MongoDB\Collection::explain()

New in version 1.4.

On this page

Definition
Return Values
Errors/Exceptions
Explainable Commands
Examples
See Also

Definition

MongoDB\Collection::explain

Explain the given command.

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

This method has the following parameters:

Parameter	Type	Description
`$explainable`	`MongoDB\Operation\Explainable`	The command to explain.
`$options`	array	Optional. An array specifying the desired options.

The $options parameter supports the following options:

Option Type Description

readPreference MongoDB\Driver\ReadPreference Optional. Read preference to use for the operation. Defaults to the collection’s read preference.

typeMap

array

Optional. 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 Optional. 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.

copy

<?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)
  }
}