Struct google_spanner1::PartialResultSet

pub struct PartialResultSet {
    pub chunked_value: Option<bool>,
    pub resume_token: Option<String>,
    pub values: Option<Vec<String>>,
    pub metadata: Option<ResultSetMetadata>,
    pub stats: Option<ResultSetStats>,
}

Partial results from a streaming read or SQL query. Streaming reads and SQL queries better tolerate large result sets, large rows, and large values, but are a little trickier to consume.

Activities

This type is used in activities, which are methods you may call on this type or where this type is involved in. The list links the activity name, along with information about where it is used (one of request and response).

• instances databases sessions streaming read projects (response)
• instances databases sessions execute streaming sql projects (response)

Fields

chunked_value: Option<bool>

If true, then the final value in values is chunked, and must be combined with more values from subsequent PartialResultSets to obtain a complete field value.

resume_token: Option<String>

Streaming calls might be interrupted for a variety of reasons, such as TCP connection loss. If this occurs, the stream of results can be resumed by re-sending the original request and including resume_token. Note that executing any other transaction in the same session invalidates the token.

values: Option<Vec<String>>

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".

metadata: Option<ResultSetMetadata>

Metadata about the result set, such as row type information. Only present in the first response.

stats: Option<ResultSetStats>

Query plan and execution statistics for the statement that produced this streaming result set. These can be requested by setting ExecuteSqlRequest.query_mode and are sent only once with the last response in the stream. This field will also be present in the last response for DML statements.

Trait Implementations

impl ResponseResult for PartialResultSet

impl Clone for PartialResultSet

fn clone(&self) -> PartialResultSet

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for PartialResultSet

fn default() -> PartialResultSet

Returns the "default value" for a type.

impl Debug for PartialResultSet

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Serialize for PartialResultSet

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error> where
    __S: Serializer, 

Serialize this value into the given Serde serializer.

impl<'de> Deserialize<'de> for PartialResultSet

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error> where
    __D: Deserializer<'de>, 

Deserialize this value from the given Serde deserializer.