Describes a query that can be compared against an IndexKeyEntry in a way that allows expressing exclusiveness on a prefix of the key. More...

#include <index_entry_comparison.h>

Detailed Description

Describes a query that can be compared against an IndexKeyEntry in a way that allows expressing exclusiveness on a prefix of the key.

This is mostly used to express a location to seek to in an index that may not be representable as a valid key.

The "key" used for comparison is the concatenation of the first 'prefixLen' elements of 'keyPrefix' followed by the last 'keySuffix.size() - prefixLen' elements of 'keySuffix'.

The comparison is exclusive if either 'prefixExclusive' is true or if there are any false values in 'suffixInclusive' that are false at index >= 'prefixLen'.

Portions of the key following the first exclusive part may be ignored.

e.g.

Suppose that

keyPrefix = { "" : 1, "" : 2 }
prefixLen = 1
prefixExclusive = false
keySuffix = [ IGNORED, { "" : 5 } ]
suffixInclusive = [ IGNORED, false ]

==> key is { "" : 1, "" : 5 }
    with the comparison being done exclusively

Suppose that

keyPrefix = { "" : 1, "" : 2 }
prefixLen = 1
prefixExclusive = true
keySuffix = IGNORED
suffixInclusive = IGNORED

==> represented key is { "" : 1 }
    with the comparison being done exclusively

'prefixLen = 0' and 'prefixExclusive = true' are mutually incompatible.

See also: IndexEntryComparison::makeQueryObject

Public Attributes
BSONObj	keyPrefix

int	prefixLen = 0
	Use this many fields in 'keyPrefix'. More...

bool	prefixExclusive = false
	If true, compare exclusively on just the fields on keyPrefix and ignore the suffix. More...

std::vector< const BSONElement * >	keySuffix
	Elements starting at index 'prefixLen' are logically appended to the prefix. More...

std::vector< bool >	suffixInclusive
	If the ith element is false, ignore indexes > i in keySuffix and treat the concatenated key as exclusive. More...

Member Data Documentation

◆ keyPrefix

BSONObj mongo::IndexSeekPoint::keyPrefix

◆ keySuffix

std::vector<const BSONElement*> mongo::IndexSeekPoint::keySuffix

Elements starting at index 'prefixLen' are logically appended to the prefix.

The elements before index 'prefixLen' should be ignored.

◆ prefixExclusive

bool mongo::IndexSeekPoint::prefixExclusive = false

If true, compare exclusively on just the fields on keyPrefix and ignore the suffix.

◆ prefixLen

int mongo::IndexSeekPoint::prefixLen = 0

Use this many fields in 'keyPrefix'.

◆ suffixInclusive

std::vector<bool> mongo::IndexSeekPoint::suffixInclusive

If the ith element is false, ignore indexes > i in keySuffix and treat the concatenated key as exclusive.