Haas: The State of VACUUM

Robert Haas continues his series on the PostgreSQL VACUUM operation with thissurvey of recent work and unsolved problems. "What is left to bedone? The PostgreSQL development community has made great progress inreducing the degree to which VACUUM performs unnecessary scans of tablepages, but basically no progress at all in avoiding unnecessary scanning ofindex pages. For instance, even a VACUUM which finds no dead row versionswill still scan btree indexes to recycle empty pages."