genDeleteRows is mostly running on non-existing keys

[dkropachev]

gemini/pkg/jobs/gen_mutate_stmt.go

Lines 31 to 61 in c93899e

	func GenMutateStmt(s *testschema.Schema, t *testschema.Table, g generators.GeneratorInterface, r *rand.Rand, p *typedef.PartitionRangeConfig, deletes bool) (*typedef.Stmt, error) {
	t.RLock()
	defer t.RUnlock()
	valuesWithToken := g.Get()
	if valuesWithToken == nil {
	return nil, nil
	}
	useLWT := false
	if p.UseLWT && r.Uint32()%10 == 0 {
	useLWT = true
	}
	if !deletes {
	return genInsertOrUpdateStmt(s, t, valuesWithToken, r, p, useLWT)
	}
	switch n := rand.Intn(1000); n {
	case 10, 100:
	return genDeleteRows(s, t, valuesWithToken, r, p)
	default:
	switch rand.Intn(2) {
	case 0:
	if t.KnownIssues[typedef.KnownIssuesJSONWithTuples] {
	return genInsertOrUpdateStmt(s, t, valuesWithToken, r, p, useLWT)
	}
	return genInsertJSONStmt(s, t, valuesWithToken, r, p)
	default:
	return genInsertOrUpdateStmt(s, t, valuesWithToken, r, p, useLWT)
	}
	}
	}

Row deletion should be running on both existing and non-existing records with different ration.
We need to split them into different statements type.