Mysql optimize table how long. The higher is this value, the longer the query runs.

Jul 4, 2014 · 1. Apr 13, 2022 · OPTIMIZE TABLE is essentially useless, especially for ENGINE=InnoDB. In fact, if you've got the time (and you do), it never hurts to throw in. 28 seconds . mytable; METHOD #3 OPTIMIZE LOCAL TABLE mydb. OPTIMIZE TABLE mydb. b_id AS b_id (SELECT b. 3 Optimizing INFORMATION_SCHEMA Queries. 17 that InnoDB can perform an optimize table with Online DDL, which means that selects, and even inserts, deletes and updates can be performed on the table while the optimize is running, if that is your case. Optimized MySQL configurations can decrease server CPU utilization by up to 50%, resulting in lower operational costs. May 24, 2023 · Use: SELECT ID, name FROM employees; 1. 4 MyISAM Table Optimization. Running OPTIMIZE TABLE will cause all the data and index pages for mydb. These software constructs result in CPU and I/O operations at the hardware level, which you must minimize and make as efficient as possible. Indexes that are not changed do not get updated. SELECT ID, nameFROM employees; 6. At most it will Sep 29, 2016 · That 31% does not translate into anything more than a negligible slowdown. OPTIMIZE TABLE works for InnoDB , MyISAM, and ARCHIVE tables. 10. villages. It's a read-only action, it just reads a random 10. 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. Some techniques for keeping individual queries fast involve splitting data across many tables. The time required to delete individual rows in a MyISAM table is exactly proportional to the number of indexes. The time required for inserting a row is determined by the Dec 29, 2022 · In this article, we’ll walk through five ways to quickly improve your MySQL database performance. I'm trying to figure out how to optimize a very slow query in MySQL (I didn't design this): Comparing that to a full count: The explain statement doesn't help me here: explain SELECT COUNT(*) FROM change_event me WHERE change_event_id > '1212281603783391'\G. 27, this is displayed in the output of OPTIMIZE TABLE when you run it on an InnoDB table, as shown here: Feb 1, 2010 · 10. To optimize several tables simultaneously, list them separated by commas: OPTIMIZETABLE table_name1, table_name2, table_name3; I’ve been researching how to optimize only fragmented tables in MySQL and reviewed this post on optimizing tables. #4 and #5: Indexes and partitions. OPTIMISE TABLE will be faster as the data will not have to be converted to a textual format used by mysqldump and then digested by the mysql command line client. 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 . 26. The reorganized tables require less disk I/O to perform full table scans. If you OPTIMIZE InnoDB table it creates a new index structure for it and copies records from the old table to the new. Apr 25, 2024 · A query is a request to search the database for data that matches a provided value. If it was OFF when the table was created, the table is located in the file ibdata1, which grows but never shrinks. mytable; Look at two scenarios involving innodb_file_per_table and this OPTIMIZE TABLE. The syntax of table_factor is extended in comparison with the SQL Standard. This will pass the query to mySQL and dump the results to an output file. 5 Optimizing Data Change Statements. Chapter 10 Optimization. Nov 20, 2014 · I have this huge 32 GB SQL dump that I need to import into MySQL. MySQL’s OPTIMIZE TABLE Command. When the copy is done it then switches the tables. 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. If you are using InnoDB then you can do another trick, This will rebuild the table by copying all the rows to a new table space and replacing the current table once done. This particular case is a serious performance bottleneck the way you have it. The latter accepts only table_reference, not a list of them inside a pair of Running OPTIMIZE TABLE on a table with a full-text index rebuilds the full-text index, removing deleted Document IDs and consolidating multiple entries for the same word, where possible. Jun 2, 2010 · It's used for reclaiming space and recreating indexes. In that case, the view could also be defined with: CREATE VIEW vw_data_summary_4 AS SELECT a. Technique 2 is the surest and safest. The result of the aforementioned query will depict the status of the optimization for every optimized table. SCENARIO #1 : innodb_file_per_table disabled. But there are better ways to do the delete, so that is another case to simply avoid. If the table has deleted or split rows, repair the table. Then do the same thing the day after, if the 10. mytable; if the table was MyISAM is this: ALTER TABLE mydb. Jun 20, 2009 · OPTIMIZE TABLE does a table repair and a key analysis, and also sorts the index tree so that key lookups are faster. 7 I cancelled OPTIMIZE running on a See full list on phoenixnap. In any case, if you value the data, it's a good idea to switch the table to InnoDB. optimize table doc. 4. Premature optimization is the root of all evil. 16 ORDER BY Optimization. 9. Jan 31, 2017 · OPTIMIZE TABLE table1; Sometimes your tables just need a little love, if they've grown rapidly and you haven't optimized them in a while the indices may be a little crazy. 3 Optimizing for Many Tables. I did the usual: mysql -uroot dbname < dbname. The default behavior of checking tables ( --check) can be changed by renaming the binary. FROM sspk. One of the rare cases where OPTIMIZE can be useful is just after deleting lots of rows from a table. If innodb_file_per_table is turned on (it's turned on by default), then you can reclaim that space using OPTIMIZE TABLE. The syntax for MySQL OPTIMIZE TABLE is this: OPTIMIZE TABLE <table1>, [table2], [table3], [tableN] You can optimize one or more tables in one go. 6 to 5. Note that I'm using barracuda format and file-per-table. I deleted just over half of them because disk space was starting to become an issue. Technique 1 is the fastest way. An ORDER BY with and without LIMIT may return rows in different orders, as discussed in Section Nov 2, 2023 · The basic syntax to optimize a MySQL table is: mysqlcheck -o database_name table_name -u username -p. An update statement is optimized like a SELECT query with the additional overhead of a write. For information about option files used by MySQL programs, see Section 6. txt_field FROM b WHERE a. CREATE TABLE id_temp_table ( temp_id int); The classic relational way to design this would be creating a separate table for each attribute. Here, database_name is the name of the database, and table_name is the name of the table you want to optimize. Database performance depends on several factors at the database level, such as tables, queries, and configuration settings. When the number of tables runs into the thousands or even millions, the overhead of dealing with all mysql> ALTER TABLE employees. For example: OPTIMIZETABLE your_table_name; Simply replace your_table_name with the actual name of the table you want to optimize. 27 sec) Records: 0 Duplicates: 0 Warnings: 0; Check the progress of the ALTER TABLE operation by querying the Performance Schema events_stages_current table. I use 'optimize table ' to maintein a table very Monday and Friday, usaually it runs 1 hour normally , but sometime ,the 'optimize table' operation take serval hours or longer, today the 'optimize table ' runs for near 10 hours . The OPTIMIZE TABLE script have to run for 4 hour. Optimization involves configuring, tuning, and measuring performance, at several levels. In fact, the example I have can be performed manually as shown. If so, follow the advice here. Oct 21, 2022 · MySQL offers a way to defragment a table using a simple command, OPTIMIZE TABLE. 6 Optimizing Database Privileges. This statement requires the SELECT privilege for the table. Identify Tables for Optimization. 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. Tried different approaches like batch deletes (described above). Another hint for deleting many many rows 8. There would only be 365 records for each year. The -p flag prompts you for the password. mysql> OPTIMIZE TABLE EMPLOYEES; Secondly, we can optimize multiple tables together, as shown below: mysql> OPTIMIZE TABLE EMPLOYEES, SALESINFO, FINANCES; While running optimization on a table, MySQL does the following tasks: May 31, 2024 · Optimize MySQL Tables Statement: Optimizing Multiple MySQL Tables at once. If you want that your queries will be faster, optimize your table. mytable; SUGGESTION. A number of table and partition maintenance tasks can be carried out on partitioned tables using SQL statements intended for such purposes. 5. You can optimize a table in the same way by using the OPTIMIZE TABLE SQL statement. OPTIMIZE TABLE performs ANALYZE TABLE after doing some table compression. I ran this query and it identified 148 tables for optimization. mytable ENGINE=MyISAM; ANALYZE TABLE mydb. Technique 2 is better because, sometimes, users create folders for general purposes in /var/lib/mysql (datadir) which are not database related. txt_field AS a_txt_field SUM (a. com . I haven't had to import such a huge SQL dump before. 1 Optimization Overview. 11, “Previous NDB Cluster Issues Resolved in NDB Cluster 8. (Within reason) Compress TEXT fields in the client, then use BLOB. 4 Optimizing Performance Schema Queries. Another way to get fast updates is to delay updates Dec 16, 2018 · まぁ何のことはなく、show table statusでテーブル一覧を取得し、1つ1つoptimize tableを実行しているだけです。 SHOW TABLE STATUSでテーブルの状態が取得できるので、data_free（開放できるデータ量）が0よりある場合、としていますが、もうちょい大きい値を設定した Repair. 1) Using the MySQL OPTIMIZE TABLE statement for MyISAM tables. (As you found out. 1 How MySQL Opens and Closes Tables. Records in such tables are never deleting, only inserting and updating. id) AS b_txt_field a. I'm having issues with a database that is getting quite slow. When I'm trying to execute query that selects points that are spatially near to the query points, total execution time takes too long. A query that gets data for only one of the million users and needs 17 seconds is doing something wrong: reading from the (rated_user_id, rater_user_id) index and then reading from the table the (hundreds to thousands) values for the rating column, as rating is not in any index. Feb 21, 2024 · You can execute this command through any MySQL client. Should I optimize such tables? How to verify if I should optimize such Feb 16, 2016 · Long answer Since mysql 5. Ditto for user_post_likes. Replace username with your MySQL username. As you work on database performance, you start by Apr 11, 2013 · Thoughts on the issue, thrown in random order: The obvious index for this query is: (rated_user_id, rating). INDEX(a) is useless if you have INDEX(a,b) OPTIMIZE TABLE is likely to be a waste of time. Feb 27, 2010 · 4. If the data is huge, remove the PXC node from the cluster, run OPTIMIZE TABLE at will, and add the PXC back into 10. 3 Optimizing DELETE Statements. Feb 11, 2014 · 4. If you need to get down to more fine grained times, query the summary table for full days and the current table for just the record count for the start and end days. MySQL also allows you to optimize multiple tables in a single command as follows: mysql> OPTIMIZE TABLE EMPLOYEE, DEPARTMENT, BENEFITS. We must be connected to our database using the following command. Ideally, you make a single connection, send the data for many new rows at once, and delay all index updates and consistency checking until the very end. The higher is this value, the longer the query runs. Let’s get started! MySQL and your applications. So if you're inserting the same type of stuff at the same rate over time - no need to run analyze often - do it maybe once a month. mytable, you enter this command: OPTIMIZE TABLE mydb. Oct 22, 2014 · What I personally like to do is put the above query in a text file and run this from the command line: cat theQuery. But it is not necessarily "bad"; INSERTs into table will fill in that free space. ANALYZE TABLE is much less impact for InnoDB. 2GB and the optimize table script for this table has consume 45 mins . 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. By default, the MySQL client installation includes the mysqlcheck. To optimize the table will help to reduce the size (index will be recalculated etc. In my company we have tables about 2-3 gb. Swap the current table with the new table in an atomic operation with a one time lock, which will be done in perceivably Apr 25, 2016 · This tutorial explains how to optimize MySQL to defrag tables and reclaim unused space. These tables, I believe, have never been optimized since creation. 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. The speed of the write depends on the amount of data being updated and the number of indexes that are updated. As you work on database performance, you start by Aug 24, 2022 · Ending the SQL statement with “\G” instead of “;” causes MySQL to return the query result in vertical format, which makes it easier to read tables with many long columns. Mar 20, 2024 · Here are the benefits of MySQL performance tuning: Cost Optimization: Identifying the performance-driving factor allows you to avoid over-provisioning and reduce costs by right-sizing servers. 484 sec / 27. There is a bug wherein it will do the whole table in spite of what you say. And the query is quite simple, which returns only ~17000 rows. The query cannot go right to OFFSET because, first, the records can be of different length, and, second, there can be gaps from deleted The mysqlcheck is a command-line utility provided by MySQL to check, repair, analyze, and optimize tables in MySQL server. #2 and #3: Check up on MySQL storage engines and schema design. OPTIMIZE TABLE works for InnoDB, MyISAM, and ARCHIVE tables. May 25, 2021 · I have MySQL (actually - MariaDB) database with some InnoDB tables. . 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. 0” . While InnoDB tables are automatically optimized, MyISAM and other types may require manual optimization. Example Code: Innodb is ACID compliant, the optimize table simply copies all records into a new table . ) 57. Oct 12, 2015 · OPTIMIZE NO_WRITE_TO_BINLOG TABLE mydb. Queries, in the form of SELECT statements, perform all the lookup operations in the database. Another way to get fast updates is to delay updates 10. 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. Let’s take some examples of using the MySQL OPTIMIZE TABLE statement. 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 Feb 15, 2024 · First, we should analyze the tables that we want to optimize. You can use OPTIMIZE. Dec 13, 2017 · bookmarks looks like a many:many mapping table. Then you can query that table for the total records. 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. After the DB upgrade to 5. Oct 11, 2009 · Create another table summarizing the record count for each day. After extensive changes to a table, this statement may also improve performance of statements that use the table, sometimes significantly. #1: Managing the my. MySQL OPTIMIZE TABLE statement examples. If your tables are just a few gigs, it shouldn't be too long (probably a few minutes). Beginning with MySQL 5. Dec 29, 2015 · 5. It is safe, but it may take long time to rollback. 2, “Using Option Files”. 5 hours. More precisely Duration / Fetch = 0. As you work on database performance, you start by Aug 16, 2011 · Internally, OPTIMIZE TABLE perform several operations (copying data to a temp file, recreate indexes, recompute index statistics). Run an ANALYZE on the new table. Basically, plan for a some downtime. When we drill down further to each table , there are 1 table with 5. sql It is taking too long. 2 Disadvantages of Creating Many Tables in the Same Database. I recommend you abandon the process rather than trying to speed it up. Connect to your MySQL database, and execute the following query, which will display how much unused space are available in every table. 441 sec. For MyISAM tables, the OPTIMIZE TABLE statement works as follows: Basically this table contains points of interest of an image with respective descriptors. mysqlcheck supports the following options, which can be specified on the command line or in the [mysqlcheck] and [client] groups of an option file. If you invoke mysqlrepair, it repairs tables. This statement requires SELECT and INSERT privileges for the table. The Query I am using is : SELECT cDistName , cTlkName, cGpName, cVlgName , cMmbName , dSrvyOn. There are a couple of methods to access the Table Maintenance tool from within dbForge Studio for MySQL. It's normal that higher offsets slow the query down, since the query needs to count off the first OFFSET + LIMIT records (and take only LIMIT of them). 1, “Configuring the Server” . 2 Optimizing SQL Statements. To get all the records it is taking 76. 7. To delete rows more quickly, you can increase the size of the key cache by increasing the key_buffer_size system variable. mytable in datadir /var/lib/mysql, you have the following files: /var/lib/mysql/mydb Mar 3, 2021 · If the table is ENGINE=InnoDB, then: Study the innodb_file_per_table Variable. For the MyISAM table mydb. 6. amount If your table is PARTITIONed (and you must OPTIMIZE), do it one partition at a time, and do not use OPTIMIZE. 2. So, you clearly have enough disk space. Run the one of the above OPTIMIZE TABLE scenarios on one PXC node at a time while redirecting reads and writes from the cluster. table: me. 1. Improving database performance in general. Is it not possible to optimize without recreate in this May 25, 2017 · I had a use case of deleting 1M+ rows in the 25M+ rows Table in the MySQL. To optimize insert speed, combine many small operations into a single large operation. Apr 24, 2017 · 16. Long answer: (It would help if you had provided SHOW CREATE TABLE. Please help to check the problem. While Amazon RDS accepts the OPTIMIZE TABLE command CHECKSUM TABLE reports a checksum for the contents of a table. Tables consume some space that isn't actively in use, but Amazon RDS allocates that space to the tables anyway. Table maintenance of partitioned tables can be accomplished using the statements CHECK TABLE , OPTIMIZE TABLE , ANALYZE TABLE, and REPAIR TABLE, which are supported for Running OPTIMIZE TABLE on a table with a full-text index rebuilds the full-text index, removing deleted Document IDs and consolidating multiple entries for the same word, where possible. employees ADD COLUMN middle_name varchar(14) AFTER first_name; Query OK, 0 rows affected (9. The first step is to identify whether you have fragmentation on your MySQL database. Yes, it is a chunk of disk space, but optimize needs 100% to do its task because it copies the table over. If the index pages are not sorted, sort them, If the table's statistics are not up to date (and the repair could not be accomplished by sorting the index), update them. TABLEAS SELECT , INSERT. Optmize doesn't take so much like delete. OPTIMIZE TABLE does a table repair and a key analysis, and also sorts Mar 9, 2019 · Doing optimize table on an InnoDB table is usually not necessary to do frequently, but only after you do a lot of insert/update/delete against the table in a way that could result in fragmentation. 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. I've found out that the fastest way (copy of required records to new table): Create Temporary Table that holds just ids. The following discussion refers to the join syntax described in Section 15. which is not acceptable . Oct 21, 2011 · 5. sql | mysql -u yourusername [+ command line args with db host, etc] -p > outputSQLCommands. The table in question stores logs. The amount of space needed by the optimization depends on the number of rows marked Apr 25, 2017 · But (as the long answer explains) that savings may be an over- or under-estimate in the case of NULLing. Jul 30, 2015 · 235. 6 and I am trying to optimize a large table without mysql recreating it. The above example tells us that the server only needs to scan 599 rows to get the result. However, I did have a backup available in case of problems. If you kill OPTIMIZE in the middle of this InnoDB will have to rollback. Various SQL performance tuning techniques help detect and optimize queries for better run times. My SQL Query with all the filters applied is returning 10 lakhs (one million) records . The only cure is several rather drastic steps. I'm running mysql 5. Sep 10, 2013 · If you had a foreign key in a (b_id) that references b (id) you could also try changing the JOIN to LEFT JOIN and compare performance. 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. mytable to be appended contiguously to ibdata1. id: 1. The Table Maintenance tool will be displayed as shown in the following screenshot. To optimize a full-text index, enable innodb_optimize_fulltext_only and run OPTIMIZE TABLE . 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. Apr 27, 2012 · Optimize Table Taking Forever. Depending on your job role (developer, DBA, or a combination of both), you might optimize at the level of individual SQL statements, entire applications Feb 11, 2019 · Copy the table data into the new table. 2, “JOIN Clause” . sql. 2 Optimizing UPDATE Statements. 33 , the entire optimization script can complete within 1. Just because this quote can never be told to often. REORGANIZE PARTITION can do a single partition. The ON clause should say only how the tables are related, it should not be used for Sep 20, 2021 · Before we upgrade from version 5. 3 Optimization and Indexes. I'd say run that rarely if at all. Depending on your job role (developer, DBA, or a combination of both), you might optimize at the level of individual SQL statements, entire applications 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. Nov 21, 2012 · 1. ) If you deleted half of the rows, you should optmize your table. This statement is not supported for views. In the Database menu select Table Maintenance option from the drop-down list as shown in the following screenshot. schemata table. 4 Maintenance of Partitions. analyze should be redone whenever the overall distribution of the indexed data changes significantly. The syntax for expressing joins permits nested joins. Behind the scenes, it uses the CHECK TABLE, REPAIR TABLE, ANALYZE TABLE, and OPTIMIZE TABLE statements. In general, you can have these separate tables: location, gender, bornyear, eyecolor. Are there pros and cons I should take Nov 21, 2023 · The OPTIMIZE TABLE statement works with InnoDB, MyISAM, and ARCHIVE tables. b_id = b. 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. I've stopped the optimize process a number of times in the past, without adverse effects. In MySQL, VARCHAR(512) will take a little bit of space even if empty or NULL. But you need at 8. To coalesce fragmented rows and eliminate wasted space that results from deleting or updating rows, run myisamchk in recovery mode: $> myisamchk -r tbl_name. 13. In mysql 5. Method 1. 5 million in around 3 hours. Assuming no locking issues, next thing to look at is the actual size of the table. 1. select_type: SIMPLE. There is a table with around 300 million rows, it's gotten to 1. Note that non-tiny InnoDB tables normally always say 4MB-7MB of "Data_free" in SHOW TABLE STATUS. See Section 5. May 1, 2022 · If the table type is MyISAM, writes lock out reads, so one long query on a MyISAM table can lock out all other connections and make your webserver run out of processes, for example. MySQL offers the OPTIMIZE TABLE command to reclaim unused space and to defragment the data file. And, whether a person can have only one value of an attribute. We can defragment the table in our previous example as follows: OPTIMIZE TABLE frag_table; Code language: SQL (Structured Query Language) (sql) If you use a storage engine that doesn’t support the OPTIMIZE TABLE command, you can use a null ALTER TABLE operation: Jun 18, 2023 · How to Use MySQL OPTIMIZE TABLE. Dec 2, 2010 · All you have to do to get space back from a table is: OPTIMIZE TABLE my_big_table; Note that this can take a while, it's not a near instant operation. The equivalent of OPTIMIZE TABLE mydb. 1 Optimizing Storage Layout for InnoDB Tables. 1 Optimizing SELECT Statements. This chapter explains how to optimize MySQL performance and provides examples. This will leave the space previously occupied to add further to the Feb 27, 2024 · We can use the above in one of the following ways: First, we optimize one table using this MySQL statement. Queries on large datasets are usually slow and occupy database tables, making the tables unavailable for other tasks. 33. Some query operators take a long time to run. Example: If you optimize mydb. For more information, see Section 25. 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. The following depends on whether certain attributes are always defined for a person, or not. This doesn't require building a copy of the table. With that you can schedule an optimize on the table knowing that your system continues to run. cnf file. It had around 17 million records. mytable; Note that mysql performs something the following under the Feb 1, 2010 · 10. 3. The analyzer in phpMyAdmin recommends that I run OPTIMIZE TABLE on my tables. 1 Optimizing INSERT Statements. " Aug 3, 2015 · Normalize repeated values. TABLE to reclaim the unused space and to defragment the data file. mytable; MyISAM. Do not PARTITION unless there is a valid reason for it; it is likely to make the footprint bigger, perhaps significantly bigger. 8 Nested Join Optimization. The information_schema would register the folder as a database in the information_schema. Number of records are already relatively big - around few millions. Engine: MyISAM. REPAIR TABLE table1; 10. 2 Optimizing Subqueries, Derived Tables, View References, and Common Table Expressions. To stop the process, I used KILL process_id where process_id is taken from the results of SHOW PROCESSLIST. In the case of DROPping, it is likely to be an underestimate of the shrinkage. If have MySQL installed, you should already have the 8. How can I optimize my SQL Query which should take less time. What you should do is measure before, do an optimization and then measure after. See Section 7. lx ti iv vl jj tf wh ej ty dm