kudu::client::KuduScanToken Class Reference

A scan descriptor limited to a single physical contiguous location. More...

#include <client.h>

Public Member Functions
Status	IntoKuduScanner (KuduScanner **scanner) const WARN_UNUSED_RESULT
const KuduTablet &	tablet () const
Status	Serialize (std::string *buf) const WARN_UNUSED_RESULT

Static Public Member Functions
static Status	DeserializeIntoScanner (KuduClient *client, const std::string &serialized_token, KuduScanner **scanner) WARN_UNUSED_RESULT

Detailed Description

A scan descriptor limited to a single physical contiguous location.

A KuduScanToken describes a partial scan of a Kudu table limited to a single contiguous physical location. Using the KuduScanTokenBuilder, clients can describe the desired scan, including predicates, bounds, timestamps, and caching, and receive back a collection of scan tokens.

Each scan token may be separately turned into a scanner using KuduScanToken::IntoKuduScanner, with each scanner responsible for a disjoint section of the table.

Scan tokens may be serialized using the KuduScanToken::Serialize method and deserialized back into a scanner using the KuduScanToken::DeserializeIntoScanner method. This allows use cases such as generating scan tokens in the planner component of a query engine, then sending the tokens to execution nodes based on locality, and then instantiating the scanners on those nodes.

Scan token locality information can be inspected using the KuduScanToken::tablet() function.

Member Function Documentation

DeserializeIntoScanner()

static Status kudu::client::KuduScanToken::DeserializeIntoScanner ( KuduClient *  client, const std::string &  serialized_token, KuduScanner **  scanner  )

static

Create a new scanner and set the scanner options.

Parameters

[in]	client	Client to bound to the scanner.
[in]	serialized_token	Token containing serialized scanner parameters.
[out]	scanner	The result scanner. The caller owns the new scanner. The scanner must be opened before use. The scanner will not be set if the returned status is an error.

Returns

Operation result status.

IntoKuduScanner()

Status kudu::client::KuduScanToken::IntoKuduScanner

(

KuduScanner **

scanner

)

const

Create a new scanner.

This method creates a new scanner, setting the result scanner's options according to the scan token.

Parameters

[out]

scanner

The result scanner. The caller owns the new scanner. The scanner must be opened before use. The output parameter will not be set if the returned status is an error.

Returns

Operation result status.

Serialize()

Status kudu::client::KuduScanToken::Serialize

(

std::string *

buf

)

const

Serialize the token into a string.

The resulting string can be deserialized with KuduScanToken::Deserialize() to

Parameters

[out]

buf

Result string to output the serialized token.

Returns

Operation result status.

tablet()

const KuduTablet& kudu::client::KuduScanToken::tablet

(

)

const

Returns

Tablet that this scan will retrieve rows from.

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The documentation for this class was generated from the following file:

• include/kudu/client/client.h