MongoDB\Collection::explain()

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Definition

Parameters
Return Values
Errors/Exceptions
Explainable Commands
Examples
See Also

New in version 1.4.

Definition

MongoDB\Collection::explain()

Explain the given command.

function explain(
    MongoDB\Operation\Explainable $explainable,
    array $options = []
): array|object

Parameters

$explainable : MongoDB\Operation\Explainable

The command to explain.

$options : array

An array specifying the desired options.

Name	Type	Description
comment	mixed	Enables users to specify an arbitrary comment to help trace the operation through the database profiler, currentOp output, and logs. This option is available since MongoDB 4.4 and will result in an exception at execution time if specified for an older server version. Defaults to the `comment` of the explained operation (if any). New in version 1.13.
readPreference	MongoDB\Driver\ReadPreference	Read preference to use for the operation. Defaults to the collection's read preference.
typeMap	array	The type map to apply to cursors, which determines how BSON documents are converted to PHP values. Defaults to the collection's type map. This will be used for the returned command result document.
verbosity	string	The verbosity level at which to run the command. See the explain command for more information.

Return Values

An array or object with the result document of the explain command. The return type will depend on the typeMap option.

Errors/Exceptions

MongoDB\Exception\UnsupportedException if options are used and not supported by the selected server (e.g. collation, readConcern, writeConcern).

MongoDB\Exception\InvalidArgumentException for errors related to the parsing of parameters or options.

MongoDB\Driver\Exception\RuntimeException for other errors at the driver level (e.g. connection errors).

Explainable Commands

Explainable commands include, but are not limited to:

MongoDB\Operation\Aggregate
MongoDB\Operation\Count
MongoDB\Operation\DeleteMany
MongoDB\Operation\DeleteOne
MongoDB\Operation\Distinct
MongoDB\Operation\Find
MongoDB\Operation\FindOne
MongoDB\Operation\FindOneAndDelete
MongoDB\Operation\FindOneAndReplace
MongoDB\Operation\FindOneAndUpdate
MongoDB\Operation\UpdateMany
MongoDB\Operation\UpdateOne

Examples

This example explains a count command.

<?php
$collection = (new MongoDB\Client)->test->restaurants;
$count = new MongoDB\Operation\Count(
    $collection->getDatabaseName(),
    $collection->getCollectionName(),
    ['cuisine' => 'Italian']
);
$result = $collection->explain($count);
var_dump($result);

The output would then resemble:

object(MongoDB\Model\BSONDocument)#29 (1) {
  ["storage":"ArrayObject":private]=>
  array(4) {
    ["queryPlanner"]=>
    object(MongoDB\Model\BSONDocument)#21 (1) {
      ["storage":"ArrayObject":private]=>
      array(6) {
        ["plannerVersion"]=>
        int(1)
        ["namespace"]=>
        string(16) "test.restaurants"
        ["indexFilterSet"]=>
        bool(false)
        ["parsedQuery"]=>
        object(MongoDB\Model\BSONDocument)#15 (1) {
          ["storage":"ArrayObject":private]=>
          array(1) {
            ["cuisine"]=>
            object(MongoDB\Model\BSONDocument)#14 (1) {
              ["storage":"ArrayObject":private]=>
              array(1) {
                ["$eq"]=>
                string(7) "Italian"
              }
            }
          }
        }
        ["winningPlan"]=>
        object(MongoDB\Model\BSONDocument)#19 (1) {
          ["storage":"ArrayObject":private]=>
          array(2) {
            ["stage"]=>
            string(5) "COUNT"
            ["inputStage"]=>
            object(MongoDB\Model\BSONDocument)#18 (1) {
              ["storage":"ArrayObject":private]=>
              array(3) {
                ["stage"]=>
                string(8) "COLLSCAN"
                ["filter"]=>
                object(MongoDB\Model\BSONDocument)#17 (1) {
                  ["storage":"ArrayObject":private]=>
                  array(1) {
                    ["cuisine"]=>
                    object(MongoDB\Model\BSONDocument)#16 (1) {
                      ["storage":"ArrayObject":private]=>
                      array(1) {
                        ["$eq"]=>
                        string(7) "Italian"
                      }
                    }
                  }
                }
                ["direction"]=>
                string(7) "forward"
              }
            }
          }
        }
        ["rejectedPlans"]=>
        object(MongoDB\Model\BSONArray)#20 (1) {
          ["storage":"ArrayObject":private]=>
          array(0) {
          }
        }
      }
    }
    ["executionStats"]=>
    object(MongoDB\Model\BSONDocument)#27 (1) {
      ["storage":"ArrayObject":private]=>
      array(7) {
        ["executionSuccess"]=>
        bool(true)
        ["nReturned"]=>
        int(0)
        ["executionTimeMillis"]=>
        int(24)
        ["totalKeysExamined"]=>
        int(0)
        ["totalDocsExamined"]=>
        int(25359)
        ["executionStages"]=>
        object(MongoDB\Model\BSONDocument)#25 (1) {
          ["storage":"ArrayObject":private]=>
          array(14) {
            ["stage"]=>
            string(5) "COUNT"
            ["nReturned"]=>
            int(0)
            ["executionTimeMillisEstimate"]=>
            int(20)
            ["works"]=>
            int(25361)
            ["advanced"]=>
            int(0)
            ["needTime"]=>
            int(25360)
            ["needYield"]=>
            int(0)
            ["saveState"]=>
            int(198)
            ["restoreState"]=>
            int(198)
            ["isEOF"]=>
            int(1)
            ["invalidates"]=>
            int(0)
            ["nCounted"]=>
            int(1069)
            ["nSkipped"]=>
            int(0)
            ["inputStage"]=>
            object(MongoDB\Model\BSONDocument)#24 (1) {
              ["storage":"ArrayObject":private]=>
              array(14) {
                ["stage"]=>
                string(8) "COLLSCAN"
                ["filter"]=>
                object(MongoDB\Model\BSONDocument)#23 (1) {
                  ["storage":"ArrayObject":private]=>
                  array(1) {
                    ["cuisine"]=>
                    object(MongoDB\Model\BSONDocument)#22 (1) {
                      ["storage":"ArrayObject":private]=>
                      array(1) {
                        ["$eq"]=>
                        string(7) "Italian"
                      }
                    }
                  }
                }
                ["nReturned"]=>
                int(1069)
                ["executionTimeMillisEstimate"]=>
                int(20)
                ["works"]=>
                int(25361)
                ["advanced"]=>
                int(1069)
                ["needTime"]=>
                int(24291)
                ["needYield"]=>
                int(0)
                ["saveState"]=>
                int(198)
                ["restoreState"]=>
                int(198)
                ["isEOF"]=>
                int(1)
                ["invalidates"]=>
                int(0)
                ["direction"]=>
                string(7) "forward"
                ["docsExamined"]=>
                int(25359)
              }
            }
          }
        }
        ["allPlansExecution"]=>
        object(MongoDB\Model\BSONArray)#26 (1) {
          ["storage":"ArrayObject":private]=>
          array(0) {
          }
        }
      }
    }
    ["serverInfo"]=>
    object(MongoDB\Model\BSONDocument)#28 (1) {
      ["storage":"ArrayObject":private]=>
      array(4) {
        ["host"]=>
        string(9) "localhost"
        ["port"]=>
        int(27017)
        ["version"]=>
        string(5) "3.6.1"
        ["gitVersion"]=>
        string(40) "025d4f4fe61efd1fb6f0005be20cb45a004093d1"
      }
    }
    ["ok"]=>
    float(1)
  }
}