are described. In general, an "oldest" time at which index pages in working memory had been updated is identified. Compressed index pages may be directly copied without the need to bring the...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser: Cline, Richard W, Price, Thomas G
Format: Patent
Sprache:eng
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Beschreibung
Zusammenfassung:Methods, devices and systems to make compressed backup copies of in-use compressed database indices are described. In general, an "oldest" time at which index pages in working memory had been updated is identified. Compressed index pages may be directly copied without the need to bring them into working memory or uncompressing them. The identified "oldest" time is then associated with the compressed backup copy. In some embodiments, an entire compressed backup copy may be associated with a single point in time (e.g., the identified "oldest" time). In other embodiments, a compressed backup copy may be associated with multiple points in time (e.g., one time for each portion of the compressed index that is being backed-up). Compressed indices copied in accordance with the invention may be used during restore operations to reconstruct database indices using the identified "oldest" time and database log files.