1Z0-873 · Question #80
Which of the following SQL constructs are not available with all storage engines, i.e. which are storage engine dependent?
The correct answer is A. BEGIN and ROLLBACK have an effect only for tables managed by transactional storage engines, B. Some index types are available only for particular storage engines. The OPTIMIZE TABLE statement cleans up a MyISAM table by defragmenting it. This involves reclaiming unused space resulting from deletes and updates, and coalescing records that have become split and stored non-contiguously. OPTIMIZE TABLE also sorts the index pages if they are…
Question
Which of the following SQL constructs are not available with all storage engines, i.e. which are storage engine dependent?
Options
- ABEGIN and ROLLBACK have an effect only for tables managed by transactional storage engines,
- BSome index types are available only for particular storage engines.
- CLOAD DATA INFILE only works for tables managed by disk based storage engines, such as
- DOPTIMIZE TABLE only works for tables managed by storage engines that perform table level
How the community answered
(38 responses)- A76% (29)
- C8% (3)
- D16% (6)
Explanation
The OPTIMIZE TABLE statement cleans up a MyISAM table by defragmenting it. This involves reclaiming unused space resulting from deletes and updates, and coalescing records that have become split and stored non-contiguously. OPTIMIZE TABLE also sorts the index pages if they are out of order and updates the index statistics. OPTIMIZE TABLE also works for InnoDB tables, but maps to ALTER TABLE, which rebuilds the table. This updates index statistics and frees space in the clustered index.
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