On Wed, Sep 14, 2022 at 11:33 PM Peter Geoghegan <p...@bowt.ie> wrote: > > On Wed, Sep 14, 2022 at 3:18 AM John Naylor
> > Furthermore, it doesn't have to anticipate the maximum size, so there > > is no up front calculation assuming max-tuples-per-page, so it > > automatically uses less memory for less demanding tables. > > The final number of TIDs doesn't seem like the most interesting > information that VM snapshots could provide us when it comes to > building the dead_items TID data structure -- the *distribution* of > TIDs across heap pages seems much more interesting. The "shape" can be > known ahead of time, at least to some degree. It can help with > compression, which will reduce cache misses. My point here was simply that spilling to disk is an admission of failure to utilize memory efficiently and thus shouldn't be a selling point of VM snapshots. Other selling points could still be valid. -- John Naylor EDB: http://www.enterprisedb.com
