Unobtrusive copies of actively used compressed indices

At least one storage device tangibly embodying program instructions that, when executed by at least one processor, are configured to cause a general purpose computer to at least:

• identify a target index, at least a first portion of the target index being uncompressed and in working memory and a second portion of the target index being stored in compressed form in a file;
• identify a prior compressed backup of the target index;
• determine an externalization point for the prior compressed backup;
• copy a header of a page from the target index into working memory;
• determine an externalization time of the page based on information in the header of the page;
• and
• if the externalization time of the page is greater than the externalization point of the prior backup externalization point, write the page and an identifier to an output data set, the identifier identifying both the first portion of the target index that was uncompressed and in working memory and the second portion of the target index that was stored in compressed form in the file.

At least one storage device tangibly embodying program instructions that, when executed by at least one processor, are configured to cause a general purpose computer to at least:

• read a first page of a compressed backup copy of a database index;
• decompress the first page while leaving a second page of the compressed backup copy compressed;
• identify, based on a log, a first time previously associated with the first page of the compressed backup copy;
• update the compressed first page by applying updates stored in the log beginning at the first time to a specified second time;
• compress the updated first page;
• store the compressed updated first page and the second page of the compressed backup copy in a storage device;
• and
• record an identifier that identifies both the first page and the second page.