Mysql optimizer script1/3/2024 Tuning techniques for queries also apply to constructs such as Hours off the time to generate huge overnight reports. Sub-second response times for dynamic web pages, or to chop Tuning these statements is a top priority, whether to achieve Statements, perform all the lookup operations in the database. We are very excited about this feature, This makes several of our customer applications more optimal.8.2.1.1 WHERE Clause Optimization 8.2.1.2 Range Optimization 8.2.1.3 Index Merge Optimization 8.2.1.4 Engine Condition Pushdown Optimization 8.2.1.5 Index Condition Pushdown Optimization 8.2.1.6 Nested-Loop Join Algorithms 8.2.1.7 Nested Join Optimization 8.2.1.8 Outer Join Optimization 8.2.1.9 Outer Join Simplification 8.2.1.10 Multi-Range Read Optimization 8.2.1.11 Block Nested-Loop and Batched Key Access Joins 8.2.1.12 IS NULL Optimization 8.2.1.13 ORDER BY Optimization 8.2.1.14 GROUP BY Optimization 8.2.1.15 DISTINCT Optimization 8.2.1.16 LIMIT Query Optimization 8.2.1.17 Function Call Optimization 8.2.1.18 Row Constructor Expression Optimization 8.2.1.19 Avoiding Full Table Scans MySQL 8.0 invisible index is an very interesting feature, This enables Database Architects / DBAs / Database Engineers to choose optimal indexing for MySQL performance and scalability. Mysql> alter table tab3 alter index uidx invisible ĮRROR 3522 (HY000): A primary key index cannot be invisible We cannot alter Primary Key to invisible index: mysql> create table tab3 | 1 | SIMPLE | tab1 | NULL | ref | idx_1 | idx_1 | 10 | const,const | 1 | 100.00 | Using index | ![]() Mysql> explain select * from tab1 force index (idx_1) where col1=20 and col2=30 ![]() We are converting the index “idx_1” visible to make optimizer forcibly use mysql> alter table tab1 alter index idx_1 visible | 1 | SIMPLE | tab1 | NULL | ref | i_idx | i_idx | 5 | const | 1 | 33.33 | Using where | | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | Let’s try, How we can forcibly make optimizer use the index i_idx (this works because index is not invisible) mysql> explain select * from tab1 force index (i_idx) where col1=20 and col2=30 Now, Let see we can forcefully make optimizer use the invisible index (here it is – idx_1) mysql> explain select * from tab1 force index (idx_1) where col1=20 and col2=30 ĮRROR 1176 (42000): Key 'idx_1' doesn't exist in table 'tab1' Using invisible index mysql> show create table tab1 \G Step 2 is with “alter table script” mysql> alter table tab1 alter index idx_1 invisible There are two ways you can create invisible indexes: How can you create MySQL invisible indexes? Testing which index is efficient for many queries, You can test them by enabling invisible index and do not forget to disable them before testing with another invisible index, You can test index efficiency in production system (instant gratification indeed !).Even when optimizer force index, invisible indexes will not be invoked. On-demand indexing, You will have index (up-to-date with data) but you can make it visible or invisible.You want to make only one query to use that index, In this case “invisible index” is a great option. ![]() Why we really love invisible indexes in MySQL 8.0? That means, Index will still be maintained and keep up-to-date as data is modified, but no queries will be permitted to make use of the index (even if the query uses a FORCE INDEX hint). Invisible indexes are a new feature in MySQL 8.0, which mark an index unavailable for use by the optimizer. Now please don’t get confused with “ disabled indexes“, “invisible indexes are not disabled indexes, MYISAM supports disabled indexes, ” , The disabled indexes halt maintenance of an index. MySQL 8 supports invisible indexes, This allows you to on-demand enable/disable indexes from being used by MySQL optimizer.
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