On 2025-09-06 20:31:53 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> After contemplating things for awhile, I think that feichanghong’s
> idea is the right one after all: in each of the functions that switch
> into hashtable->tempcxt, let's do a reset on the way out, as attached.
> That's straightforward and visibly related to the required data
> lifespan.
I have considered this approach as well, but my concern is that "tempcxt"
is not always an independent memory context. In some cases, it references
another context — for example, in nodeSetOp.c’s "build_hash_table", “tempcxt"
points to "setopstate->ps.ps_ExprContext->ecxt_per_tuple_memory". There is
similar usage in nodeAgg.c as well. I’m not entirely sure that this approach would
not discard data we still need, because the lifespan of
"ps_ExprContext->ecxt_per_tuple_memory" seems to be longer than “tempcxt”.
Should we make tempcxt a completely independent memory context?
—
Thanks
Haiyang Li