How are indexes used in MongoDB data structure?
Indexes are special data structures [ 1] that store a small portion of the collection’s data set in an easy to traverse form. The index stores the value of a specific field or set of fields, ordered by the value of the field. The ordering of the index entries supports efficient equality matches and range-based query operations.
Which is the best geospatial index for MongoDB?
To support efficient queries of geospatial coordinate data, MongoDB provides two special indexes: 2d indexes that uses planar geometry when returning results and 2dsphere indexes that use spherical geometry to return results. See 2d Index Internals for a high level introduction to geospatial indexes.
When to use regex or case insensitive Index in MongoDB?
If the sole reason for using a regex is case insensitivity, use a case insensitive index instead, as those are faster. If you are self-managing MongoDB, you can optionally place indexes on their own separate volume, allowing for faster disk paging and lower contention.
Is the _ ID field always returned in MongoDB?
A common gotcha when trying to achieve covered queries is that the _id field is always returned by default. You need to explicitly exclude it from query results, or add it to the index. In sharded clusters, MongoDB internally needs to access the fields of the shard key.
How does the secondary index work in InnoDB?
In InnoDB, each record in a secondary index contains the primary key columns for the row, as well as the columns specified for the secondary index. InnoDB uses this primary key value to search for the row in the clustered index.
How are ObjectIDs represented in Mongoose by default?
Many other databases use a numeric id property by default, but in MongoDB and Mongoose, ids are objects by default. MongoDB ObjectIds are typically represented using a 24 hexadecimal character string, like ‘5d6ede6a0ba62570afcedd3a’. Mongoose casts 24 char strings to ObjectIds for you based on your schema paths.