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https://dev.mysql.com/doc/refman/8.0/en/index-btree-hash.html
Understanding the B-tree and hash data structures can help predict how different queries perform on different storage engines that use these data structures in their indexes, particularly for the MEMORY storage engine that lets you choose B-tree or ...The index also can be used for LIKE comparisons if the argument to LIKE is a constant string that does not start with a wildcard ...
https://dev.mysql.com/doc/refman/8.0/en/glossary.html
The hash index is always built based on an existing B-tree index on the table. MySQL can build a hash index on a prefix of any length of the key defined for the B-tree, depending on the pattern of searches against the index. A hash index can be ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-row-format.html
The pages that make up each table are arranged in a tree data structure called a B-tree index. The B-tree index that represents an entire table is known as the clustered index, which is organized according to the primary key columns. Variable-length ... The row format of a table determines how its rows are physically stored, which in turn can affect the performance of queries and DML ...
https://dev.mysql.com/doc/refman/8.0/en/sorted-index-builds.html
In the third and final phase, the sorted entries are inserted into the B-tree. Prior to the introduction of sorted index builds, index entries were inserted into the B-tree one record at a time using insert APIs. This method involved opening a ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-compression-internals.html
InnoDB Data Storage and Compression All user data in InnoDB tables is stored in pages comprising a B-tree index (the clustered index). Secondary indexes in InnoDB tables are also B-trees, containing pairs of values: the index key and a pointer to a ... This section describes some internal implementation details about compression for InnoDB ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-innodb-cmp-table.html
COMPRESS_OPS The number of times a B-tree page of size PAGE_SIZE has been compressed. COMPRESS_OPS_OK The number of times a B-tree page of size PAGE_SIZE has been successfully compressed. COMPRESS_TIME The total time in seconds used for attempts to ... The INNODB_CMP and INNODB_CMP_RESET tables provide status information on operations related to compressed InnoDB ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-physical-structure.html
With the exception of spatial indexes, InnoDB indexes are B-tree data structures. Index records are stored in the leaf pages of their B-tree or R-tree data structure. InnoDB performs a bulk load when creating or rebuilding B-tree indexes. The ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-parameters.html
Normal operations can continue while the hash table is emptied, and executing queries that were using the hash table access the index B-trees directly instead. innodb_fill_factor defines the percentage of space on each B-tree page that is filled ...
https://dev.mysql.com/doc/refman/8.0/en/memory-storage-engine.html
A common performance issue is using the default hash indexes in workloads where B-tree indexes are more efficient. The MEMORY storage engine (formerly known as HEAP) creates special-purpose tables with contents that are stored in memory. Because ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-file-space.html
One is for nonleaf nodes of the B-tree, the other is for the leaf nodes. When you delete data from a table, InnoDB contracts the corresponding B-tree indexes. A percentage of pages are reserved for future growth so that pages in the B-tree can be ...