Since Indices Speed Query Processing, Why Might They Not Be Kept On S

1.	Since Indices Speed Query Processing, Why Might They Not Be Kept On Several Search Keys?
Answer» REASONS for not keeping several search indices include: Every index requires additional CPU time and disk I/O overhead during inserts and deletions. Indices on non-primary KEYS might have to be changed on updates, although an index on the primary key might not (this is because updates typically do not modify the primary key attributes). Each extra index requires additional storage space. For queries which involve CONDITIONS on several search keys, efficiency might not be bad even if only some of the keys have indices on them. Therefore database performance is improved less by adding indices when many indices already EXIST Reasons for not keeping several search indices include:

Since Indices Speed Query Processing, Why Might They Not Be Kept On Several Search Keys?

Answer»

REASONS for not keeping several search indices include:

Every index requires additional CPU time and disk I/O overhead during inserts and deletions.
Indices on non-primary KEYS might have to be changed on updates, although an index on the primary key might not (this is because updates typically do not modify the primary key attributes).
Each extra index requires additional storage space.
For queries which involve CONDITIONS on several search keys, efficiency might not be bad even if only some of the keys have indices on them. Therefore database performance is improved less by adding indices when many indices already EXIST

Reasons for not keeping several search indices include:

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Since Indices Speed Query Processing, Why Might They Not Be Kept On Several Search Keys?

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