Quick study sessions to strengthen memory and retain key concepts.
Why move from in-memory collections to a relational database?
Because real application data must survive restarts and support relational queries. Orders, products, and users usually outlive one…
View Card →How can you tell if an index is used in a query?
By analyzing the execution plan with EXPLAIN. The execution plan details if and how indexes are used in…
View Card →How would you explain a sequential scan in SQL in an interview?
A full table scan without using indexes. Frame the concept in practical terms so you can explain it…
View Card →How can you balance the read and write performance in a database?
Strategically use indexes and batch writes. Balance is achieved by indexing selectively and optimizing write operations. For instance,…
View Card →What design consideration should be made for heavily searched columns?
Indexes should be created on heavily searched columns. Columns that are often used in WHERE clauses or joins…
View Card →How would you explain a common mistake when using indexes in an interview?
Indexing every column without need. Frame the concept in practical terms so you can explain it during interview…
View Card →When might it be counterproductive to use an index?
When the table is small or columns have low cardinality. Indexes on small tables or columns with few…
View Card →How can EXPLAIN be used to understand a query's execution plan?
EXPLAIN shows how SQL queries are executed. The EXPLAIN command provides insights into how a query uses indexes…
View Card →Why do indexes slow down write operations?
Indexes require additional maintenance during writes. When you insert or update data, the database must also update the…
View Card →What does an index in a database mainly do?
An index speeds up data retrieval. Frame the concept in practical terms so you can explain it during…
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