← Google Interview Insights

Google·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Quick Google data engineer screen, basically just one database fundamentals question. Nothing too wild but it's the kind of thing that trips you up if you haven't reviewed the basics recently.

Questions Asked (1)

Q1

What are the different types of indexes available in a relational database?

Technical Trade-offsData Modeling
Author's notes

Went through the usual suspects: B-tree, hash, composite, partial.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by categorizing indexes based on their structure (e.g., B-tree, hash) and their logical usage (e.g., primary, secondary, composite). Then, briefly explain each type's purpose and trade-offs, focusing on how they impact query performance and storage. Conclude by mentioning that the choice depends on the workload and data characteristics.

Pro tip: Demonstrate depth by discussing not just the types but also when to use each, and mention that over-indexing can degrade write performance. This shows you understand the practical trade-offs in database design.

1. Categorize by Structure

Begin by classifying indexes based on their underlying data structure, such as B-tree, hash, bitmap, and specialized types like GiST or GIN.

2. Categorize by Logical Usage

Explain indexes based on their role: primary key, unique, composite, covering, and full-text indexes.

3. Explain Each Type Briefly

For each type, provide a one-sentence description of its purpose and a key characteristic (e.g., B-tree for range queries, hash for equality).

4. Discuss Trade-offs

Highlight the trade-offs: faster reads vs. slower writes, increased storage, and maintenance overhead.

5. Conclude with Selection Criteria

Summarize that the choice depends on query patterns, data volume, and write frequency, showing a balanced understanding.

Key Points to Mention

  • B-tree indexes: default in most databases, support range queries and sorting.
  • Hash indexes: efficient for equality comparisons but not range queries.
  • Composite indexes: index on multiple columns, order matters for query optimization.
  • Covering indexes: include all columns needed for a query, avoiding table lookups.
  • Bitmap indexes: efficient for low-cardinality columns, common in data warehousing.
  • Full-text indexes: specialized for text search, using inverted indexes.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.