On Fri, Jul 13, 2018 at 10:10 AM, Heikki Linnakangas <hlinn...@iki.fi> wrote: > I'm still a bit scared about using pd_prune_xid to store the XID that > prevents recycling the page too early. Can we use some field in > GISTPageOpaqueData for that, similar to how the B-tree stores it in > BTPageOpaqueData?
What's your reason for being scared? It seems to me that the alternatives being proposed (altering the size of the special space, or sometimes repurposing a field for some other purpose) have their own associated scariness. If I had my druthers, I'd nuke pd_prune_xid from orbit -- it's a piece of seemingly heap-specific data that is kept in the generic page header rather than in the heap's special space. Other AMs like btree or zheap may have different needs; one size does not fit all. That said, since getting rid of pd_prune_xid seems impractical, maybe it makes more sense to reuse it than to insist on leaving it idle and consuming space elsewhere in the page. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
