1Z0-873 · Question #120
Which of the following are true for how BTREE and HASH index types should be used for MEMORY tables?
The correct answer is A. HASH index types are only for use with equality comparisions such as those using the = and <=> B. BTREE index types are preferable for use with comparisons that do not just use equality. The MEMORY storage engine supports two indexing algorithms, HASH and BTREE: MEMORY tables use hash indexes by default. This index algorithm provides very fast lookups for all operations that use a unique index. However, hash indexes are usable only for comparisons that use the…
Question
Which of the following are true for how BTREE and HASH index types should be used for MEMORY tables?
Options
- AHASH index types are only for use with equality comparisions such as those using the = and <=>
- BBTREE index types are preferable for use with comparisons that do not just use equality
- CBTREE index types are only for use with equality comparisons such as those using the = and <=>
- DHASH index types are preferable for use with comparisons that do not just use equality operators
How the community answered
(37 responses)- A73% (27)
- C16% (6)
- D11% (4)
Explanation
The MEMORY storage engine supports two indexing algorithms, HASH and BTREE: MEMORY tables use hash indexes by default. This index algorithm provides very fast lookups for all operations that use a unique index. However, hash indexes are usable only for comparisons that use the = or <=> operator. The BTREE index algorithm is preferable if the indexed column will be used with comparison operators other than = or <=>. For example, BTREE can be used for range searches such as id < 100 or id BETWEEN 200 AND 300.
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