values property

List<Object> values
read / write

A streamed result set consists of a stream of values, which might be split into many PartialResultSet messages to accommodate large rows and/or large values. Every N complete values defines a row, where N is equal to the number of entries in metadata.row_type.fields.

Most values are encoded based on type as described here.

It is possible that the last value in values is "chunked", meaning that the rest of the value is sent in subsequent PartialResultSet(s). This is denoted by the chunked_value field. Two or more chunked values can be merged to form a complete value as follows:

  • bool/number/null: cannot be chunked
  • string: concatenate the strings
  • list: concatenate the lists. If the last element in a list is a string, list, or object, merge it with the first element in the next list by applying these rules recursively.
  • object: concatenate the (field name, field value) pairs. If a field name is duplicated, then apply these rules recursively to merge the field values.

Some examples of merging:

# Strings are concatenated.
"foo", "bar" => "foobar"

# Lists of non-strings are concatenated.
[2, 3], [4] => [2, 3, 4]

# Lists are concatenated, but the last and first elements are merged
# because they are strings.
["a", "b"], ["c", "d"] => ["a", "bc", "d"]

# Lists are concatenated, but the last and first elements are merged
# because they are lists. Recursively, the last and first elements
# of the inner lists are merged because they are strings.
["a", ["b", "c"]], [["d"], "e"] => ["a", ["b", "cd"], "e"]

# Non-overlapping object fields are combined.
{"a": "1"}, {"b": "2"} => {"a": "1", "b": 2"}

# Overlapping object fields are merged.
{"a": "1"}, {"a": "2"} => {"a": "12"}

# Examples of merging objects containing lists of strings.
{"a": ["1"]}, {"a": ["2"]} => {"a": ["12"]}

For a more complete example, suppose a streaming SQL query is yielding a result set whose rows contain a single string field. The following PartialResultSets might be yielded:

{
  "metadata": { ... }
  "values": ["Hello", "W"]
  "chunked_value": true
  "resume_token": "Af65..."
}
{
  "values": ["orl"]
  "chunked_value": true
  "resume_token": "Bqp2..."
}
{
  "values": ["d"]
  "resume_token": "Zx1B..."
}

This sequence of PartialResultSets encodes two rows, one containing the field value "Hello", and a second containing the field value "World" = "W" + "orl" + "d".

The values for Object must be JSON objects. It can consist of num, String, bool and null as well as Map and List values.

Implementation

core.List<core.Object> values