Hi Karl, I'm going down this road myself. In addition to the files Tom Lane pointed out there is also some helpful documentation here:
https://www.postgresql.org/docs/current/storage-toast.html#STORAGE-TOAST-INMEMORY On Wed, Jan 16, 2019 at 2:09 PM Sam Patterson <katorias...@gmail.com> wrote: > Hi all, > > I've recently started developing an extension for Postgres for which I'll > need to create a new variable-length base type. The type will require a > tree-like structure in order to parse sufficiently, which of course > probably means having some sort of recursive data structure, like a struct > that has members which are pointers to itself for child nodes. After doing > some research, specifically looking at how other variable-length data types > store their data, it seems almost all of them store the data in a binary > representation, using bit masks and offsets etc in order to store/access > the data whilst having an in-memory representation that's used to > manipulate the data. > > I presume the purpose for using this approach is because all the data in a > varlena type has to be contiguous, and the moment you start using pointers > this is no longer possible. So my question is, given a structure that looks > something like this, > > typedef struct Node > { > char *data; > Node *left; > Node *right; > } Node; > > am I right in saying that I wouldn't be able to store that representation > on-disk, but instead I'd have to transform it into some binary > representation and back again when writing/reading respectively, are there > any alternatives? > > Regards, > > Karl >
