Golang

Pinot Client for Golang

Pinot provides a native Go client to query database directly from go application.

Install

1. Follow this Pinot quickstart link to install and start Pinot locally.

bin/quick-start-batch.sh

1. Check out the client library GitHub repository.

git clone [e-mail]:startreedata/pinot-client-go.git
cd pinot-client-go

1. Build and run the example application to query from the Pinot batch quickstart.

go build ./examples/batch-quickstart
./batch-quickstart

Use the Golang client

Create a Pinot connection

Initialize the Pinot client using one of the methods below.

Zookeeper Path

pinotClient := pinot.NewFromZookeeper([]string{"localhost:2123"}, "", "QuickStartCluster")

List of broker addresses

pinotClient := pinot.NewFromBrokerList([]string{"localhost:8000"})

ClientConfig

pinotClient := pinot.NewWithConfig(&pinot.ClientConfig{
	ZkConfig: &pinot.ZookeeperConfig{
		ZookeeperPath:     zkPath,
		PathPrefix:        strings.Join([]string{zkPathPrefix, pinotCluster}, "/"),
		SessionTimeoutSec: defaultZkSessionTimeoutSec,
	},
    ExtraHTTPHeader: map[string]string{
        "extra-header":"value",
    },
})

Query Pinot

The Go client repository contains an example script.

Code snippet:

pinotClient, err := pinot.NewFromZookeeper([]string{"localhost:2123"}, "", "QuickStartCluster")
if err != nil {
    log.Error(err)
}
brokerResp, err := pinotClient.ExecuteSQL("baseballStats", "select count(*) as cnt, sum(homeRuns) as sum_homeRuns from baseballStats group by teamID limit 10")
if err != nil {
    log.Error(err)
}
log.Infof("Query Stats: response time - %d ms, scanned docs - %d, total docs - %d", brokerResp.TimeUsedMs, brokerResp.NumDocsScanned, brokerResp.TotalDocs)

Response format

The query response has the following format:

type BrokerResponse struct {
	AggregationResults          []*AggregationResult `json:"aggregationResults,omitempty"`
	SelectionResults            *SelectionResults    `json:"SelectionResults,omitempty"`
	ResultTable                 *ResultTable         `json:"resultTable,omitempty"`
	Exceptions                  []Exception          `json:"exceptions"`
	TraceInfo                   map[string]string    `json:"traceInfo,omitempty"`
	NumServersQueried           int                  `json:"numServersQueried"`
	NumServersResponded         int                  `json:"numServersResponded"`
	NumSegmentsQueried          int                  `json:"numSegmentsQueried"`
	NumSegmentsProcessed        int                  `json:"numSegmentsProcessed"`
	NumSegmentsMatched          int                  `json:"numSegmentsMatched"`
	NumConsumingSegmentsQueried int                  `json:"numConsumingSegmentsQueried"`
	NumDocsScanned              int64                `json:"numDocsScanned"`
	NumEntriesScannedInFilter   int64                `json:"numEntriesScannedInFilter"`
	NumEntriesScannedPostFilter int64                `json:"numEntriesScannedPostFilter"`
	NumGroupsLimitReached       bool                 `json:"numGroupsLimitReached"`
	TotalDocs                   int64                `json:"totalDocs"`
	TimeUsedMs                  int                  `json:"timeUsedMs"`
	MinConsumingFreshnessTimeMs int64                `json:"minConsumingFreshnessTimeMs"`
}

Note that AggregationResults and SelectionResults are holders for Pinot query language (PQL) queries.

Meanwhile, ResultTable is the holder for SQL queries. ResultTable is defined as:

// ResultTable is a ResultTable
type ResultTable struct {
	DataSchema RespSchema      `json:"dataSchema"`
	Rows       [][]interface{} `json:"rows"`
}

RespSchema is defined as:

// RespSchema is response schema
type RespSchema struct {
	ColumnDataTypes []string `json:"columnDataTypes"`
	ColumnNames     []string `json:"columnNames"`
}

There are multiple functions defined for ResultTable, such as the following:

func (r ResultTable) GetRowCount() int
func (r ResultTable) GetColumnCount() int
func (r ResultTable) GetColumnName(columnIndex int) string
func (r ResultTable) GetColumnDataType(columnIndex int) string
func (r ResultTable) Get(rowIndex int, columnIndex int) interface{}
func (r ResultTable) GetString(rowIndex int, columnIndex int) string
func (r ResultTable) GetInt(rowIndex int, columnIndex int) int
func (r ResultTable) GetLong(rowIndex int, columnIndex int) int64
func (r ResultTable) GetFloat(rowIndex int, columnIndex int) float32
func (r ResultTable) GetDouble(rowIndex int, columnIndex int) float64

See an example of a function in use here and below:

// Print Response Schema
for c := 0; c < brokerResp.ResultTable.GetColumnCount(); c++ {
  fmt.Printf("%s(%s)\t", brokerResp.ResultTable.GetColumnName(c), brokerResp.ResultTable.GetColumnDataType(c))
}
fmt.Println()

// Print Row Table
for r := 0; r < brokerResp.ResultTable.GetRowCount(); r++ {
  for c := 0; c < brokerResp.ResultTable.GetColumnCount(); c++ {
    fmt.Printf("%v\t", brokerResp.ResultTable.Get(r, c))
  }
  fmt.Println()
}