Tomas Vondra <tomas.von...@enterprisedb.com> writes:
> On 3/3/24 07:10, Andy Fan wrote: >> >> Hi, >> >> Here is a updated version, the main changes are: >> >> 1. an shared_detoast_datum.org file which shows the latest desgin and >> pending items during discussion. >> 2. I removed the slot->pre_detoast_attrs totally. >> 3. handle some pg_detoast_datum_slice use case. >> 4. Some implementation improvement. >> > > I only very briefly skimmed the patch, and I guess most of my earlier > comments still apply. Yes, the overall design is not changed. > But I'm a bit surprised the patch needs to pass a > MemoryContext to so many places as a function argument - that seems to > go against how we work with memory contexts. Doubly so because it seems > to only ever pass CurrentMemoryContext anyway. So what's that about? I think you are talking about the argument like this: /* ---------- - * detoast_attr - + * detoast_attr_ext - * * Public entry point to get back a toasted value from compression * or external storage. The result is always non-extended varlena form. * + * ctx: The memory context which the final value belongs to. + * * Note some callers assume that if the input is an EXTERNAL or COMPRESSED * datum, the result will be a pfree'able chunk. * ---------- */ +extern struct varlena * +detoast_attr_ext(struct varlena *attr, MemoryContext ctx) This is mainly because 'detoast_attr' will apply more memory than the "final detoast datum" , for example the code to scan toast relation needs some memory as well, and what I want is just keeping the memory for the final detoast datum so that other memory can be released sooner, so I added the function argument for that. -- Best Regards Andy Fan
