Golang Apache Impala Driver

Apache Impala driver for Go's database/sql package

This driver started as a fork of github.com/bippio/go-impala, which hasn't been updated in over four years and appears to be abandoned. After fork, several issues have been fixed.

The current implementation of the driver is based on the Hive Server 2 protocol. Issues and contributions are welcome.

Install

go get github.com/sclgo/impala

Connection Parameters and DSN

The connection string uses a URL format: impala://username:password@host:port?param1=value&param2=value

Parameters:

• auth - string. Authentication mode. Supported values: "noauth", "ldap"
• tls - boolean. Enable TLS
• ca-cert - The file that contains the public key certificate of the CA that signed the impala certificate
• batch-size - integer value (default: 1024). Maximum number of rows fetched per request
• buffer-size- in bytes (default: 4096); Buffer size for the Thrift transport
• mem-limit - string value (example: 3m); Memory limit for query

A string of this format can be constructed using the URL type in the net/url package.

  query := url.Values{}
  query.Add("auth", "ldap")

  u := &url.URL{
      Scheme:   "impala",
      User:     url.UserPassword(username, password),
      Host:     net.JoinHostPort(hostname, port),
      RawQuery: query.Encode(),
  }
  db, err := sql.Open("impala", u.String())

Also, you can bypass string-base data source name by using sql.OpenDB:

  opts := impala.DefaultOptions
  opts.Host = hostname
  opts.UseLDAP = true
  opts.Username = username
  opts.Password = password

  connector := impala.NewConnector(&opts)
  db := sql.OpenDB(connector)

Example

package main

// Simple program to list databases and the tables

import (
	"context"
	"database/sql"
	"log"

	"github.com/sclgo/impala"
)

func main() {

	opts := impala.DefaultOptions

	opts.Host = "<impala host>"
	opts.Port = "21050"

	// enable LDAP authentication:
	opts.UseLDAP = true
	opts.Username = "<ldap username>"
	opts.Password = "<ldap password>"

	// enable TLS
	opts.UseTLS = true
	opts.CACertPath = "/path/to/cacert"

	connector := impala.NewConnector(&opts)
	db := sql.OpenDB(connector)
	defer db.Close()

	ctx := context.Background()

	rows, err := db.QueryContext(ctx, "SHOW DATABASES")
	if err != nil {
		log.Fatal(err)
	}

	r := struct {
		name    string
		comment string
	}{}

	databases := make([]string, 0) // databases will contain all the DBs to enumerate later
	for rows.Next() {
		if err := rows.Scan(&r.name, &r.comment); err != nil {
			log.Fatal(err)
		}
		databases = append(databases, r.name)
	}
	if err := rows.Err(); err != nil {
		log.Fatal(err)
	}
	log.Println("List of Databases", databases)

	stmt, err := db.PrepareContext(ctx, "SHOW TABLES IN ?")
	if err != nil {
		log.Fatal(err)
	}

	tbl := struct {
		name string
	}{}

	for _, d := range databases {
		rows, err := stmt.QueryContext(ctx, d)
		if err != nil {
			log.Printf("error in querying database %s: %s", d, err.Error())
			continue
		}

		tables := make([]string, 0)
		for rows.Next() {
			if err := rows.Scan(&tbl.name); err != nil {
				log.Println(err)
				continue
			}
			tables = append(tables, tbl.name)
		}
		log.Printf("List of Tables in Database %s: %v\n", d, tables)
	}
}