On Sun, Feb 02, 2014 at 05:09:06PM -0800, Peter Geoghegan wrote: > However, it also occurs to me that strxfrm() blobs have another useful > property: We (as, say, the author of an equality operator on text, an > operator intended for a btree operator class) *can* trust a strcmp()'s > result on blobs, provided the result isn't 0/equal, *even if the blobs > are truncated*. So maybe a better scheme, and certainly a simpler one > would be to have a pseudo-attribute in inner pages only with, say, the > first 8 bytes of a strxfrm() blob formed from the logically-leading > text attribute of the same indexTuple. Because we're only doing this > on inner pages, there is a very good chance that that will be good > enough most of the time. This also allows us to reduce bloat very > effectively.
(A bit late to the party). This idea has come up before and the most annoying thing is that braindead strxfrm api. Namely, to strxfrm a large strings you need to strxfrm it completely even if you only want the first 8 bytes. That said, since btree index tuples are limited to <3k anyway, the overhead probably isn't that bad. I think it would make a noticable difference if it can be made to work. Have a nice day, -- Martijn van Oosterhout <klep...@svana.org> http://svana.org/kleptog/ > He who writes carelessly confesses thereby at the very outset that he does > not attach much importance to his own thoughts. -- Arthur Schopenhauer
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