Exam 1z0-908 topic 1 question 5 discussion

A. Updating index statistics is an I/O expensive operation. When InnoDB updates index statistics, it requires scanning the data pages on disk to calculate the statistics, which can be I/O-intensive, particularly if the table is large. The more pages InnoDB has to scan, the more expensive the operation becomes.

A. Correct D. it has to be innodb_stats_transient_sample_pages for this to be correct

D https://dev.mysql.com/doc/refman/8.0/en/innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages The number of index pages to sample when estimating cardinality and other statistics for an indexed column, such as those calculated by ANALYZE TABLE. [Increasing the value improves the accuracy of index statistics, which can improve the query execution plan], at the expense of increased I/O during the execution of ANALYZE TABLE for an InnoDB table. Not C https://dev.mysql.com/doc/refman/8.0/en/innodb-parameters.html#sysvar_innodb_stats_auto_recalc This setting applies to tables created when the innodb_stats_persistent option is enabled.

A. C is not correct because it mentions: "The innodb_stats_auto_recalc variable, which is enabled by default, controls whether statistics are calculated automatically when a table undergoes changes to more than 10% of its rows, not when new indexes are created.

C is Correct https://dev.mysql.com/doc/refman/8.0/en/innodb-performance-optimizer-statistics.html

C is correct

D is correct according to me.

D is not about persistent indexed. E might be the answer but not sure