管理数据库连接

本页面提供最佳做法和特定语言的代码示例,帮助您创建高效地使用 Cloud SQL 数据库连接的应用。

这些示例摘自 GitHub 上提供的完整 Web 应用。了解详情

如需了解运行连接到 Cloud SQL 的示例 Web 应用的分步说明,请点击与您的环境所对应的链接:

连接池

连接池是数据库连接的缓存,共享和重复使用缓存中的连接可以缩短连接延迟时间并提高性能。当应用需要使用数据库连接时,它会从连接池中暂借一个,并在用完之后放回池中,供下次需要连接时重复使用。

使用 TCP 连接

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

import os
import ssl

import sqlalchemy


def connect_tcp_socket() -> sqlalchemy.engine.base.Engine:
    """Initializes a TCP connection pool for a Cloud SQL instance of Postgres."""
    # Note: Saving credentials in environment variables is convenient, but not
    # secure - consider a more secure solution such as
    # Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
    # keep secrets safe.
    db_host = os.environ[
        "INSTANCE_HOST"
    ]  # e.g. '127.0.0.1' ('172.17.0.1' if deployed to GAE Flex)
    db_user = os.environ["DB_USER"]  # e.g. 'my-db-user'
    db_pass = os.environ["DB_PASS"]  # e.g. 'my-db-password'
    db_name = os.environ["DB_NAME"]  # e.g. 'my-database'
    db_port = os.environ["DB_PORT"]  # e.g. 5432

    pool = sqlalchemy.create_engine(
        # Equivalent URL:
        # postgresql+pg8000://<db_user>:<db_pass>@<db_host>:<db_port>/<db_name>
        sqlalchemy.engine.url.URL.create(
            drivername="postgresql+pg8000",
            username=db_user,
            password=db_pass,
            host=db_host,
            port=db_port,
            database=db_name,
        ),
        # ...
    )
    return pool

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

注意:

  • CLOUD_SQL_CONNECTION_NAME 应表示为 <MY-PROJECT>:<INSTANCE-REGION>:<INSTANCE-NAME>
  • 使用参数 ipTypes=PRIVATE 将强制 SocketFactory 与实例的关联专用 IP 连接
  • 如需查看 pom.xml 文件的 JDBC 套接字工厂版本的要求,请点击此处


import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import javax.sql.DataSource;

public class TcpConnectionPoolFactory extends ConnectionPoolFactory {

  // Note: Saving credentials in environment variables is convenient, but not
  // secure - consider a more secure solution such as
  // Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
  // keep secrets safe.
  private static final String DB_USER = System.getenv("DB_USER");
  private static final String DB_PASS = System.getenv("DB_PASS");
  private static final String DB_NAME = System.getenv("DB_NAME");

  private static final String INSTANCE_HOST = System.getenv("INSTANCE_HOST");
  private static final String DB_PORT = System.getenv("DB_PORT");


  public static DataSource createConnectionPool() {
    // The configuration object specifies behaviors for the connection pool.
    HikariConfig config = new HikariConfig();

    // The following URL is equivalent to setting the config options below:
    // jdbc:postgresql://<INSTANCE_HOST>:<DB_PORT>/<DB_NAME>?user=<DB_USER>&password=<DB_PASS>
    // See the link below for more info on building a JDBC URL for the Cloud SQL JDBC Socket Factory
    // https://github.com/GoogleCloudPlatform/cloud-sql-jdbc-socket-factory#creating-the-jdbc-url

    // Configure which instance and what database user to connect with.
    config.setJdbcUrl(String.format("jdbc:postgresql://%s:%s/%s", INSTANCE_HOST, DB_PORT, DB_NAME));
    config.setUsername(DB_USER); // e.g. "root", "postgres"
    config.setPassword(DB_PASS); // e.g. "my-password"


    // ... Specify additional connection properties here.
    // ...

    // Initialize the connection pool using the configuration object.
    return new HikariDataSource(config);
  }
}

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

const Knex = require('knex');
const fs = require('fs');

// createTcpPool initializes a TCP connection pool for a Cloud SQL
// instance of Postgres.
const createTcpPool = async config => {
  // Note: Saving credentials in environment variables is convenient, but not
  // secure - consider a more secure solution such as
  // Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
  // keep secrets safe.
  const dbConfig = {
    client: 'pg',
    connection: {
      host: process.env.INSTANCE_HOST, // e.g. '127.0.0.1'
      port: process.env.DB_PORT, // e.g. '5432'
      user: process.env.DB_USER, // e.g. 'my-user'
      password: process.env.DB_PASS, // e.g. 'my-user-password'
      database: process.env.DB_NAME, // e.g. 'my-database'
    },
    // ... Specify additional properties here.
    ...config,
  };
  // Establish a connection to the database.
  return Knex(dbConfig);
};

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

package cloudsql

import (
	"database/sql"
	"fmt"
	"log"
	"os"

	// Note: If connecting using the App Engine Flex Go runtime, use
	// "github.com/jackc/pgx/stdlib" instead, since v5 requires
	// Go modules which are not supported by App Engine Flex.
	_ "github.com/jackc/pgx/v5/stdlib"
)

// connectTCPSocket initializes a TCP connection pool for a Cloud SQL
// instance of Postgres.
func connectTCPSocket() (*sql.DB, error) {
	mustGetenv := func(k string) string {
		v := os.Getenv(k)
		if v == "" {
			log.Fatalf("Fatal Error in connect_tcp.go: %s environment variable not set.", k)
		}
		return v
	}
	// Note: Saving credentials in environment variables is convenient, but not
	// secure - consider a more secure solution such as
	// Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
	// keep secrets safe.
	var (
		dbUser    = mustGetenv("DB_USER")       // e.g. 'my-db-user'
		dbPwd     = mustGetenv("DB_PASS")       // e.g. 'my-db-password'
		dbTCPHost = mustGetenv("INSTANCE_HOST") // e.g. '127.0.0.1' ('172.17.0.1' if deployed to GAE Flex)
		dbPort    = mustGetenv("DB_PORT")       // e.g. '5432'
		dbName    = mustGetenv("DB_NAME")       // e.g. 'my-database'
	)

	dbURI := fmt.Sprintf("host=%s user=%s password=%s port=%s database=%s",
		dbTCPHost, dbUser, dbPwd, dbPort, dbName)


	// dbPool is the pool of database connections.
	dbPool, err := sql.Open("pgx", dbURI)
	if err != nil {
		return nil, fmt.Errorf("sql.Open: %w", err)
	}

	// ...

	return dbPool, nil
}

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

using Npgsql;
using System;

namespace CloudSql
{
    public class PostgreSqlTcp
    {
        public static NpgsqlConnectionStringBuilder NewPostgreSqlTCPConnectionString()
        {
            // Equivalent connection string:
            // "Uid=<DB_USER>;Pwd=<DB_PASS>;Host=<INSTANCE_HOST>;Database=<DB_NAME>;"
            var connectionString = new NpgsqlConnectionStringBuilder()
            {
                // Note: Saving credentials in environment variables is convenient, but not
                // secure - consider a more secure solution such as
                // Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
                // keep secrets safe.
                Host = Environment.GetEnvironmentVariable("INSTANCE_HOST"),     // e.g. '127.0.0.1'
                // Set Host to 'cloudsql' when deploying to App Engine Flexible environment
                Username = Environment.GetEnvironmentVariable("DB_USER"), // e.g. 'my-db-user'
                Password = Environment.GetEnvironmentVariable("DB_PASS"), // e.g. 'my-db-password'
                Database = Environment.GetEnvironmentVariable("DB_NAME"), // e.g. 'my-database'

                // The Cloud SQL proxy provides encryption between the proxy and instance.
                SslMode = SslMode.Disable,
            };
            connectionString.Pooling = true;
            // Specify additional properties here.
            return connectionString;
        }
    }
}

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

tcp: &tcp
  adapter: postgresql
  # Configure additional properties here.
  # Note: Saving credentials in environment variables is convenient, but not
  # secure - consider a more secure solution such as
  # Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
  # keep secrets safe.
  username: <%= ENV["DB_USER"] %>  # e.g. "my-database-user"
  password: <%= ENV["DB_PASS"] %> # e.g. "my-database-password"
  database: <%= ENV.fetch("DB_NAME") { "vote_development" } %>
  host: <%= ENV.fetch("INSTANCE_HOST") { "127.0.0.1" }%> # '172.17.0.1' if deployed to GAE Flex
  port: <%= ENV.fetch("DB_PORT") { 5432 }%>

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

namespace Google\Cloud\Samples\CloudSQL\Postgres;

use PDO;
use PDOException;
use RuntimeException;
use TypeError;

class DatabaseTcp
{
    public static function initTcpDatabaseConnection(): PDO
    {
        try {
            // Note: Saving credentials in environment variables is convenient, but not
            // secure - consider a more secure solution such as
            // Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
            // keep secrets safe.
            $username = getenv('DB_USER'); // e.g. 'your_db_user'
            $password = getenv('DB_PASS'); // e.g. 'your_db_password'
            $dbName = getenv('DB_NAME'); // e.g. 'your_db_name'
            $instanceHost = getenv('INSTANCE_HOST'); // e.g. '127.0.0.1' ('172.17.0.1' for GAE Flex)

            // Connect using TCP
            $dsn = sprintf('pgsql:dbname=%s;host=%s', $dbName, $instanceHost);

            // Connect to the database
            $conn = new PDO(
                $dsn,
                $username,
                $password,
                # ...
            );
        } catch (TypeError $e) {
            throw new RuntimeException(
                sprintf(
                    'Invalid or missing configuration! Make sure you have set ' .
                        '$username, $password, $dbName, and $instanceHost (for TCP mode). ' .
                        'The PHP error was %s',
                    $e->getMessage()
                ),
                $e->getCode(),
                $e
            );
        } catch (PDOException $e) {
            throw new RuntimeException(
                sprintf(
                    'Could not connect to the Cloud SQL Database. Check that ' .
                        'your username and password are correct, that the Cloud SQL ' .
                        'proxy is running, and that the database exists and is ready ' .
                        'for use. For more assistance, refer to %s. The PDO error was %s',
                    'https://cloud.google.com/sql/docs/postgres/connect-external-app',
                    $e->getMessage()
                ),
                $e->getCode(),
                $e
            );
        }

        return $conn;
    }
}

使用 Unix 套接字进行连接

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

import os

import sqlalchemy


def connect_unix_socket() -> sqlalchemy.engine.base.Engine:
    """Initializes a Unix socket connection pool for a Cloud SQL instance of Postgres."""
    # Note: Saving credentials in environment variables is convenient, but not
    # secure - consider a more secure solution such as
    # Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
    # keep secrets safe.
    db_user = os.environ["DB_USER"]  # e.g. 'my-database-user'
    db_pass = os.environ["DB_PASS"]  # e.g. 'my-database-password'
    db_name = os.environ["DB_NAME"]  # e.g. 'my-database'
    unix_socket_path = os.environ[
        "INSTANCE_UNIX_SOCKET"
    ]  # e.g. '/cloudsql/project:region:instance'

    pool = sqlalchemy.create_engine(
        # Equivalent URL:
        # postgresql+pg8000://<db_user>:<db_pass>@/<db_name>
        #                         ?unix_sock=<INSTANCE_UNIX_SOCKET>/.s.PGSQL.5432
        # Note: Some drivers require the `unix_sock` query parameter to use a different key.
        # For example, 'psycopg2' uses the path set to `host` in order to connect successfully.
        sqlalchemy.engine.url.URL.create(
            drivername="postgresql+pg8000",
            username=db_user,
            password=db_pass,
            database=db_name,
            query={"unix_sock": f"{unix_socket_path}/.s.PGSQL.5432"},
        ),
        # ...
    )
    return pool

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import javax.sql.DataSource;

public class ConnectorConnectionPoolFactory extends ConnectionPoolFactory {

  // Note: Saving credentials in environment variables is convenient, but not
  // secure - consider a more secure solution such as
  // Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
  // keep secrets safe.
  private static final String INSTANCE_CONNECTION_NAME =
      System.getenv("INSTANCE_CONNECTION_NAME");
  private static final String INSTANCE_UNIX_SOCKET = System.getenv("INSTANCE_UNIX_SOCKET");
  private static final String DB_USER = System.getenv("DB_USER");
  private static final String DB_PASS = System.getenv("DB_PASS");
  private static final String DB_NAME = System.getenv("DB_NAME");

  public static DataSource createConnectionPool() {
    // The configuration object specifies behaviors for the connection pool.
    HikariConfig config = new HikariConfig();

    // The following URL is equivalent to setting the config options below:
    // jdbc:postgresql:///<DB_NAME>?cloudSqlInstance=<INSTANCE_CONNECTION_NAME>&
    // socketFactory=com.google.cloud.sql.postgres.SocketFactory&user=<DB_USER>&password=<DB_PASS>
    // See the link below for more info on building a JDBC URL for the Cloud SQL JDBC Socket Factory
    // https://github.com/GoogleCloudPlatform/cloud-sql-jdbc-socket-factory#creating-the-jdbc-url

    // Configure which instance and what database user to connect with.
    config.setJdbcUrl(String.format("jdbc:postgresql:///%s", DB_NAME));
    config.setUsername(DB_USER); // e.g. "root", _postgres"
    config.setPassword(DB_PASS); // e.g. "my-password"

    config.addDataSourceProperty("socketFactory", "com.google.cloud.sql.postgres.SocketFactory");
    config.addDataSourceProperty("cloudSqlInstance", INSTANCE_CONNECTION_NAME);

    // Unix sockets are not natively supported in Java, so it is necessary to use the Cloud SQL
    // Java Connector to connect. When setting INSTANCE_UNIX_SOCKET, the connector will 
    // call an external package that will enable Unix socket connections.
    // Note: For Java users, the Cloud SQL Java Connector can provide authenticated connections
    // which is usually preferable to using the Cloud SQL Proxy with Unix sockets.
    // See https://github.com/GoogleCloudPlatform/cloud-sql-jdbc-socket-factory for details.
    if (INSTANCE_UNIX_SOCKET != null) {
      config.addDataSourceProperty("unixSocketPath", INSTANCE_UNIX_SOCKET);
    }



    // ... Specify additional connection properties here.
    // ...

    // Initialize the connection pool using the configuration object.
    return new HikariDataSource(config);
  }
}

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

const Knex = require('knex');

// createUnixSocketPool initializes a Unix socket connection pool for
// a Cloud SQL instance of Postgres.
const createUnixSocketPool = async config => {
  // Note: Saving credentials in environment variables is convenient, but not
  // secure - consider a more secure solution such as
  // Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
  // keep secrets safe.
  return Knex({
    client: 'pg',
    connection: {
      user: process.env.DB_USER, // e.g. 'my-user'
      password: process.env.DB_PASS, // e.g. 'my-user-password'
      database: process.env.DB_NAME, // e.g. 'my-database'
      host: process.env.INSTANCE_UNIX_SOCKET, // e.g. '/cloudsql/project:region:instance'
    },
    // ... Specify additional properties here.
    ...config,
  });
};

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

using Npgsql;
using System;

namespace CloudSql
{
    public class PostgreSqlUnix
    {
        public static NpgsqlConnectionStringBuilder NewPostgreSqlUnixSocketConnectionString()
        {
            // Equivalent connection string:
            // "Server=<INSTANCE_UNIX_SOCKET>;Uid=<DB_USER>;Pwd=<DB_PASS>;Database=<DB_NAME>"
            var connectionString = new NpgsqlConnectionStringBuilder()
            {
                // The Cloud SQL proxy provides encryption between the proxy and instance.
                SslMode = SslMode.Disable,

                // Note: Saving credentials in environment variables is convenient, but not
                // secure - consider a more secure solution such as
                // Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
                // keep secrets safe.
                Host = Environment.GetEnvironmentVariable("INSTANCE_UNIX_SOCKET"), // e.g. '/cloudsql/project:region:instance'
                Username = Environment.GetEnvironmentVariable("DB_USER"), // e.g. 'my-db-user
                Password = Environment.GetEnvironmentVariable("DB_PASS"), // e.g. 'my-db-password'
                Database = Environment.GetEnvironmentVariable("DB_NAME"), // e.g. 'my-database'
            };
            connectionString.Pooling = true;
            // Specify additional properties here.
            return connectionString;
        }
    }
}

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

package cloudsql

import (
	"database/sql"
	"fmt"
	"log"
	"os"

	// Note: If connecting using the App Engine Flex Go runtime, use
	// "github.com/jackc/pgx/stdlib" instead, since v5 requires
	// Go modules which are not supported by App Engine Flex.
	_ "github.com/jackc/pgx/v5/stdlib"
)

// connectUnixSocket initializes a Unix socket connection pool for
// a Cloud SQL instance of Postgres.
func connectUnixSocket() (*sql.DB, error) {
	mustGetenv := func(k string) string {
		v := os.Getenv(k)
		if v == "" {
			log.Fatalf("Fatal Error in connect_unix.go: %s environment variable not set.\n", k)
		}
		return v
	}
	// Note: Saving credentials in environment variables is convenient, but not
	// secure - consider a more secure solution such as
	// Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
	// keep secrets safe.
	var (
		dbUser         = mustGetenv("DB_USER")              // e.g. 'my-db-user'
		dbPwd          = mustGetenv("DB_PASS")              // e.g. 'my-db-password'
		unixSocketPath = mustGetenv("INSTANCE_UNIX_SOCKET") // e.g. '/cloudsql/project:region:instance'
		dbName         = mustGetenv("DB_NAME")              // e.g. 'my-database'
	)

	dbURI := fmt.Sprintf("user=%s password=%s database=%s host=%s",
		dbUser, dbPwd, dbName, unixSocketPath)

	// dbPool is the pool of database connections.
	dbPool, err := sql.Open("pgx", dbURI)
	if err != nil {
		return nil, fmt.Errorf("sql.Open: %w", err)
	}

	// ...

	return dbPool, nil
}

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

unix: &unix
  adapter: postgresql
  # Configure additional properties here.
  # Note: Saving credentials in environment variables is convenient, but not
  # secure - consider a more secure solution such as
  # Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
  # keep secrets safe.
  username: <%= ENV["DB_USER"] %>  # e.g. "my-database-user"
  password: <%= ENV["DB_PASS"] %> # e.g. "my-database-password"
  database: <%= ENV.fetch("DB_NAME") { "vote_development" } %>
  # Specify the Unix socket path as host
  host: "<%= ENV["INSTANCE_UNIX_SOCKET"] %>"

如需了解 Web 应用环境下的此代码段,请查看 GitHub 上的 README

namespace Google\Cloud\Samples\CloudSQL\Postgres;

use PDO;
use PDOException;
use RuntimeException;
use TypeError;

class DatabaseUnix
{
    public static function initUnixDatabaseConnection(): PDO
    {
        try {
            // Note: Saving credentials in environment variables is convenient, but not
            // secure - consider a more secure solution such as
            // Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
            // keep secrets safe.
            $username = getenv('DB_USER'); // e.g. 'your_db_user'
            $password = getenv('DB_PASS'); // e.g. 'your_db_password'
            $dbName = getenv('DB_NAME'); // e.g. 'your_db_name'
            $instanceUnixSocket = getenv('INSTANCE_UNIX_SOCKET'); // e.g. '/cloudsql/project:region:instance'

            // Connect using UNIX sockets
            $dsn = sprintf(
                'pgsql:dbname=%s;host=%s',
                $dbName,
                $instanceUnixSocket
            );

            // Connect to the database.
            $conn = new PDO(
                $dsn,
                $username,
                $password,
                # ...
            );
        } catch (TypeError $e) {
            throw new RuntimeException(
                sprintf(
                    'Invalid or missing configuration! Make sure you have set ' .
                        '$username, $password, $dbName, ' .
                        'and $instanceUnixSocket (for UNIX socket mode). ' .
                        'The PHP error was %s',
                    $e->getMessage()
                ),
                (int) $e->getCode(),
                $e
            );
        } catch (PDOException $e) {
            throw new RuntimeException(
                sprintf(
                    'Could not connect to the Cloud SQL Database. Check that ' .
                        'your username and password are correct, that the Cloud SQL ' .
                        'proxy is running, and that the database exists and is ready ' .
                        'for use. For more assistance, refer to %s. The PDO error was %s',
                    'https://cloud.google.com/sql/docs/postgres/connect-external-app',
                    $e->getMessage()
                ),
                (int) $e->getCode(),
                $e
            );
        }

        return $conn;
    }
}

打开和关闭连接

使用连接池时必须正确地打开和关闭连接,以便在用完连接后始终将其放回池中。未放回(也称为“外泄”)的连接无法重复使用,会造成资源浪费并可能导致应用出现性能瓶颈。

# Preparing a statement before hand can help protect against injections.
stmt = sqlalchemy.text(
    "INSERT INTO votes (time_cast, candidate) VALUES (:time_cast, :candidate)"
)
try:
    # Using a with statement ensures that the connection is always released
    # back into the pool at the end of statement (even if an error occurs)
    with db.connect() as conn:
        conn.execute(stmt, parameters={"time_cast": time_cast, "candidate": team})
        conn.commit()
except Exception as e:
    # If something goes wrong, handle the error in this section. This might
    # involve retrying or adjusting parameters depending on the situation.
    # ...
// Using a try-with-resources statement ensures that the connection is always released back
// into the pool at the end of the statement (even if an error occurs)
try (Connection conn = pool.getConnection()) {

  // PreparedStatements can be more efficient and project against injections.
  String stmt = "INSERT INTO votes (time_cast, candidate) VALUES (?, ?);";
  try (PreparedStatement voteStmt = conn.prepareStatement(stmt);) {
    voteStmt.setTimestamp(1, now);
    voteStmt.setString(2, team);

    // Finally, execute the statement. If it fails, an error will be thrown.
    voteStmt.execute();
  }
} catch (SQLException ex) {
  // If something goes wrong, handle the error in this section. This might involve retrying or
  // adjusting parameters depending on the situation.
  // ...
}
/**
 * Insert a vote record into the database.
 *
 * @param {object} pool The Knex connection object.
 * @param {object} vote The vote record to insert.
 * @returns {Promise}
 */
const insertVote = async (pool, vote) => {
  try {
    return await pool('votes').insert(vote);
  } catch (err) {
    throw Error(err);
  }
};
using Npgsql;
using System;

namespace CloudSql
{
    public class PostgreSqlTcp
    {
        public static NpgsqlConnectionStringBuilder NewPostgreSqlTCPConnectionString()
        {
            // Equivalent connection string:
            // "Uid=<DB_USER>;Pwd=<DB_PASS>;Host=<INSTANCE_HOST>;Database=<DB_NAME>;"
            var connectionString = new NpgsqlConnectionStringBuilder()
            {
                // Note: Saving credentials in environment variables is convenient, but not
                // secure - consider a more secure solution such as
                // Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
                // keep secrets safe.
                Host = Environment.GetEnvironmentVariable("INSTANCE_HOST"),     // e.g. '127.0.0.1'
                // Set Host to 'cloudsql' when deploying to App Engine Flexible environment
                Username = Environment.GetEnvironmentVariable("DB_USER"), // e.g. 'my-db-user'
                Password = Environment.GetEnvironmentVariable("DB_PASS"), // e.g. 'my-db-password'
                Database = Environment.GetEnvironmentVariable("DB_NAME"), // e.g. 'my-database'

                // The Cloud SQL proxy provides encryption between the proxy and instance.
                SslMode = SslMode.Disable,
            };
            connectionString.Pooling = true;
            // Specify additional properties here.
            return connectionString;
        }
    }
}
insertVote := "INSERT INTO votes(candidate, created_at) VALUES($1, NOW())"
_, err := db.Exec(insertVote, team)
@vote = Vote.new candidate: candidate

# ActiveRecord creates and executes your SQL and automatically
# handles the opening and closing of the database connection.
if @vote.save
  render json: "Vote successfully cast for \"#{@vote.candidate}\" at #{@vote.time_cast} PST!"
else
  render json: @vote.errors, status: :unprocessable_entity
end
// Use prepared statements to guard against SQL injection.
$sql = 'INSERT INTO votes (time_cast, candidate) VALUES (NOW(), :voteValue)';

try {
    $statement = $conn->prepare($sql);
    $statement->bindParam('voteValue', $value);

    $res = $statement->execute();
} catch (PDOException $e) {
    throw new RuntimeException(
        'Could not insert vote into database. The PDO exception was ' .
        $e->getMessage(),
        $e->getCode(),
        $e
    );
}

连接数

每个数据库连接都会使用客户端和服务器端资源。此外,Cloud SQL 存在一个不能超出的总连接数量限制。创建和使用的连接越少,开销就越低,还有助于确保不超过连接数上限。

# Pool size is the maximum number of permanent connections to keep.
pool_size=5,
# Temporarily exceeds the set pool_size if no connections are available.
max_overflow=2,
# The total number of concurrent connections for your application will be
# a total of pool_size and max_overflow.
// maximumPoolSize limits the total number of concurrent connections this pool will keep. Ideal
// values for this setting are highly variable on app design, infrastructure, and database.
config.setMaximumPoolSize(5);
// minimumIdle is the minimum number of idle connections Hikari maintains in the pool.
// Additional connections will be established to meet this value unless the pool is full.
config.setMinimumIdle(5);
// 'max' limits the total number of concurrent connections this pool will keep. Ideal
// values for this setting are highly variable on app design, infrastructure, and database.
config.pool.max = 5;
// 'min' is the minimum number of idle connections Knex maintains in the pool.
// Additional connections will be established to meet this value unless the pool is full.
config.pool.min = 5;
// MaxPoolSize sets maximum number of connections allowed in the pool.
connectionString.MaxPoolSize = 5;
// MinPoolSize sets the minimum number of connections in the pool.
connectionString.MinPoolSize = 0;
// Set maximum number of connections in idle connection pool.
db.SetMaxIdleConns(5)

// Set maximum number of open connections to the database.
db.SetMaxOpenConns(7)
# 'pool' is the maximum number of permanent connections to keep.
pool: 5

PDO 目前不提供任何功能来配置连接限制。

指数退避算法

如果您的应用尝试连接到数据库但未成功,则表示数据库可能暂时不可用。在这种情况下,发送重复的连接请求会浪费资源。最好等待一段时间后再发送其他连接请求,留出时间让数据库再次可供访问。使用指数退避算法或其他延迟机制来实现此目标。

只有在首次连接或首次从池中获取连接时,这种重试才有意义。如果错误发生在事务的中间,应用必须执行重试,并且必须从事务的开始重试。因此,即使您的池配置正确,如果连接丢失,应用仍可能会遇到错误。

# SQLAlchemy automatically uses delays between failed connection attempts,
# but provides no arguments for configuration.
// Hikari automatically delays between failed connection attempts, eventually reaching a
// maximum delay of `connectionTimeout / 2` between attempts.
// 'knex' uses a built-in retry strategy which does not implement backoff.
// 'createRetryIntervalMillis' is how long to idle after failed connection creation before trying again
config.pool.createRetryIntervalMillis = 200; // 0.2 seconds
Policy
    .Handle<NpgsqlException>()
    .WaitAndRetry(new[]
    {
        TimeSpan.FromSeconds(1),
        TimeSpan.FromSeconds(2),
        TimeSpan.FromSeconds(5)
    })
    .Execute(() => connection.Open());

database/sql 软件包目前未提供任何用于配置指数退避算法的功能。

# ActiveRecord automatically uses delays between failed connection attempts,
# but provides no arguments for configuration.

PDO 目前未提供任何用于配置指数退避算法的功能。

连接超时

尝试连接时失败的原因有很多。可能是网络通信出了问题,也可能是数据库暂时无法响应。请确保您的应用可以正常处理连接中断或连接失败的情况。

# 'pool_timeout' is the maximum number of seconds to wait when retrieving a
# new connection from the pool. After the specified amount of time, an
# exception will be thrown.
pool_timeout=30,  # 30 seconds
// setConnectionTimeout is the maximum number of milliseconds to wait for a connection checkout.
// Any attempt to retrieve a connection from this pool that exceeds the set limit will throw an
// SQLException.
config.setConnectionTimeout(10000); // 10 seconds
// idleTimeout is the maximum amount of time a connection can sit in the pool. Connections that
// sit idle for this many milliseconds are retried if minimumIdle is exceeded.
config.setIdleTimeout(600000); // 10 minutes
// 'acquireTimeoutMillis' is the number of milliseconds before a timeout occurs when acquiring a
// connection from the pool. This is slightly different from connectionTimeout, because acquiring
// a pool connection does not always involve making a new connection, and may include multiple retries.
// when making a connection
config.pool.acquireTimeoutMillis = 60000; // 60 seconds
// 'createTimeoutMillis` is the maximum number of milliseconds to wait trying to establish an
// initial connection before retrying.
// After acquireTimeoutMillis has passed, a timeout exception will be thrown.
config.pool.createTimeoutMillis = 30000; // 30 seconds
// 'idleTimeoutMillis' is the number of milliseconds a connection must sit idle in the pool
// and not be checked out before it is automatically closed.
config.pool.idleTimeoutMillis = 600000; // 10 minutes
// Timeout sets the time to wait (in seconds) while
// trying to establish a connection before terminating the attempt.
connectionString.Timeout = 15;

database/sql 软件包目前不提供任何用来配置连接超时的功能。在驱动程序级别配置超时。

# 'timeout' is the maximum number of seconds to wait when retrieving a
# new connection from the pool. After the specified amount of time, an
# ActiveRecord::ConnectionTimeoutError will be raised.
timeout: 5000
// Here we set the connection timeout to five seconds and ask PDO to
// throw an exception if any errors occur.
[
    PDO::ATTR_TIMEOUT => 5,
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
]

连接时长

限制连接的生命周期长度有助于防止被抛弃的连接不断累加。您可以使用连接池来限制连接的生命周期。

# 'pool_recycle' is the maximum number of seconds a connection can persist.
# Connections that live longer than the specified amount of time will be
# re-established
pool_recycle=1800,  # 30 minutes
// maxLifetime is the maximum possible lifetime of a connection in the pool. Connections that
// live longer than this many milliseconds will be closed and reestablished between uses. This
// value should be several minutes shorter than the database's timeout value to avoid unexpected
// terminations.
config.setMaxLifetime(1800000); // 30 minutes

knex”Node.js 库目前未提供任何功能来控制连接时长。

// ConnectionIdleLifetime sets the time (in seconds) to wait before
// closing idle connections in the pool if the count of all
// connections exceeds MinPoolSize.
connectionString.ConnectionIdleLifetime = 300;
// Set Maximum time (in seconds) that a connection can remain open.
db.SetConnMaxLifetime(1800 * time.Second)

ActiveRecord 目前未提供任何功能来控制连接时长。

PDO 目前未提供任何功能来控制连接时长。

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