Attached is an updated version of the patch series, fixing a couple issues:
1) docs issues, pointed out by Justin Pryzby
2) adds ACL check to statext_extract_expression to verify access to
attributes in the expression(s)
3) adds comment to statext_is_compatible_clause_internal explaining the
ambiguity in extracting expressions for extended stats
4) fixes/improves memory management in compute_expr_stats
5) a bunch of minor comment and code fixes
regards
--
Tomas Vondra
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