Re: BUG #19458: OOM killer in jsonb_path_exists_opr (@?) with malformed JSONPath containing non-existent variables

The growing allocation is leaked temporary JsonValueLists in executePredicate() (local lseq/rseq, ~1482–1547) and the arithmetic helpers executeBinaryArithmExpr() / executeUnaryArithmExpr() (~1561–1684). Each nested comparison or arithmetic subexpression materializes operands via executeItemOptUnwrapResult[NoThrow]() → executeNextItem() → JsonValueListAppend() (~1165, ~2451), but the interim lists are never freed before return. For @? specifically, executeJsonPath() also leaks a local vals list in strict exists mode (~579–586).

Missing vars make the AFL case worse by returning null instead of error, so evaluation continues deep into nested $?()/comparisons instead of stopping at the first $"…" reference. The same leak mechanism is reachable without missing vars — Tom Lane demonstrated this on master (5a2043bf713) with $[*] ? (@ < $) on a large array.

Our missing-variable patch fixes the reported OOM and the @? semantics bug by aborting early. Whether REL_14/15/16 also need a broader fix for interim JsonValueList cleanup is beyond what I can confidently propose; I've tried to pin down where the growth happens for that discussion.

пт, 5 июн. 2026 г. в 13:58, Amit Langote <amitlangote09@gmail.com>:

Hi,

Before I dig into the patch properly after the weekend, one question
on the report itself: has anyone traced why the old path runs away on
memory? We've characterized it as missing-var, then null, then
evaluation continues, then OOM, but I don't think the actual growing
allocation has been pinned down. Mostly want to understand whether the
same runaway is reachable without a missing variable, since raising
the error early wouldn't catch those cases.

- Thanks, Amit