PDF (US Ltr)
- 43.3Mb
PDF (A4)
- 43.4Mb
Man Pages (TGZ)
- 297.2Kb
Man Pages (Zip)
- 402.4Kb
Info (Gzip)
- 4.3Mb
Info (Zip)
- 4.3Mb
Search Results
https://dev.mysql.com/doc/refman/8.0/en/subquery-restrictions.html
FROM t ...); Exception: The preceding prohibition does not apply if for the modified table you are using a derived table and that derived table is materialized rather than merged into the outer query. (See Section 10.2.2.4, “Optimizing Derived ...
https://dev.mysql.com/doc/refman/8.0/en/order-by-optimization.html
Ideally, the value should be large enough for the entire result set to fit in the sort buffer (to avoid writes to disk and merge passes). To monitor the number of merge passes (to merge temporary files), check the Sort_merge_passes status variable.
https://dev.mysql.com/doc/refman/8.0/en/create-view.html
For more information, see Section 27.5.2, “View Processing Algorithms”, as well as Section 10.2.2.4, “Optimizing Derived Tables, View References, and Common Table Expressions with Merging or Materialization”. If the view does not exist, ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-recovery.html
During recovery, InnoDB reads corruption flags from both locations and merges results before marking in-memory table and index objects as corrupt. Change buffer merge Applying changes from the change buffer (part of the system tablespace) to leaf ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-innodb-indexes-table.html
If the amount of data in an index page falls below the MERGE_THRESHOLD value when a row is deleted or when a row is shortened by an update operation, InnoDB attempts to merge the index page with the neighboring index page. For more information, see ...For related usage information and examples, see Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object ...
https://dev.mysql.com/doc/refman/8.0/en/derived-condition-pushdown-optimization.html
When a derived table cannot be merged into the outer query (for example, if the derived table uses aggregation), pushing the outer WHERE condition down to the derived table should decrease the number of rows that need to be processed and thus speed ... MySQL 8.0.22 and later supports derived condition pushdown for eligible ...
https://dev.mysql.com/doc/refman/8.0/en/partitioning-management-range-list.html
A REORGANIZE PARTITION clause may also be used for merging adjacent partitions. You can reverse the effect of the previous statement on the members table as shown here: ALTER TABLE members REORGANIZE PARTITION s0,s1 INTO ( PARTITION p0 VALUES LESS ... Adding and dropping of range and list partitions are handled in a similar fashion, so we discuss the management of both sorts of partitioning in this ...
https://dev.mysql.com/doc/refman/8.0/en/sys-statements-with-sorting.html
sort_merge_passes The total number of sort merge passes by occurrences of the statement. avg_sort_merges The average number of sort merge passes per occurrence of the statement. The statements_with_sorting and x$statements_with_sorting views have ...
https://dev.mysql.com/doc/refman/8.0/en/multiple-column-indexes.html
If separate single-column indexes exist on col1 and col2, the optimizer attempts to use the Index Merge optimization (see Section 10.2.1.3, “Index Merge Optimization”), or attempts to find the most restrictive index by deciding which index ...
https://dev.mysql.com/doc/refman/8.0/en/window-function-optimization.html
Window functions affect the strategies the optimizer considers: Derived table merging for a subquery is disabled if the subquery has window functions. The optimizer makes no attempt to merge windows that could be evaluated in a single step (for ...