Duplicate
A record that describes the same real thing as another record in the same dataset. An exact duplicate matches in every field; a near duplicate differs in spelling, format, or detail.
Two identical rows are not always duplicates. Two purchases of the same item by the same customer on the same day can be two real events, and only a key can tell them apart.
Where it comes up
- Exact duplicate rowsThe same row appears more than once, identical in every column.
- Near-duplicate recordsTwo rows describe the same real thing but differ enough that an exact comparison misses them.
- Duplicate keys with conflicting valuesTwo rows share an identifier that should be unique, but disagree on other fields.
See also
- DeduplicationFinding records that describe the same real thing and reducing them to one.
- UniquenessWhether each real thing appears only once in a dataset: one row per customer, and no order number used twice.
- MergeCombining two or more records judged to describe the same thing into a single record. The word is also used for joining two tables, and for merged cells in a spreadsheet; in data cleaning the first meaning is the usual one.