Interaction between Golang functions and distributed databases in distributed systems

In a distributed system, Go functions can interact with distributed databases. The specific steps are as follows: Install the necessary dependencies. Use the spanner.NewClient function to connect to the database. Use the Query method to execute the query and get the iterator. Use the Do method to iterate through the query results and process the data. After the query is complete, use the Close method to close the connection.

Interaction between Go functions and distributed databases in distributed systems

In distributed systems, it is a common requirement for Go functions to interact with distributed databases. This article guides you through using Go code to connect to and query a distributed database.

Install dependencies

The first step is to install the necessary dependencies:

import (
    "context"
    "fmt"
    "log"

    "cloud.google.com/go/spanner"
)

Connect to the database

To connect to the database, use spanner.NewClient Function:

client, err := spanner.NewClient(context.Background(), "projects/my-project", "instances/my-instance", "databases/my-database")
if err != nil {
    log.Fatal(err)
}

Execute query

To execute a query, use Query Method:

stmt := spanner.Statement{SQL: `SELECT * FROM Singers`}
iter := client.Single().Query(context.Background(), stmt)
defer iter.Stop()

iter is an iterator that will iterate over the query results.

Processing the results

To process the results, please use the Do method:

for {
    row, err := iter.Next()
    if err == iterator.Done {
        break
    }
    if err != nil {
        log.Fatal(err)
    }
    var singerId int64
    var firstName string
    var lastName string
    if err := row.ColumnByName("SingerId", &singerId); err != nil {
        log.Fatal(err)
    }
    if err := row.ColumnByName("FirstName", &firstName); err != nil {
        log.Fatal(err)
    }
    if err := row.ColumnByName("LastName", &lastName); err != nil {
        log.Fatal(err)
    }
    fmt.Printf("%d %s %s\n", singerId, firstName, lastName)
}

Close the connection

After the query is completed, please close Connection to the database:

client.Close()

Practical case

The following is a complete Go code example showing how to connect to the Cloud Spanner database and execute queries:

package main

import (
    "context"
    "fmt"
    "log"

    "cloud.google.com/go/spanner"
)

func main() {
    client, err := spanner.NewClient(context.Background(), "projects/my-project", "instances/my-instance", "databases/my-database")
    if err != nil {
        log.Fatal(err)
    }
    defer client.Close()

    stmt := spanner.Statement{SQL: `SELECT * FROM Singers`}
    iter := client.Single().Query(context.Background(), stmt)
    defer iter.Stop()

    for {
        row, err := iter.Next()
        if err == iterator.Done {
            break
        }
        if err != nil {
            log.Fatal(err)
        }
        var singerId int64
        var firstName string
        var lastName string
        if err := row.ColumnByName("SingerId", &singerId); err != nil {
            log.Fatal(err)
        }
        if err := row.ColumnByName("FirstName", &firstName); err != nil {
            log.Fatal(err)
        }
        if err := row.ColumnByName("LastName", &lastName); err != nil {
            log.Fatal(err)
        }
        fmt.Printf("%d %s %s\n", singerId, firstName, lastName)
    }
}

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