Class: Google::Spanner::V1::PartialResultSet
- Inherits:
-
Object
- Object
- Google::Spanner::V1::PartialResultSet
- Defined in:
- lib/google/cloud/spanner/v1/doc/google/spanner/v1/result_set.rb
Overview
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.
Instance Attribute Summary collapse
-
#chunked_value ⇒ true, false
If true, then the final value in values is chunked, and must be combined with more values from subsequent
PartialResultSet
s to obtain a complete field value. -
#metadata ⇒ Google::Spanner::V1::ResultSetMetadata
Metadata about the result set, such as row type information.
-
#resume_token ⇒ String
Streaming calls might be interrupted for a variety of reasons, such as TCP connection loss.
-
#stats ⇒ Google::Spanner::V1::ResultSetStats
Query plan and execution statistics for the statement that produced this streaming result set.
-
#values ⇒ Array<Google::Protobuf::Value>
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.
Instance Attribute Details
#chunked_value ⇒ true, false
Returns If true, then the final value in
values is chunked, and must be
combined with more values from subsequent PartialResultSet
s to obtain a
complete field value.
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# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/result_set.rb', line 147 class PartialResultSet; end |
#metadata ⇒ Google::Spanner::V1::ResultSetMetadata
Returns Metadata about the result set, such as row type information. Only present in the first response.
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# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/result_set.rb', line 147 class PartialResultSet; end |
#resume_token ⇒ String
Returns 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.
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# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/result_set.rb', line 147 class PartialResultSet; end |
#stats ⇒ Google::Spanner::V1::ResultSetStats
Returns 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.
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# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/result_set.rb', line 147 class PartialResultSet; end |
#values ⇒ Array<Google::Protobuf::Value>
Returns 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 chunkedstring
: concatenate the stringslist
: concatenate the lists. If the last element in a list is astring
,list
, orobject
, 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. "1", "2" => "1", "b": 2"
= Overlapping object fields are merged. "1", "2" => "12"
= Examples of merging objects containing lists of strings. ["1"], ["2"] => ["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 PartialResultSet
s 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 PartialResultSet
s encodes two rows, one
containing the field value "Hello"
, and a second containing the
field value "World" = "W" + "orl" + "d"
.
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# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/result_set.rb', line 147 class PartialResultSet; end |