What factors influence data access speed in SQL?

Main factors affecting data access speed in SQL:

• Indexes: Proper use and creation of indexes on columns frequently used for searching, sorting, and joins significantly speeds up data retrieval.
• Table structure: Normalization or denormalization, choosing the right data types, absence of redundant columns.
• Query optimization: Using EXPLAIN PLAN or similar tools to analyze and improve query execution plans. Avoid SELECT *, use JOIN instead of nested queries, minimize GROUP BY and ORDER BY on large datasets.
• Database server configuration: Caching settings (buffer pool), amount of RAM, number of CPU cores, disk subsystem configuration (SSD, RAID).
• Locks: Frequent or long locks caused by transactions can slow down access to locked data.
• Data volume: The larger the data in a table, the longer the search and processing may take without proper optimization.
• Partitioning schemes: Dividing large tables into smaller, manageable parts can speed up access to data in specific partitions.
• Data statistics: Up-to-date statistics allow the query optimizer to build efficient execution plans.