Function cdbpathlocus_for_insert

src/backend/cdb/cdbpathlocus.c:220–315

* cdbpathlocus_for_insert * Build DistributionKeys that match the policy of the given relation. * * This is used for INSERT or split UPDATE, where 'pathtarget' the target list of * subpath that's producing the rows to be inserted/updated. * * As a side-effect, this assigns sortgrouprefs to any volatile expressions * that are used in the distribution keys. * * If the target table is dist

 * is always partitioned type.
 */
CdbPathLocus
cdbpathlocus_for_insert(PlannerInfo *root, GpPolicy *policy,
						PathTarget *pathtarget)
{
	CdbPathLocus targetLocus;

	Assert(policy->ptype == POLICYTYPE_PARTITIONED);

	/* rows are distributed by hashing on specified columns */
	List	   *distkeys = NIL;
	Index		maxRef = 0;
	bool		failed = false;

	for (int i = 0; i < list_length(pathtarget->exprs); i++)
		maxRef = Max(maxRef, pathtarget->sortgrouprefs[i]);

	for (int i = 0; i < policy->nattrs; ++i)
	{
		AttrNumber	attno = policy->attrs[i];
		DistributionKey *cdistkey;
		Expr	   *expr;
		Oid			typeoid;
		Oid			eqopoid;
		Oid			opfamily = get_opclass_family(policy->opclasses[i]);
		Oid			opcintype = get_opclass_input_type(policy->opclasses[i]);
		List	   *mergeopfamilies;
		EquivalenceClass *eclass;

		expr = list_nth(pathtarget->exprs, attno - 1);
		typeoid = exprType((Node *) expr);

		/*
		 * Look up the equality operator corresponding to the distribution
		 * opclass.
		 */
		eqopoid = get_opfamily_member(opfamily, opcintype, opcintype, 1);

		if (pathtarget->sortgrouprefs[attno - 1] == 0 &&
			contain_volatile_functions((Node *) expr))
		{
			/*
			 * sortgrouprefs should never be zero if the expression is volatile!
			 */
			pathtarget->sortgrouprefs[attno - 1] = ++maxRef;
		}

		/*
		 * Get Oid of the sort operator that would be used for a sort-merge
		 * equijoin on a pair of exprs of the same type.
		 */
		if (failed || eqopoid == InvalidOid || !op_mergejoinable(eqopoid, typeoid))
		{
			/*
			 * It's in principle possible that there is no b-tree operator family
			 * that's compatible with the hash opclass's equality operator. However,
			 * we cannot construct an EquivalenceClass without the b-tree operator
			 * family, and therefore cannot build a DistributionKey to represent it.
			 * Bail out. (That makes the distribution key rather useless.)