Paginate Eloquent query using SQL_CALC_FOUND_ROWS and FOUND_ROWS() — avoids running the query twice

fast_paginate.php

<?php

function paginateOptimized(Builder $builder, $perPage = null, $pageName = 'page', $page = null): LengthAwarePaginator
{
    $model = $builder->getModel();

    $page = $page ?: Paginator::resolveCurrentPage($pageName);
    $perPage = $perPage ?: $model->getPerPage();

    $sql = $builder->forPage($page, $perPage)->toSql();

    if (!starts_with($sql, 'select ')) {
        throw new \Exception('SELECT statement expected to start with "select "');
    }

    // Insert SQL_CALC_FOUND_ROWS option
    $sql = substr_replace($sql, ' sql_calc_found_rows', 6, 0);

    $rows = DB::select($sql, $builder->getBindings());

    // Get the calculated total count using FOUND_ROWS()
    $total = DB::selectOne('select found_rows() as total')->total;

    $models = $model->hydrate($rows)->all();

    if (count($models) > 0) {
        $models = $builder->eagerLoadRelations($models);
    }

    $models = $model->newCollection($models);

    return new LengthAwarePaginator($models, $total, $perPage, $page, [
        'pageName' => $pageName,
        'path'     => Paginator::resolveCurrentPath(),
    ]);
}