Middle
What data should not be indexed?
sobes.tech AI
Answer from AI
The following data types should not be indexed:
- Large binary data (BLOBs/TEXTs): Indexing such fields requires large amounts of memory and disk space, and searching for partial text matches in the index is inefficient.
- Fields with low cardinality: Fields containing very few unique values (e.g., boolean fields, status fields with multiple values) do not provide significant search benefits, as the index will contain many duplicate values.
- Frequently changing fields: Indexing such fields leads to constant index updates, which can negatively impact write performance.
- Fields rarely queried: Creating and maintaining an index for such fields is impractical, as the cost of maintenance outweighs the benefit of speeding up infrequent queries.
- Fields with many NULL values: In most databases, NULL values are either not included in the index or are handled inefficiently.
- Derived or computed fields: For such fields, it is usually better to index the source fields and use predicates (e.g., WHERE conditions) for filtering.
When deciding on indexing, it is important to consider the trade-off between read acceleration and write slowdown, as well as resource consumption. Regular analysis of query execution plans helps determine whether the existing index is effective or needs adjustment.