Add assertion to verify derived clause has constant RHS

amitlan · amitlan · commit 887160d1beae · 2025-04-04T10:45:05.000+09:00
find_derived_clause_for_ec_member() searches for a previously-derived clause that equates a non-constant EquivalenceMember to a constant. It is only called for EquivalenceClasses with ec_has_const set, and with a non-constant member the EquivalenceMember to search for. The matched clause is expected to have the non-constant member on the left-hand side and the constant EquivalenceMember on the right. Assert that the RHS is indeed a constant, to catch violations of this structure and enforce assumptions made by generate_base_implied_equalities_const(). Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-by: Amit Langote <amitlangote09@gmail.com> Discussion: https://postgr.es/m/CAExHW5scMxyFRqOFE6ODmBiW2rnVBEmeEcA-p4W_CyuEikURdA@mail.gmail.com
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
@@ -2664,7 +2664,10 @@ find_derived_clause_for_ec_member(EquivalenceClass *ec,
 		 * members on the left side of derived clauses.
 		 */
 		if (rinfo->left_em == em)
+		{
+			Assert(rinfo->right_em->em_is_const);
 			return rinfo;
+		}
 	}
 	return NULL;
 }

Original file line number	Diff line number	Diff line change
`@@ -2664,7 +2664,10 @@ find_derived_clause_for_ec_member(EquivalenceClass *ec,`
`2664`	`2664`	`* members on the left side of derived clauses.`
`2665`	`2665`	`*/`
`2666`	`2666`	`if (rinfo->left_em == em)`
	`2667`	`+ {`
	`2668`	`+ Assert(rinfo->right_em->em_is_const);`
`2667`	`2669`	`return rinfo;`
	`2670`	`+ }`
`2668`	`2671`	`}`
`2669`	`2672`	`return NULL;`
`2670`	`2673`	`}`