medium10 pts · first answer countsindexingperformancepostgresql

Benefit of INCLUDE in an index

A hot query is SELECT status FROM orders WHERE customer_id = $1. You change the index to CREATE INDEX ON orders (customer_id) INCLUDE (status). What does that gain?

A.It makes status unique for each customerB.It sorts each customer's rows by status, so queries that filter on status no longer need a separate indexC.It compresses the orders table on diskD.The query can be answered from the index alone (an index-only scan) without visiting the table rows

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