DB2 ⭐ Featured
👁 0

Q: What is index-only access?

Answer:
Index-only access retrieves data from index without table access. All needed columns in index (including by include clause). Best performance. EXPLAIN shows INDEXONLY=Y. Design indexes for common queries.
index-only performance access
DB2 ⭐ Featured
👁 0

Q: Explain CREATE INDEX

Answer:
CREATE INDEX creates index on table. CREATE INDEX idx ON table(col1, col2). UNIQUE prevents duplicates. CLUSTER determines physical order. Include columns for index-only access. Drop unused indexes for insert performance.
index create ddl