Method GetPlanHints

src/backend/gpopt/utils/COptTasks.cpp:646–872

--------------------------------------------------------------------------- @function: COptTasks::GetPlanHints @doc: Generate an instance of plan hints by parsing the query tree. ---------------------------------------------------------------------------

//
//---------------------------------------------------------------------------
CPlanHint *
COptTasks::GetPlanHints(CMemoryPool *mp, Query *query)
{
	HintState *hintstate = nullptr;
	if (plan_hint_hook != nullptr)
	{
		// Calling plan_hint_hook creates pg_hint_plan hint structures
		// (see optimizer/hints.h).
		hintstate = (HintState *) plan_hint_hook(query);
		if (hintstate != nullptr && hintstate->log_level > 0)
		{
			GPOS_SET_TRACE(EopttracePrintPgHintPlanLog);
		}
	}

	if (nullptr == hintstate)
	{
		return nullptr;
	}

	// Following code translates pg_hint_plan hint structures into ORCA hint
	// structures (see gpopt/hints/CPlanHint.h).

	CPlanHint *plan_hints = GPOS_NEW(mp) CPlanHint(mp);

	// Translate ScanMethodHint => CScanHint
	for (int ul = 0; ul < hintstate->num_hints[HINT_TYPE_SCAN_METHOD]; ul++)
	{
		ScanMethodHint *scan_hint =
			(ScanMethodHint *) hintstate->scan_hints[ul];
		if (nullptr == scan_hint->relname)
		{
			continue;
		}

		CScanHint::EType type = CScanHint::Sentinal;
		switch (scan_hint->base.hint_keyword)
		{
			case HINT_KEYWORD_SEQSCAN:
			{
				type = CScanHint::SeqScan;
				break;
			}
			case HINT_KEYWORD_NOSEQSCAN:
			{
				type = CScanHint::NoSeqScan;
				break;
			}
			case HINT_KEYWORD_INDEXSCAN:
			{
				type = CScanHint::IndexScan;
				break;
			}
			case HINT_KEYWORD_NOINDEXSCAN:
			{
				type = CScanHint::NoIndexScan;
				break;
			}