Implementing a Go drive for Neo

📌

For smooth practice, the following query should be run to prepare tables and data.

CREATE TAG TABLE IF NOT EXISTS EXAMPLE (
    NAME VARCHAR(20) PRIMARY KEY,
    TIME DATETIME BASETIME,
    VALUE DOUBLE SUMMARIZED
);

Go provides database/sql package you can incorporate a wide variety of databases and data access in your applications.

This tutorial gives an introductory guide to access machbase-neo with database/sql package in Go.

Find full source code from github

Install

Tp add driver into your go.mod, execute this command on your working directory.

go get -u github.com/machbase/neo-grpc/driver

Import

Add import statement in your source file.

import (
    "database/sql"
    _ "github.com/machbase/neo-grpc/driver"
)

The package name github.com/machbase/neo-grpc/driver implies that the driver is implemented over gRPC API of machbase-neo. See gRPC API for more about it.

Let’s load sql driver and connect to server.

db, err := sql.Open("machbase", "127.0.0.1:5655")
if err != nil {
    panic(err)
}
defer db.Close()

sql.Open() is called, machbase as driverName and second argument is machbase-neo’s gRPC address.

Insert and Query

Since we get *sql.DB successfully, write and read data can be done by Go standard sql package.

var tag = "tag01"
_, err = db.Exec("INSERT INTO EXAMPLE (name, time, value) VALUES(?, ?, ?)", tag, time.Now(), 1.234)

Use db.QueryRow() to count total records of same tag name.

var count int
row := db.QueryRow("SELECT count(*) FROM EXAMPLE WHERE name = ?", tag)
row.Scan(&count)

To iterate result of query, use db.Query() and get *sql.Rows.

⚠️

It is import not to forget releasing rows as soon as possible when you finish the work to prevent leaking resource.
General pattern is using defer rows.Close().

rows, err := db.Query("SELECT name, time, value FROM EXAMPLE WHERE name = ? ORDER BY TIME DESC", tag)
if err != nil {
    panic(err)
}
defer rows.Close()

for rows.Next() {
    var name string
    var ts time.Time
    var value float64
    rows.Scan(&name, &ts, &value)
    fmt.Println("name:", name, "time:", ts.Local().String(), "value:", value)
}

Last updated on Sep 27, 2023

How to communicate with Neo via gRPC in Go