PostgreSQL

/*

** Zabbix

** Copyright 2001-2024 Zabbix SIA

**

** Licensed under the Apache License, Version 2.0 (the "License");

** you may not use this file except in compliance with the License.

** You may obtain a copy of the License at

**

**     http://www.apache.org/licenses/LICENSE-2.0

**

** Unless required by applicable law or agreed to in writing, software

** distributed under the License is distributed on an "AS IS" BASIS,

** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

** See the License for the specific language governing permissions and

** limitations under the License.

**/

​

package plugin

​

import (

    "context"

    "errors"

​

    "git.zabbix.com/ap/plugin-support/zbxerr"

    "github.com/jackc/pgx/v4"

)

​

// bgwriterHandler executes select  with statistics from pg_stat_bgwriter

// and returns JSON if all is OK or nil otherwise.

func bgwriterHandler(ctx context.Context, conn PostgresClient,

    _ string, _ map[string]string, _ ...string) (interface{}, error) {

    var bgwriterJSON string

​

    query := `

  SELECT row_to_json (T)

    FROM (

          SELECT

              checkpoints_timed

            , checkpoints_req

            , checkpoint_write_time

            , checkpoint_sync_time

            , buffers_checkpoint

            , buffers_clean

            , maxwritten_clean

            , buffers_backend

            , buffers_backend_fsync

            , buffers_alloc

          FROM pg_catalog.pg_stat_bgwriter

          ) T ;`

​

    row, err := conn.QueryRow(ctx, query)

    if err != nil {

        return nil, zbxerr.ErrorCannotFetchData.Wrap(err)

    }

​

    err = row.Scan(&bgwriterJSON)

    if err != nil {

        if errors.Is(err, pgx.ErrNoRows) {

            return nil, zbxerr.ErrorEmptyResult.Wrap(err)

        }

​

        return nil, zbxerr.ErrorCannotFetchData.Wrap(err)

    }