Optimize SQL for High Throughput | Dataford Interview Questions

Explain how you would optimize a SQL query for a high-transactional database.

Assume the query must summarize settled transactions for active accounts during January 2026. Discuss query structure, indexing, execution-plan analysis, and trade-offs relevant to a write-heavy PostgreSQL database.

Output

One row per qualifying active account, with account_id, account_name, transaction_count, and total_amount
Include only January settled transactions whose total amount is positive
Order by total_amount descending, then account_id ascending

Schema

accounts

Column	Type	Description
account_idPK	INT	Unique account identifier
account_name	VARCHAR(100)	Display name of the account
is_active	BOOLEAN	Whether the account is currently active

transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
account_id	INT	Account associated with the transaction
status	VARCHAR(20)	Transaction processing status
created_at	TIMESTAMP	Transaction creation timestamp
amount	NUMERIC(12,2)	Signed transaction amount

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