Method querySinglePartiQL

backend/plugin/db/dynamodb/dynamodb.go:208–290

(ctx context.Context, statement string, queryContext db.QueryContext)

}

func (d *Driver) querySinglePartiQL(ctx context.Context, statement string, queryContext db.QueryContext) (*v1pb.QueryResult, error) {
	result := &v1pb.QueryResult{}
	input := &dynamodb.ExecuteStatementInput{
		Statement: &statement,
	}
	if queryContext.Limit > 0 {
		input.Limit = new(int32(queryContext.Limit))
	}

	var nextToken *string
	rowMap := make(map[string][]*v1pb.RowValue)
	// TODO(zp): Our proto is not designed for NoSQL, whose data is not fixed. So we only use the last row to determine the column type.
	columnTypeMap := make(map[string]string)
	totalRowCount := 0
	for {
		input.NextToken = nextToken
		output, err := d.client.ExecuteStatement(ctx, input)
		if err != nil {
			return nil, err
		}
		for _, item := range output.Items {
			totalRowCount++
			meta := convertAttributeValueMapToRow(item)
			allKeySet := make(map[string]bool)
			for key := range rowMap {
				allKeySet[key] = true
			}
			curKeySet := make(map[string]*dynamodbQueryResultMeta, len(meta))
			for key, value := range meta {
				curKeySet[key] = value
				allKeySet[key] = true
			}
			for key := range allKeySet {
				_, inRowMap := rowMap[key]
				_, inCurKeySet := curKeySet[key]
				// 1. The key appears in the rowMap, and appears in the current row, we append the value to the row.
				if inRowMap && inCurKeySet {
					rowMap[key] = append(rowMap[key], curKeySet[key].value)
					columnTypeMap[key] = curKeySet[key].columnType
				}
				// 2.If the key appears in the row map, but does not appear in the current row, we append nil to the row.
				if inRowMap && !inCurKeySet {
					rowMap[key] = append(rowMap[key], nil)
				}
				// 3. If the key appears in the current row, but does not appear in the row map, it means that the current row has a new column, we should
				// backfill the previous rows with nil.
				if !inRowMap && inCurKeySet {
					for i := 0; i < totalRowCount-1; i++ {
						rowMap[key] = append(rowMap[key], nil)
					}
					rowMap[key] = append(rowMap[key], curKeySet[key].value)
					columnTypeMap[key] = curKeySet[key].columnType
				}
			}
		}
		nextToken = output.NextToken
		if nextToken == nil {
			break