This process can help improve performance by reorganizing how data is stored and accessed. 9. N. First, connect to your MySQL server as the root user: sudo mysql -u root -p. See Section 17. 2. After the DB upgrade to 5. 6 Other Optimization Tips. 7. The server maintains histogram statistics about column values in the column_statistics data dictionary table (see Section 10 10. This will analyze the table and make changes to improve performance. 4. 3 Optimizing INFORMATION_SCHEMA Queries. The table in question stores logs. Aug 12, 2017 · 1. Tuning these statements is a top priority, whether to achieve sub-second response times for dynamic web pages, or to chop hours off the time to generate huge overnight reports. Following is the syntax of the MySQL OPTIMIZE TABLE According to MySQL Certification Guide : The OPTIMIZE TABLE statement cleans up a MyISAM table by defragmenting it. After extensive changes to a table, this statement may also improve performance of statements that use the table, sometimes significantly. Only one table name is permitted for this syntax. 16 ORDER BY Optimization. I'm having issues with a database that is getting quite slow. In your role as a database designer, look for the most efficient way to organize your schemas, tables, and columns. Oct 5, 2010 · 10. ) If you deleted half of the rows, you should optmize your table. Nov 13, 2023 · Command: In MySQL’s InnoDB storage engine, the OPTIMIZE TABLE command can be used to reorganize a table and its associated indexes. OPTIMIZE TABLE works for InnoDB , MyISAM, and You can use OPTIMIZE. For best performance with MEMORY tables, examine the kinds of queries against each table, and specify the type to use for each associated index, either a B-tree index or a hash index. MyISAM tables are used as the exception rather than the preferred choice for storage engine. B. Aug 16, 2011 · Internally, OPTIMIZE TABLE perform several operations (copying data to a temp file, recreate indexes, recompute index statistics). But before doing so, I would (of course) like to know if there is anything that can happen to the data in the tables, or if this operation is entirely harmless. An exclusive table lock is only taken briefly during the prepare phase and the commit phase of the operation. 3 Optimizing for Many Tables. The third statement removes the histogram for c2 , leaving those for c1 and c3 unaffected. But in practice, it won't improve performance in a significant way. #4 and #5: Indexes and partitions. This chapter explains how to optimize MySQL performance and provides examples. These software constructs result in CPU and I/O operations at the hardware level, which you must minimize and make as efficient as possible. It's also useful to run this statement periodically with a table that contains several variable-character-width columns (i. In some cases, MySQL is able to do much better than that and The manual says about "optimize table": "Deleted rows are maintained in a linked list and subsequent INSERT operations reuse old row positions. To optimize several tables simultaneously, list them separated by commas: OPTIMIZETABLE table_name1, table_name2, table_name3; To avoid lengthy rebuild times for full-text indexes on large tables, you can use the innodb_ft_num_word_optimize option to perform the optimization in stages. Depending on your job role (developer, DBA, or a combination of both), you might optimize at the level of individual SQL statements, entire applications 10. 2 Optimizing SQL Statements. When the number of tables runs into the thousands or even millions, the overhead of dealing with all 10. アプリケーションがデータベースに対して多くの DELETE および UPDATE 操作を実行している場合、MySQL のデータファイルが断片化される可能性が高くなります。. On the CREATE INDEX statement, use the clause USING BTREE or USING HASH. mytable; Look at two scenarios involving innodb_file_per_table and this OPTIMIZE TABLE. 3. 17以下ではOPTIMIZE TABLEが更新ステートメントをブロックしてしまうため、 本番環境で使っているMySQLにOPTIMIZE TABLEを行う場合には時間的な余裕を持って行うか、 mysqldumpを使ってdumpしたSQLを使用して別テーブルとして用意したのちにRENAME TABLEをするなど Dec 11, 2023 · MySQL でテーブルを最適化するタイミングと理由. All of the following tables are used as constant tables: SELECT * FROM t WHERE primary_key=1; SELECT * FROM t1,t2 WHERE t1. Are there pros and cons I should take 10. As when tuning application code, you minimize I/O, keep related items together, and plan ahead so that performance stays high as the data volume increases. mytable; SUGGESTION. May 22, 2023 · CREATE TABLE new_table [AS] SELECT [columns] FROM old_table; MySQL will recreate all columns, data types and data from the old_table. Connect to your MySQL database, and execute the following query, which will display how much unused space are available in every table. Example Code: -- Syntax: Use your_database_name; mysql> USE test; Once connected with the desired database, use the following query to get the table’s status. ANALYZE TABLE with the DROP HISTOGRAM clause removes histogram statistics for the named table columns from the data dictionary. " Feb 23, 2013 · First of all, I am new to optimizing mysql. TABLEAS SELECT , INSERT. Use this statement to optimize the data contained in a table. TABLE is completed in place. 예제 코드: mysql>SELECTTABLE_NAME, data_length, data_free->FROM information_schema. 3. Database performance depends on several factors at the database level, such as tables, queries, and configuration settings. Queries, in the form of SELECT statements, perform all the lookup operations in the database. mytable; Note that mysql performs something the following under the 10. I have a table with 707 GB in my database, I tried the command "optimize table mytable" but unfortunatelly it seems not work because my table keep the size 707 GB. So, it's supposed to hit the index and run almost instantly, and it did when the testing started, but now, after millions of rows were removed, it gets stuck in the 'optimizing' state for several minutes. I know that optimize table is supposed to take quite a long time, but it has now been around 10 hours and I'm still waiting for it to finish. 11, “Previous NDB Cluster Issues Resolved in NDB Cluster 8. 最適化には、いくつかのレベルでの構成、チューニング、およびパフォーマンスの測定が含まれます。. Identify Tables for Optimization. Performance is not the reason to use OPTIMIZE TABLE. Note. Example: If you optimize mydb. 6 to 5. This statement requires SELECT and INSERT privileges for the table. . This process can be a lot faster, especially for large indexes which would get inserts in very random order Jun 4, 2015 · The message you are getting is basically MySQL server repeating what the InnoDB storage engine told MySQL server: Table does not support optimize is the InnoDB storage engine saying "I (the InnoDB storage engine) don't do an OPTIMIZE operation like my friend (the MyISAM storage engine) does. This statement is not supported for views. 6, “Limits on Table Size” . 33 , the entire optimization script can complete within 1. Analyze table performs a key distribution analysis and stores the distribution for the named table or tables. 5. The script 9. 예제 코드: mysql> OPTIMIZETABLE tableName1, tableName2; 이제 다음 명령을 사용하여 원하는 테이블이 최적화되었는지 확인합니다. # mysqlcheck -u username -p --auto-repair --check --optimize database_name. innodb. The most general way to satisfy a GROUP BY clause is to scan the whole table and create a new temporary table where all rows from each group are consecutive, and then use this temporary table to discover groups and apply aggregate functions (if any). 2GB and the optimize table script for this table has consume 45 mins . For more information, see the MySQL documentation for File-per-table tablespaces . If the optimization processes t1 first and the WHERE clause produces an empty result, the join must necessarily be empty and the derived table need not be materialized. The index entries act like pointers to the table rows, allowing the query to quickly determine which rows match a condition in the WHERE clause, and retrieve the other May 24, 2023 · Table optimization, in the context of MySQL, refers to the process of managing data storage effectively and enhancing the speed of data retrieval operations. primary_key=1 AND t2. This involves reclaiming unused space resulting from deletes and updates, and coalescing records that have become split and stored non-contiguously. Improving database performance in general. This seems to contradict itself. You can use this statement to verify that the contents are the same before and after a backup, rollback, or other operation that is intended to put the data back to a known state. The first step is to identify whether you have fragmentation on your MySQL database. 63 to 0. mytable, you enter this command: OPTIMIZE TABLE mydb. Apr 25, 2024 · This article explained different methods for improving MySQL performance and tuning your database. Since fulltext re-organization can take a long time May 12, 2010 · For InnoDB tables, OPTIMIZE TABLE is mapped to ALTER TABLE, which rebuilds the table to update index statistics and free unused space in the clustered index. This is intended to be a temporary setting, and should be reset to 0 once the fulltext index has been re-organized. Some techniques for keeping individual queries fast involve splitting data across many tables. 2 Optimizing Subqueries, Derived Tables, and View References. It reorganizes the storage data in a way that increases the Input Output efficiency and reduces the storage space. まぁ何のことはなく、SHOW TABLE STATUSで We would like to show you a description here but the site won’t allow us. Optmize doesn't take so much like delete. The optimizer_switch system variable enables control over optimizer behavior. Apr 28, 2015 · The explain command on this query shows: '1', 'SIMPLE', NULL, NULL, NULL, NULL, NULL, NULL, NULL, 'Select tables optimized away'. Apr 27, 2012 · Optimize Table Taking Forever. B-tree indexes are fast for queries that do greater-than or less-than comparisons through You can use OPTIMIZE. 0 8. Is there anyother way I could use in order to reduce the table size? Ps: Engine Is InnoDB. I'm running mysql 5. An alternative is to configure the server to use innodb_file_per_table, but this will require a backup, drop database and restore. In fact, the example I have can be performed manually as shown. We must be connected to our database using the following command. 5 hours. The core logic of a database application is performed TABLE to reclaim the unused space and to defragment the data file. Aug 27, 2013 · Optimizing this table is going to take a lot of time. However, ALTER TABLE ignores DATA. 10. 17 GROUP BY Optimization. 2 Disadvantages of Creating Many Tables in the Same Database. #2 and #3: Check up on MySQL storage engines and schema design. 本エントリの内容. The OPTIMIZE TABLE script have to run for 4 hour. The first – and most skipped! – performance upgrade every user of MySQL should do is tweak the configuration. Run the one of the above OPTIMIZE TABLE scenarios on one PXC node at a time while redirecting reads and writes from the cluster. In order to use it to update fulltext index statistics, the innodb_optimize_fulltext_only system variable must be set to 1. id; The best join combination for joining the tables is found by trying all possibilities. If you want to have a tool that repairs tables by default, you should just make a copy of mysqlcheck named mysqlrepair, or make a symbolic link to mysqlcheck named mysqlrepair. An ORDER BY with and without LIMIT may return rows in different orders, as discussed in Section Dec 29, 2022 · In this article, we’ll walk through five ways to quickly improve your MySQL database performance. Let’s get started! MySQL and your applications. e. 1 WHERE Clause Optimization. Next, check out our guide on how to optimize MySQL tables. SCENARIO #1 : innodb_file_per_table disabled. 1 Optimizing SELECT Statements. Changes to this variable affect execution of all subsequent queries; to affect one query differently from another, it is necessary to change optimizer_switch before each one. In the WHERE clause, you have to allow for the values from the table on the right to be NULL (or else you'll effectively change the LEFT JOIN into an INNER JOIN). The tuning guidelines in this section help to speed up all kinds of MySQL applications. the mysql query cache was turned off to demonstrate. 1 How MySQL Opens and Closes Tables. 6. You can optimize a table in the same way by using the OPTIMIZE TABLE SQL statement. alter. Feb 21, 2024 · You can execute this command through any MySQL client. 2. That's why I recommend ALTER TABLE dat ENGINE=InnoDB; ANALYZE TABLE dat;. MySQL provides optimizer control through system variables that affect how query plans are evaluated, switchable optimizations, optimizer and index hints, and the optimizer cost model. I have no experience with MySQL, but your issue may not be platform specific. 4” . 9. 2 Switchable Optimizations. Jun 30, 2022 · Fixing Slow Queries. この章では、MySQL のパフォーマンスを最適化する方法について説明し、例を示します。. MySQL 8. See Section 10. 5. Dec 9, 2010 · Why you shouldn’t necessarily optimize tables with MySQL OPTIMIZE. Replace username with your MySQL username and database_name with your database name. In my company we have tables about 2-3 gb. MySQL. MySQLのInnoDBの領域最適化について最近確認し直したことをまとめたいと思います. As a dry run I ran the same command (optimize table) on a smaller table in the same DB and mysql insists on a recreate+analyze instead. How to optimize InnoDB tables in MySQL. This tip is valid for inserts into any table, not just InnoDB tables. CHECKSUM TABLE reports a checksum for the contents of a table. The default behavior of checking tables ( --check) can be changed by renaming the binary. 4 MyISAM Table Optimization. I ran this query and it identified 148 tables for optimization. You can use OPTIMIZE TABLE to reclaim the unused space and to defragment the data file. The core logic of a database application is performed through SQL statements, whether issued directly through an interpreter or submitted behind the scenes through an API. 27, this is displayed in the output of OPTIMIZE TABLE when you run it on an InnoDB table, as shown here: Chapter 8 Optimization. If the data is huge, remove the PXC node from the cluster, run OPTIMIZE TABLE at will, and add the PXC back into Jun 12, 2019 · Step 5 — Testing Your MySQL Server with Query Cache Enabled. Its value is a set of flags, each of which has a value of on or off to indicate whether the corresponding optimizer behavior is enabled or disabled. Example Code: See full list on phoenixnap. Although it is not always reproducible, but possibly related: 여러 테이블을 최적화하려면 다음 쿼리를 사용하십시오. By default, an OPTIMIZE TABLE will defragment a table. #1: Managing the my. 5 Optimizing Database Privileges. OPTIMIZE TABLE works for InnoDB , MyISAM, and ARCHIVE tables. ibd file for the table is reduced after an optimize table. Apr 25, 2016 · This tutorial explains how to optimize MySQL to defrag tables and reclaim unused space. 52 to 4. I have just read somewhere that using above alter table statement will optimize an existing table. TABLE to reclaim the unused space and to defragment the data file. The table rebuild triggered by OPTIMIZE. If you want that your queries will be faster, optimize your table. Apr 5, 2011 · hugeCrossingTable: INDEX(field1, field3, field2) otherTable: INDEX(field2, field1, field3) and drop the current KEY field1 ( field1) as being redundant. Depending on the size of your innodb_buffer_pool (if the table is innodb), free memory on the host, I would try to preload the whole table in the page cache of the OS, so that at least reading the data will be sped up by a couple orders of The performance of OPTIMIZE on NDB Cluster tables can be tuned using --ndb-optimization-delay, which controls the length of time to wait between processing batches of rows by OPTIMIZE TABLE. この記事はMySQL Advent Calendar 2019の25日目の記事です。. MySQL OPTIMIZE TABLE Statement. 2, “Switchable Optimizations” ). This section explains how to optimize database operations for InnoDB tables. If you’re running Innodb Plugin on Percona Server with XtraDB you get the benefit of a great new feature – ability to build indexes by sort instead of via insertion. 4 current 5. Impact:Performance: Reorganizing is generally less resource Jun 6, 2023 · Conclusion – MySQL Optimize Table. If T2 loop is cancelled the optimize table (T3) will not fail in succeeding loops. optimization. InnoDB has been the default storage engine since 2010. We can use the OPTIMIZE TABLE command provided in MySQL to defragment the data used for storing the fragmented table content because of heavy INSERT, UPDATE, and DELETE operations on the table. 29 and it complained immediately, Table does not support optimize, doing recreate + analyze instead. To execute this statement, you need SELECT and INSERT privileges. Even if you use optimize table to free the space used from deleted records, it will reuse it later. Aug 9, 2022 · 1. This will leave the space previously occupied to add further to the Dec 24, 2019 · MySQL InnoDBの領域最適化. tables->WHERE table 10. The reorganized tables require less disk I/O to perform full table scans. The analyzer in phpMyAdmin recommends that I run OPTIMIZE TABLE on my tables. The guidelines cover SQL operations that read and Feb 14, 2020 · As per MySQL Documentation, OPTIMIZE TABLE and ANALYZE TABLE. 第 8 章 最適化. 3 Optimization and Indexes. When performing bulk inserts, it is faster to insert rows in Mar 29, 2011 · MySQL has an OPTIMIZE TABLE command which can be used to reclaim unused space in a MySQL install. I deleted just over half of them because disk space was starting to become an issue. One means of control over optimizer strategies is to set the optimizer_switch system variable (see Section 10. 4 Optimizing Data Change Statements. 7 (the current version) has much better defaults Oct 12, 2015 · OPTIMIZE NO_WRITE_TO_BINLOG TABLE mydb. Optimization involves configuring, tuning, and measuring performance, at several levels. Method #5: Repair During Server Startup. OPTIMIZE TABLE mydb. InnoDB is the storage engine that MySQL customers typically use in production databases where reliability and concurrency are important. In this step, you’ll run the same query you ran in Step 3 one more time to check how query cache has optimized the performance of your MySQL server. その結果、未使用のスペースが発生し Dec 13, 2017 · The filtering is being used to determine whether a specific row from the right (nullable) table should be matched up or not. 0 latest as well. 6 and I am trying to optimize a large table without mysql recreating it. For more information, see Section 25. mytable to be appended contiguously to ibdata1. 9, we are experiencing severe problems with the OPTIMIZE TABLE command which results in corrupted tables or the loss of all data in the affected table. 1. ALTER TABLE [tbl_name] TYPE=innodb. OPTIMIZE TABLE does a table repair and a key analysis, and also sorts Chapter 10 Optimization. For descriptions of all table options, see Section 13. ANALYZE TABLE works with InnoDB, NDB, and MyISAM tables. This has the effect of defragmenting the table and reducing the size of the table on disk down to 105MB. We can optimize multiple tables simultaneously by specifying their names in a comma-separated list within the same TABLE to reclaim the unused space and to defragment the data file. Feb 14, 2020 · Note that the dowhile() procedure is ongoing or can be ran for a short while then execute the insert on T2 even if it is continuously failing with Duplicate entry. column1 VARCHAR(5) NOT NULL, To optimize the table, issue the following command, where "mytablename" is the name of the MySQL table to optimise: After doing this (it may take a few seconds dpending on the size of the table, free space etc) and running "show table status" again, the result should look much better: Name: tblmailqueue. As you work on database performance, you start by Apr 24, 2017 · 16. OPTIMIZE TABLE works if the table is created in a separate tablespace, according to the Amazon RDS default innodb_file_per_table configuration setting. 5% @Michael-sqlbot As shown in my answer, I ran OPTIMIZE TABLE dat; in MySQL 5. The innodb_ft_num_word_optimize option defines the number of words that are optimized each time OPTIMIZE TABLE is run. By optimizing tables, one can make sure that the database server uses less disk space, processes queries more efficiently, and retrieves data faster. PostgreSQLでは「vacuum」とSQLクエリに投げるだけで全テーブル最適化してくれたのですが、OPTIMIZE TABLEの場合はひとつひとつテーブル名を指定しなければならないのでPHPで作りました。. The second statement updates the histograms for c1 and c3, leaving the c2 histogram unaffected. This variable has global and session values and can be changed at runtime. You can also define the columns and constraints and insert data to the new table like so: CREATE TABLE new_table (. cnf file. Jul 4, 2014 · 1. Engine: MyISAM. Feb 2, 2017 · If you have deleted most of the rows from a table, OPTIMIZE table needs only enough room to build a new, smaller, copy. The best way to improve the performance of SELECT operations is to create indexes on one or more of the columns that are tested in the query. To coalesce fragmented rows and eliminate wasted space that results from deleting or updating rows, run myisamchk in recovery mode: $> myisamchk -r tbl_name. For cases when a derived table requires materialization, the optimizer may add an index to the materialized table to speed up access to it. " So I'm guessing there will be some performance gain, even if the storage medium is SSD (as the linked list of Aug 9, 2022 · Description: Using OPTIMIZE TABLE on any InnoDB table returns a note that the table does not support optimize, yet it also returns a status of OK. 7 but still can be reproduced in 8. 1 Optimizing Storage Layout for InnoDB Tables. 9 Controlling the Query Optimizer. edited Aug 12, 2017 at 10:23. OPTIMIZE TABLE does a table repair and a key analysis, and also sorts ANALYZE TABLE t DROP HISTOGRAM ON c2; The first statement updates the histograms for columns c1, c2, and c3, replacing any existing histograms for those columns. The fact is that I have in my web application (around 400 queries per second), a query that uses a GROUP BY that i can´t avoid and that is the cause of creating temporary tables. Optimization is useful when many rows have been deleted from a table. This statement requires the SELECT privilege for the table. DIRECTORY and INDEX DIRECTORY when given as table options. OPTIMIZE TABLE uses online DDL for regular and partitioned InnoDB tables, which reduces downtime for concurrent DML operations. For example: OPTIMIZETABLE your_table_name; Simply replace your_table_name with the actual name of the table you want to optimize. It basically performs a query against the information_schema database for any table with data_free > 0 and builds a SQL statement to OPTIMIZE only those tables. Note that I'm using barracuda format and file-per-table. This article covers various methods, such as OPTIMIZE TABLE command, mysqlcheck tool, and GUI tool dbForge Studio for MySQL. Ever. 6, “AUTO_INCREMENT Handling in InnoDB” for details. 1. When we drill down further to each table , there are 1 table with 5. Check all MySQL tables at once. InnoDB is the default storage engine in MySQL. Look for bottlenecks (hardware and software), queries that are doing more work than needed, and consider using automated tools and the EXPLAIN function to evaluate your database. When doing bulk inserts into tables with auto-increment columns, set innodb_autoinc_lock_mode to 2 (interleaved) instead of 1 (consecutive). 6. 18, “CREATE TABLE Statement”. 8. If your MySQL database runs slowly, you can do a few things to speed it up — like optimizing your tables. Is it not possible to optimize without recreate in this 10. 本エントリでは下記の2点をランダム 10. 17, requires that you have the FILE privilege. Failures can happen more with 5. Dec 16, 2018 · OPTIMIZE TABELを全テーブルに実行. Both of those are "composite" and "covering". 3 Optimizer Hints. The effective maximum table size for MySQL databases is usually determined by operating system constraints on file sizes, not by MySQL internal limits. Jun 20, 2009 · Based on this article on Table Optimization. com Feb 1, 2010 · 10. After the copy is finished, it will rename, then drop the old table. MySQL dynamically optimize innodb tables without "file per table" setting. MySQL will create a copy of your table on disk. 33. Syntax. Feb 15, 2024 · First, we should analyze the tables that we want to optimize. – Oct 30, 2017 · Configuration Optimization. This section discusses optimizations that can be made for processing WHERE clauses. OPTIMIZE TABLE does a table repair and a key analysis, and also sorts Feb 1, 2010 · 10. 5 Optimizing for InnoDB Tables. The MySQL OPTIMIZE table helps you to optimize the table storage space. ALTER TABLE permits them only as partitioning options, and, as of MySQL 5. It had around 17 million records. MySQL will pick one of the tables to start with, then reach into the other one for the other columns needed. Is there a way (built-in command or common stored procedure) to run this optimization for every table in the database and/or server install, or is this something you'd have to script up yourself? 9. Using OPTIMIZE TABLE defragments InnoDB tables, which might reduce the size, especially right after major data changes like bulk deletes. 39 seconds. 業務の役割 (開発者、データベース管理者、また I’ve been researching how to optimize only fragmented tables in MySQL and reviewed this post on optimizing tables. But Sep 20, 2021 · Before we upgrade from version 5. The examples use SELECT statements, but the same optimizations apply for WHERE clauses in DELETE and UPDATE statements. Beginning with MySQL 5. The positive side is that the . If you invoke mysqlrepair, it repairs tables. Depending on your job role (developer, DBA, or a combination of both), you might optimize at the level of individual SQL statements, entire applications Oct 21, 2011 · To optimize the table will help to reduce the size (index will be recalculated etc. Oct 25, 2006 · Description: After upgrading our database server from MySQL 3. , VARCHAR , BLOB, and TEXT columns). 23. Last updated at 2019-12-26Posted at 2019-12-24. This section describes when MySQL can use an index to satisfy an ORDER BY clause, the filesort operation used when an index cannot be used, and execution plan information available from the optimizer about ORDER BY . Dec 20, 2016 · 5. Optimize table reorganizes the physical storage of table data and associated index data, to reduce storage space and improve I/O efficiency when accessing the table. My configuration was: max_heap_table_size = 16M tmp_table_size = 32M The result: temp table to disk percent + - 12. Running OPTIMIZE TABLE will cause all the data and index pages for mydb. Nov 2, 2023 · Learn how to identify and optimize fragmented MySQL tables to reclaim unused space and improve performance. Once your data reaches a stable size, or a growing table has increased by tens or some hundreds of megabytes, consider using the OPTIMIZE TABLE statement to reorganize the table and compact any wasted space. mytable; METHOD #3 OPTIMIZE LOCAL TABLE mydb. Another hint for deleting many many rows from Jun 3, 2024 · It’s a command-line utility that can check, repair, and optimize all database tables. 0 Reference Manual / / / / / WHERE Clause Optimization. primary_key=t1. I am not very sure that this would work and if yes, does it work even if table type is already InnoDB? mysql. 1 Optimization Overview. It also has a very positive affect on query performance, reducing the select query response time from 0. This statement generally works only with MyISAM, BDB 9. If the table had its own tablespace (built with innodb_file_per_table=ON), then the freed space will be returned to the OS. To optimize a table, you can use the OPTIMIZE TABLE command. 4 Optimizing Database Structure. bl al ry wh lk kh ye uy vl bu