On Mon, Jul 18, 2016 at 10:05 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Jan Wieck <jan@wi3ck.info> writes: > In the meantime, would it be appropriate to backpatch the double linking > of memory context children at this time? I believe it has had plenty of > testing in the 9.6 cycle to be sure it didn't break anything.
I'm concerned about the ABI breakage risk from changing a data structure as fundamental as MemoryContext. Yeah, code outside utils/mmgr probably *shouldn't* be looking at that struct, but that doesn't mean it isn't. In the past we've generally only taken that sort of risk when there was no other way to fix a bug; and this patch isn't a bug fix. While this does help performance in some corner cases, I don't think it's enough of an across-the-board win to justify the risk of back-patching.
I would consider mucking with the linked lists of memory context children inside
of 3rd party code a really bad idea, but I concede. It isn't a bug fix and there is
that small risk that somebody did precisely that, so no backpatch.
