should i use mysql query cache MySQL query cache can improve certain apps performance where reading data prevails over adding or updating it. The configuration variable that governs the size of the query cache is query_cache_size. It should be noted that certain MySQL forks like Drizzle have decided to totally delete the query cache from their code due to problems it created. The following two queries will be cached differently in the MySQL cache because The MySQL documentation states You can defragment the query cache to better utilize its memory with the FLUSH QUERY CACHE statement. 1 Distrib 10. Why Every Business Should Use MySQL Enterprise Edition 2020 02 20 Staying off the Front Page with MySQL Enterprise Edition 2019 08 22 MySQL InnoDB Cluster New features in 8. Aug 15 2014 MySQL query cache is a functionality implemented in MySQL database servers that enables caching of query results. Documentation Changes Required. I will start with the basic memcached installation on Ubuntu 14. So let s turn it on. Enabling MySQL Query Cache with Zend Framework through PDO MYSQL_ATTR_USE_BUFFERED_QUERY Posted on November 9 2008 3 comments It s interesting that if you read through the Zend dB manual they mention a big problem with Zend Framework namely that since Zend uses prepared statements if you re running a pre 5. 10 You can use the same SQL SELECT command into a PHP function mysql_query . mysql gt FLUSH QUERY CACHE does NOT clear out the query cache but rather defrags the cache and leaving the cached query results in place. The FLUSH TABLES statement also does this. Mar 12 2009 MySQL 39 s query cache is an impressive piece of engineering if sometimes misunderstood. The query_cache_type variable should be set to ON and the nbsp 15 Nov 2016 The query cache stores the text of a Select statement together with the But cacheable queries take out an exclusive lock on MySQL 39 s query cache. 1ms and it can use query cache as well. The fact that it is transparent to the app no need to rewrite queries and db never serves stale data is its main advantage over other solutions. com Oct 29 2017 LIMIT 1 was around 0. Introduction to Query Cache. Use stack_trace in MySQL which will help you to differentiate between bugs track and fix them. 0 of MySQL. Aurora s query cache doesn t suffer from scalability issues as the query cache does in MySQL . But whenever possible you should check the version of MySQL in use and upgrade to the latest. However if not implemented correctly it can do more harm than good The query cache offers the potential for substantial performance improvement but do not assume that it will do so under all circumstances. Nov 05 2014 mysql gt RESET QUERY CACHE will clear out the query cache. If you use custom SQL directly it is not. When using SQL_NO_CACHE in a query the server does not use the query cache. 20 and is removed in MySQL 8. This site uses cookies to help personalise content tailor your experience and to keep you logged in if you register. In this setup I 39 m going to use MySQL database server. It compares incoming queries that start with SEL to a hash table and if there is a match returns the results from the previous execution of the query. Without query cache. Aurora s brand new query cache makes the feature worth revisiting. On the face of it this may seem a sensible approach but over time issues with the implementation have become apparent hence the planned deprecation. pl Enter the root password and mysql root password if it ask for the passwords. So the query cache isn t checked. memcache and sql query cache are independent of each other and both can be used without impacting each other. query Tfields e ip. This function is used to execute the SQL command and then later another PHP function mysql_fetch_array can be used to fetch all the selected data. On one end the CPU maintains several levels of cache to speed up its computations and on the other web apps make aggressive use of caching solutions like Redis to server precomputed results to users rather than hitting the database every time. . In practice I ve found that the speedup usually far outweighs the overhead of using the cache but it depends on your implementation. In this article we will learn about MySQL Query Cache different variables of query cache with commands and examples. Download and install a supported version of MySQL. In the MySQL 4. join_buffer_size. The query cache was also disabled by default starting from MySQL 5. Use this form when tuning your MySQL database server to calculate the maximum MySQL memory usage based on configuration settings used in your my. Clearly saying the result sets are cached against those query sets. If you are engaged to use query caching I suggest to use Redis or ProxySQL. We are using NodeJS with MySQL using pool with 10 connections. The improvement The Query Cache mechanism ignores spaces and comments at the beginning and at the end of the query. You have had 13 753 316 queries where a join could not use an The statement does not remove any queries from the cache. It s possible to disable the MySQL query cache without restarting the server although you also need to edit the configuration file to make the changes stick on restart. In the odd event that a module caches data somewhere else you can check your modules for implementations of hook_flush_caches and see what they remove. But remember that MySQL also makes heavy use of the OSes buffer cache for MyISAM table data for example . If you don 39 t have a Windows Samba domain controller then you need to use whatever the local LAN 39 s authorative name server is. The more connections you allow the more overhead you bring to your server. Remember the minimum default size is 40KB. Apr 14 2015 Reduce your overall MySQL memory footprint for system stability Adjust your join queries to always utilize indexes Variables to adjust MySQL s maximum memory usage is dangerously high Add RAM before increasing MySQL buffer variables querycachesize gt 8M joinbuffersize gt 128. Also check our MySQL Performance Monitor For a database configuration tuning only please look first at our MySQL database health check. Sep 16 2019 Here we set credentials for both the main DB BigQuery and external DB for pre aggregations MySQL . This component has the Count statistic as difference option enabled. The MySQL query cache is a query results cache. The statement does not remove any queries from the cache. It is recommended to set 1MB. Win Win with the cost of one expensive copy query. MySQL. 3 is the number of cached open tables for all threads. You can profile a query by doing following mysql gt SET SESSION profiling 1 mysql gt USE database_name mysql gt SELECT FROM table WHERE column 39 value 39 mysql gt SHOW PROFILES In this case you can however only use IP names in the MySQL privilege tables. Remember long long ago in other databases connection times were REALLY slow. Something else which may be grinding your machine to a halt is plain old disk swapping MySQL memory has been swapped to disk as virtual memory and swapping it back takes some time. query_cache_limit 3M The query_cache_size parameter sets the amount of memory globally available for the query cache. Aug 22 2019 For your read intensive workloads consider using caching methods they will help you decrease the overall load and your concurrent users can grow to 20 000 too Caching can be done on the server via CDN etc. For MySQL there is a general query cache which can help tremendously. None. Download Code or Download PDF. I m using MySQL on the CLI. Now you can set up the MySQL query cache size and type. of your tables should be cached you can use the reverse process ie set nbsp . This command will not remove any queries from the cache unlike RESET QUERY CACHE. SELECT statements that generate a result set that should be cached nbsp 22 Jan 2017 MySQL 39 s query cache is a useful tool to improve performance and scalability. You can meet lots of recommendations for using this cache type and even increasing its size. 4 Nov 2015 How to Improve Magento 39 s performance using MySQL query caching. The query cache stores the text of a SELECT statement together with the corresponding result that was sent to the client. It 39 s one of the most effective methods of improving performance that is quietly handled by the database engine. mysql or the performance_schema database It makes use of user or local The query cache size is allocated in 1024 byte blocks thus it should be set to a nbsp MySQL has a query cache which caches the results of SELECT queries if enabled. 16 on Ubuntu Server 18. This includes both code snippets embedded in the card text and code that is included as a file attachment. 0. One should use the params macro to build a parameters for execution. So I must restart MySQL to make it use no cache. The query_cache_limit variable tells you how big the resultset of a query can be in the cache if a result set is larger then it won 39 t get cached. Yes or No. The sky is the limit for various use cases of working with MySQL with PowerShell queries however for me I had the need to run a scheduled task and query a MySQL table for a return and shoot out email alerts based on the return. As BigQuery acts as a single source of truth and stores all the raw data MySQL can act as cache layer on top of it and store only small aggregated tables and provide us with a desired sub second Aug 27 2009 As I read that page 2 and 3 should give the same value. The resulting performance improvement often is dramatic. For customers with lots of data and or web traffic a round of load testing is also recommended. So I thought I should write a quick tutorial to quickly set up the query cache without going into the details. Now create the user and table mysql gt CREATE USER 39 USER 39 39 39 IDENTIFIED BY The solution is to use the local domain controller as the primary DNS. It will return the difference between two polling intervals. Apr 30 2018 Query Cache Keeps the result of queries in memory until they are invalidated by writes. large instance. quot MySQL is the key component of Verizon Wireless mission critical employee portal application. If query_cache_size is 0 you should also set nbsp I 39 m using a dedicated server with 32GB RAM and an 8 core server using Maria DB 10. query_cache_limit 0 query_cache_size 0. Keeping it optimized and used efficiently can make a big difference in the overall throughput of your application so it 39 s worth taking a look under the hood understanding it and then keeping it tuned optimally. Note the query cache is deprecated in MySQL of 5. r3. If you really want reliable results shut down mysql then dismount and remount the filesystem holding your table and index files between tests to force the OS the release its filesystem buffers. The first time you run a poorly coded query it might take 40 seconds. However MySQL itself provides a cache mechanism which is called Query Cache in which the queries being fired at the database are cached. In this guide we will query MySQL using the PDO object and then force the browser to download the data in an Excel file. query_cache_limit This is the maximum size query in bytes that will be cached. When a query is executed the last result block is trimmed to the actual data size so that unused memory is freed. ronaldbradford. May 08 2018 The short answer is yes you can but you don 39 t want to. 0 2019 07 30 Aug 29 2016 Using your MySQL editor take a look at a query using the EXPLAIN option. quot High performance Mysql quot has a great chapter on the query cache as well See full list on digitalocean. 9 quot or quot if The Hitrate of the Query Cache is calculated from Qcache_hits Qcache_hits Com_select . You might consider this the threads created hit rate. MySQL client MySQL client programs which make it possible to connect to and interact with the server. js should have write access to the stb_pre_aggregations schema where pre aggregation tables will be The good news in MySQL 8. So we planned already for long time to write a script to do this job on a regular base. 168. The following variables should be examined to determine the availability of the query cache. Always use the built in functions whenever possible they are cached to hell and back for exactly this purpose. If the query results exceed the query cache limit the results or data will not be cached. frm files. Oct 20 2015 MySQL users also have a number of caching options to expedite transactions from making more RAM available for the buffer pool used by InnoDB MySQL s default storage engine to enabling the query cache to serve identical queries from memory to using an application level cache such as memcached or Redis. Query Cache MySQL s Jekyll and Hyde of performance tuning options when it is useful it really helps when it hurts it really hurts MySQL Query Cache caches both the query and the full result set query_cache_type Controls behavior 0 or OFF Not used buffer may still be allocated Using the Query Cache. cnf file can cause a serious performance bottleneck in applications with high database read write activity. Another usefull parameter is query_cache_limit the default value for this is 1M it tells MySQL what is the biggest query it should cache you can modify this to fit your needs query_cache_size 16M. To turn OFF QC query_cache_type OFF 0 and query_cache_size 0 to release 67108864 of RAM. If we insert a new record to the cur table MySQL will clear the affected queries and only the affected queries from the cache mysql gt INSERT INTO cur cur_user_text VALUES 39 xxx 39 Query OK 1 row affected 0. The query cache runs in a single thread and can severely limit throughput in a server. By continuing to use this site you are consenting to our use of cookies. There are some restrictions Apr 12 2019 1. Geoff Fawkes Thanks for the reply I m trying to get our MySQL memory footprint down but I don t think I should lower table_definition_cache that low it does reduce memory footprint but it also Cache hit return data from Redis directly with no query to MySQL Cache miss query MySQL to get the data can use read replicas to improve performance save the returned data to Redis return the result to client. query_cache Jan 27 2017 If you have many repetitive queries and your data does not change often use query cache. 20 version and it is removed in MySQL 8. If the size is 0 the cache is disabled even if query_cache_type is not OFF. Named parameters may be repeated within the statement e. When tables are modified any relevant entries in the query cache are flushed. quot Sep 19 2020 This allows you to cache the output of the query used to generate the view or the end HTML output of your View and you can tune the cache for them separately. In the earlier post about MySQL configuration I mentioned two variables query_cache_type and query_cache_size. Caching SELECT NOW for 500ms on the client side would have reduced a lot of unnecessary network round trip. Then if an identical query is received later the MySQL server retrieves the result from the query cache rather than parsing and executing the statement again. bottlenecks . QUERY CACHE. 19 Jan 2015 Note This is part four in our Extending MySQL with PHP 39 s MySQLnd Series. MySQL should have enough RAM to be able to cache the repository and avoid the high Disk I O activity. Slow Query Log The slow MySQL 8. 38 However 254246 queries have been removed from the query cache due to lack of memory Perhaps you should raise query_cache_size MySQL won t cache query results that are larger Nov 05 2014 In this case increase query_cache_limit or query_cache_size or both of them. In MySQL 5. you should use a database table store for the chat account database. If the value of Opened_tables is large and you do not use FLUSH TABLES often which just forces all tables to be closed and reopened then you should increase the value of the table_open_cache variable. 1 and magento 2. Storage Engine InnoDB Using SQL Cache Dependencies C 05 30 2007 25 minutes to read 1 In this article. This also flushes the query cache. Also in order to build pre aggregations inside MySQL Cube. I use MySQL 5. The MySQL table_open_cache or table_cache before MySQL version 5. This was the size on a db. The larger the table the more time that takes. 10 USE demo_schema while with native mysql cli there is no mysql query at all if I issue use demo_schema command Sep 14 2002 If you have more than one apache PHP server connected to the MySQL server the effects can be geometric. If I understand you right then 5 lakh is 500K. Aug 22 2019 Cons No query parallelism. Aug 30 2014 MySQL won 39 t cache query results that are larger than query_cache_limit in size. Here we go PREREQUISITES Before we get started you must have a ubuntu machine with the basic LAMP server configured on it. The query cache is stored completely in memory which of course is the reason for very fast retrievals from query cache. Jan 12 2016 In conclusion the query cache can be really useful even in highly multithreaded environment. 06 sec mysql gt SHOW STATUS LIKE 39 qcache 39 Variable_name Value The defaults value of query_cache_size is 0 which disable the query cache. Following options don 39 t work SELECT SQL_NO_CACHE RESET QUERY CACHE before select FLUSH TABLES before select Somehow there is a cache MySQL will use no matter what I do. Jan 01 2010 Set query_cache_size mysql gt SET GLOBAL query_cache_size 41984 Query OK 0 rows affected 0. For small to medium size database it should set to 16MB to 32MB. It signifies that if you add a space or change a capital letter in your SQL query it will be different from the query cache point of view. Sort buffer seems to be fine JOINS. Before writing about ProxySQL Query Cache let s see what MySQL Query Cache is. It will faster the site or application. If you have many repetitive queries and your data does not change often use query cache. I want to test some queries with and without hitting the cache. If you still have NewRelic monitoring in service the answer for you will be obvious. This ensures faster consecutive results and speeds up execution. Current sort_buffer_size 1 M. This can help you detect problems with your query or table structures e. 18 was just released and it contains a brand new feature to analyze and understand how queries are executed EXPLAIN ANALYZE. Mar 10 2014 I m not sure what version of MySQL I was using at the time and what the original value of table_definition_cache was before I adjusted it. MySQL won t cache query results that are larger than query_cache_limit in size SORT OPERATIONS. 1 . Oct 18 2017 It was a larger problem in some older MySQL versions but I when it is seen now changing table_definition_cache is the solution. query_cache_size. Mar 25 2011 Use an external cache Examining query execution plans EXPLAIN Before trying to optimize a slow query we need to understand what makes it slow. com The Top 20 Design Tips 17. 1 day ago MyISAM Settings query_cache_limit 4M UPD query_cache_size 48M UPD query_cache_type 1 Deprecated variables in new MySQL version after 8. SELECT data into view is the best example of pre cache data using query cache. Sep 11 2014 Sometimes you need get breakdown of a complex mysql query to understand where it is spending most time. js should have write access to the stb_pre_aggregations schema where pre aggregation tables will be Aug 23 2016 About SQL_NO_CACHE . If one sees this error first check the JDBC driver being used to connect to the database server. You 39 ll want to run this command from your MySQL console which will tell you if query nbsp 19 Aug 2017 The MySQL query cache seeks to improve performance at the database level PHP interfaces what are they and when should you use them 12 Mar 2009 MySQL 39 s query cache is an impressive piece of engineering if sometimes misunderstood. 2. Sep 14 2020 Variable_name Value Aborted_clients 0 Aborted_connects 6 Binlog_cache_disk_use 0 Binlog_cache_use 0 Binlog_stmt_cache_disk_use 0 Binlog_stmt_cache_use 0 Bytes_received 187149967 Bytes_sent 539231478 Com_admin_commands 3192 Com_assign_to_keycache 0 Com_alter_db 0 Com_alter_db_upgrade 0 Com_alter_event 0 Com_alter_function 0 Com_alter_instance 0 Com_alter_procedure 0 Com_alter_server 0 Com_alter Oct 12 2006 Each individual query according to the mysql command line client takes 0. The default is 1M. Several other system variables control query cache operation. So here is my little optimized code to get column names from a table without using show columns if possible query_cache_size is the size of the query cache in bytes. Now we finally found some time to do it This step is not necessary if using the method above to apply the settings to a running instance of MySQL however it is necessary to prove the configuration file changes won 39 t cause the service to fail to start on next server service restart. It is important to know how the MySQL query cache works as it has the potential to cause significant performance improvements or a slowdown of your workload. Normally it is wise to set innodb_buffer_pool_size to about 70 of available RAM. August 31 2014 2 21am 2. The maximum size can be 32MB. BTW If you use MyIsam for this temporary table which is the case on MySQL MariaDB uses InnoDB you could simply run a COUNT query on it to get the exact number of elements. It is not a hard limit so ProxySQL may use slightly more memory than that but it is enough to keep the memory utilization under control. THAT S WRONG This is an extremely common misconception and understandably so because query cache sizing depends a lot on your database size database query types the ratio of database reads vs writes database traffic hardware etc. I suspect the performance impact is even higher on MySQL 5. 10. They do say to increase the table_cache quot if you have the memory quot . Query Cache in MySQL is used in scenarios when the same queries need to be executed on the same data set. With analytics queries we usually run a few big SQL queries and the ability of a database to use many cores to run each queries is very important. SELECT SQL_CACHE FROM brille A QC miss will add up to about 20 overhead compared to the same query executed directly without QC lookup. 3 The MySQL Query Cache One should use name as a placeholder syntax for a named parameter. Query cache holds the text of a SELECT statement with a result of the statement that was sent to the client or caller. When using a standard MySQL binary this value is always YES even if query caching is disabled. Query cache based on SQL_ID. x days the query cache was disabled by default for the sake of InnoDB. 00 M. Jun 25 2020 Azure Database for MySQL supports at largest 1 TB in a single data file. Oct 04 2007 QUERY CACHE Query cache is enabled Current query_cache_size 8 M Current query_cache_used 7 M Current query_cach_limit 1 M Current Query cache fill ratio 89. key_buffer_size 16M As there are no MyISAM tables this variable helps with MyISAM temp tables. Query_cache_type must be set to 1 and query_cache_limit must be a reasonable value. When your monitoring alerts you what action will you take Increase QC this may slow things down if you increase it too much. Consult the mysql manual for a complete description would be a larger post . 0 is that the MySQL Team has stopped supporting this as this variable can really cause performance issues. When it stores any data in memory MySQL can access it almost instantly instead of having to go back to the full database on the hard drive and look up the requested data which is slow . 4GB Description If autocommit is off query cache won 39 t serve from the cache the first query that causes a transaction to start. Jun 26 2017 We recently had a user ask us a relatively simple question How do I speed up my MySQL query performance without just relying on the CPU For those who run websites or applications that rely on MySQL databases this is an incredibly important question as it can mean the difference between a smooth experience and one that causes frustration for both you and your users. 7 This comment has been minimized. Queries Registered in Query Cache. The improvement MySQL Query Cache does work well with prepared statements. Oct 22 2013 Perhaps you should raise query_cache_size. BTW. There might be a way using SPIDER storage engine but I haven t dig into that. A temporary table has to be created and filled every time you do the query. Nov 19 2003 The cache cannot stay in memory indefinitely. are setting query_cache_type to 0 in runtime that should eliminate the nbsp 30 May 2017 I 39 m forced to use MySQL at work because it 39 s much easier to work with for If you enable WordPress 39 s object cache it should get most page nbsp 8 Jan 2019 We know that MySQL query cache is deprecated as of MySQL 5. 1. The query cache stores results of SELECT queries enabling the quick return of the query if an identical query is received in the future. Restart your mysqlserver service mysqld restart . If you use the standard built in stuff object caching is built into all aspects of that. You can use the same SQL SELECT command into a PHP function mysql_query . As I read that page 2 and 3 should give the same value. quot But nothing explaining where to go to to set this up in Drupal. Many of the useful task available from USPS require a lot of data. One should use name as a placeholder syntax for a named parameter. Regardless of the platform we can use mSQL quickly. Any well written module that has a cache should prefix it with cache meaning that the answer to your question is quot Yes quot . You can learn more about obtaining BigQuery credentials at the Cube. 15 seconds. Let s say your cache expiry time is 30 minutes. If you have a single table size larger than 1 TB you should use the partition table. 12 Jun 2019 Use the following command to check if query cache is supported show variables like 39 have_query_cache 39 . Run MySQL tuner. This MySQL Performance Tuning Key should give you a guide how to best tune you MySQL database systematically It should also work similar for other RDBMS. On the mysql command line you can determine if the query cache needs to be flushed first look up the Qcache status information Oct 19 2015 By default the query cache is disabled you must enable it. This can be done globally by logging into a nbsp You can monitor it using innodb which will show queries in quot waiting for query cache Or is the mysql query cache just used for simplistic queries anyway enable it for all queries and I assume there 39 ll be a way to say it should be disabled. There is some overhead in running the query cache. This means that frequently used database queries will run much faster because setting permanent the MySQL server configuration file must be modified. With some query cache configurations or server workloads you might When calculating your query cache hit rate you must fetch this value at a nbsp 17 Jun 2011 This leads to a less optimal use of the Query Cache than possible. g. MySQL Query Cache. The maximum memory usage comes from a lot of different settings mostly buffer sizes but it appears that documentations don t clearly state how to find or set this value. Didn 39 t test quot mysql quot driver because is not available in my test server only quot mysqli quot and Nov 09 2015 Today let us focus on some practical aspects of memcached. 2xlarge instance it was set to 2460900352 i. We think that with the correct settings of Apache and MySQL you can get excellent results and the correct level of resource use without installing third party proxy and cache modules. This value is calculated through the difference delta between Qcache_hits and Com_select actual value of the variables minus the value since the last run from check_mysql_health . Unlike MySQL community edition where the query cache is being deprecated and disabled as of version 5. I have already built a web app using mvc and have it connecting to the database. That 39 s why you should either use a web server proxy cache or the static file cache With the query cache turned on MySQL stores SELECT queries and their nbsp This should be adequate for most cases. Mar 28 2020 Optimize the MySQL query cache Almost all optimization in the field of computers comes down to caching. it does work such a dork. MySQL or MariaDB can use only one core per query and keep the others idle. As a final stress test you can enable to determine if there is a benefit. 00 K You have had 18 queries where a join could not use an index Query Cache MySQL s Jekyll and Hyde of performance tuning options when it is useful it really helps when it hurts it really hurts MySQL Query Cache caches both the query and the full result set query_cache_type Controls behavior 0 or OFF Not used buffer may still be allocated Apr 01 2009 The query is parsed. This function returns the row as an associative array a numeric array or both. innodb_buffer_pool_size 128M query_cache_min_res_unit 2k thread_stack 192K Dec 04 2018 One way not to have to run queries is through caching. 8 query_cache_type is set to OFF by default. Query cache is most useful when there are tables that are not expected to change very often. Connection pools could make a real difference. Mar 24 2006 Enable the query cache in MySQL to improve performance. x it can be a toss up. So I ll gloss over this for right now. So if you haven t explicitly turned it ON on old version it may not work anymore Check current status of query_cache mysql e quot show variables like 39 query_cache_ 39 quot Will output something like May 30 2017 The MySQL query cache is a query results cache. It s an acceptable practice to modify it for high throughput demanding workloads. The MySQL query cache enables caching of queries which in theory should speed querying the database up. Closes all open tables and forces all tables in use to be closed. MySQL query cache is a cache mechanism that stores the text of the query and the result of the query into memory. The MySQL query cache is a global one shared among the sessions I had an 850GB mysql db storing mostly demographics data and my query cache was 32M based on my query plan. To optimize MySQL table_open_cache you need to consider lot of factors. 6 on POWER8 I enabled the query cache and ran a benchmark. Features like self management capabilities like auto restart space expansion and automatic configuration changes for ease of management are available in mSQL. What is it EXPLAIN ANALYZE is a profiling tool for your queries that will show you where MySQL spends time on your query and why. In this context caching means execute a MySQL query once and save the result in a temporary file. The query cache system variables all have names that begin with query_cache_. Next update the variables in my. Jun 22 2012 This vm node stores your data in RDBMS such as mysql or postgresql. This blog post is part in the quot Run Different Linux Network Services on Separate Systems VM quot series. cache in MySQL. The Query Caching is one of the caching mechanism used to improve performance. com estimates 13 worst case. I was surprised to see that the query cache was enabled in Aurora. Take a look at the following screenshot of a MySQL table called members As you can see it is just a basic MySQL table with three rows. Sep 17 2019 There are two configuration settings that define how a query cache should be used. For mutable operations create update delete Delete the entry in Redis Create update or delete the data to MySQL. There are some restrictions The query must match byte for byte the query cache avoids parsing Nov 11 2016 The query cache is shared among sessions so a result set generated by one client can be sent in response to the same query issued by another client. The query cache should take up a stable chunk of memory and I would think the InnoDB would too. I have a script that is designed to work with mysql and i need it to work with microsoft sql. Some people who don t do much in the way of repeated reads have complained that the query cache was disastrous for Sep 27 2013 All of this to say that the query cache within mysql is something we generally recommend to keep on. We recommend leaving the query cache enabled unless you re confident that your queries are not cacheable and you want to reclaim the memory for use with other buffers and caches. A part of the ongoing development includes performance enhancements. cnf or by your host. Mat views in MySQL are a Transactions per Second one unit of performance for write operations on a database mysql has a query cache I wouldn 39 t double cache unless you have evidence supporting it being necessary. Add the reserved word EXPLAIN at the beginning of your query to get the execution plan for the query. a MySQL cluster but this is not an easy task and May 09 2018 Test Mysql MySqli and PDO Mysql drivers Reload the pages and confirm in debug console quot Database Queries quot quot Profile quot that each query in run without using db cache Example. Here we set credentials for both the main DB BigQuery and external DB for pre aggregations MySQL . Based on its analysis it may suggest to increase or decrease the query cache. 7. The original acticle is about regulary flushing the MySQL Query Cache as it will fragment over time. Being able to clear the cache is absolutely necessary. And realize too that this means you can cache portions of a page if you are using one or several Views blocks in the page it will just cache that block in the page not the whole page. 2. But it depends on other two MySQL system variables query_cache_type and query_cache_limit. Test 1 Select Values in a Range of May 21 2004 The query cache stores the results of frequently used queries so as to speed up response time a high value here means that MySQL is working efficiently by using the cache instead of rebuilding Oct 22 2009 It s recommended to put this MySQL only extension in a comment to keep with compatibility with SQL standards. In almost all production servers it is wise to turn off the Query cache. 1 information schema plug ins . memcache needs to be installed as a separate server process and cache needs to be managed programatically. So 500K hits per day is 8 hits per second on average which is Ok even for bare MySQL. For this purpose MySQL has a query examination tool called EXPLAIN. This should be adjusted upward as the database increases in size. Notes. To monitor query cache performance use SHOW STATUS to view the cache status variables SHOW STATUS LIKE 39 Qcache 39 The output of this command will look similar to this May 31 2019 3. Both directives should have the same size and will help you prevent disk writes. MySQL is the recommended database server. 0 has removed this query_cache_size setting and if one uses the old JDBC driver to connect to it the issue would occur. Set the cache connection properties in order to use the cache This is a huge performance trick for WordPress like PHP MySQL App. The MySQL is one of the important feature in MySQL and an inevitable part of query optimization. Second Understand the of threads_created versus the connections used. Jul 29 2009 Generally speaking you can tune up MySQL by telling it to cache things in memory. May 22 2014 Clearing a database 39 s or table 39 s cache is CRUCIAL for performance testing. If there is no cached copy MySQL runs our request against the data as normal and caches the result for future use. 12 Jun 2009 The MySQL query cache is used to store data retrieved using The above command should be put in a script that run every 6 hours or so. Reactions Diesan Romero and SyTry Nov 20 2019 Your chat history query should be under 50ms. 1 php fpm with nginx and obtained a few settings to change but among them this one query_cache_size 0 query_cache_type 0 query_cache_limit gt 1M or use smaller result sets I am only running be send in response to the same query issued by another client. When Not to Use the MySQL Query Cache The query cache should be disabled in a server with many fast queries and many CPU cores. Check if memcache is listening on the port on which it was installed netstat ap grep selected_port You have 3900 open tables. Total DB size is less than nbsp 30 May 2017 The query must match byte for byte the query cache avoids parsing Use of non deterministic features will result in the query not being cached nbsp 28 Sep 2015 Although enabled by default you must always verify that query caching is turned on which can be done by checking the server variables. you should use a in memory cache for the connected user list needs to be distributed if you go above one server also requires a bus delivery system for signal r . MySQL Memory Calculator. 13 only. There are some drawbacks for the cron method for flushing the query cache It will only work on UNIX like platforms as MS Windows uses the task scheduler to schedule tasks. A value between 64M to Mar 12 2015 MySQL query cache. Sep 01 2013 Important Note From MySQL 5. Check that SQL_NO_CACHE will force server to don 39 t use query cache locks. If you want to get optimized and speedy response from your MySQL server then you need to add following two configurations directive to your MySQL server The amount of memory SIZE allocated for caching query results. In my opinion the majority of MySQL databases in use will not need a max connections or 1500 or more. This seems to be the case with mysql. It should be set higher than the value for open_tables and the MySQL manual recommends setting the value using the formula table_cache max_connections x N where N is the number of tables in a typical join. Current table_cache hit rate is 2 while 95 of your table cache is in use. The simplest caching strategy is to allow cached data to expire after a specified period of time. mysqltuner. I wish MySQL would spend time in improving key features for example the Query Cache lacks sufficient instrumentation like what queries are in the cache what tables are in the cache and also lack all the sufficient system parameters exposed to fine tune. it is clear the query has been cached and it should execute much nbsp The query cache stores the text of a SELECT statement together with the corresponding result that was sent to the client. Read these to learn more on this MySQL MySQL 5. js docs here. Apr 25 2012 To disable the MySQL query cache for the current running session you need to do the following but keep in mind that it will be enabled automatically on your next restart Open the terminal and sign in to your MySQL server with this command use the password assigned during the installation of the MySQL server All source code included in the card Reset MySQL query cache is licensed under the license stated below. etc. query tcp and dst port 3306 192. Reloads the privileges from the grant tables in the mysql database. 00 seconds before and after optimization so if I didn t profile that query I wouldn t have an effective way to optimize it except watching it run for a while which by the way does not count as profiling . 128M is dangerously high. Jan 29 2019 MySQL makes it possible to examine the performance of the Key Cache by using the SHOW GLOBAL STATUS and SHOW GLOBAL VARIABLES statements and reviewing some specific variables. I You typically want to configure MySQL to use all of the memory resources available as well as to allow the number of connections that your application requires. Oct 17 2019 MySQL 8. arout77. Jun 15 2014 Protip Flushing the query cache with flush query cache does not delete or clear the query cache. Defragment the query cache to better utilise its memory. com enable MySQL Query Cache embedded in MySQL server itself no external dependencies. Nov 07 2018 Since the server had free RAM available setting MySQL Query Cache Size very large would reduce cache prunes thus increasing performance. Not really sure what you 39 re asking it is giving you instructions right there I chose to use a real table instead because I can effectively cache the results. Sep 28 2017 Though MySQL s query cache is pretty helpful in many situations the fact is every entry gets invalidated very fast in an active database rendering it almost useless. Jun 05 2014 While working on MySQL 5. This query cache doesn t suffer from the limitations of the implementation in the community edition. MySQL Query Cache is a very interesting feature that quoting the documentation stores the text of a SELECT statement together with the corresponding result that was sent to the client. I read the ExecuteS function manual and if nothing is specified it should default to use Need to enable query cache as it improves the performance of the execution of queries and it is one of the best methods for database performance. Free Memory in Query Cache MB This counter returns the amount of free memory in MB for the query cache. With the following Query you can see the values for your Query Cache mysql gt nbsp To make queries faster to respond is to use caching a cache stores frequently data should still be in the data cache memory which means for faster retrieval. It will plan the query instrument it and execute it while counting rows and measuring Jan 27 2017 MySQL s query cache is frequently the cause of server stalls as we ve seen with our Adaptive Fault Detection. Caching can improve performance by allowing data to be stored for faster access and the MySQL query cache is no exception. 7 Reference Manual 8. 10k TPS is not that high for this sort of workload you should be able to handle that. May 29 2010 quot The MySQL query cache can improve performance of your site by storing the result of queries. query_cache_size total size of memory available to query caching the default is 128Mb My n00b understanding of query caching is that any writes to tables will remove invalidate from the cache every query which uses that table. Sep 28 2009 My advice is to disable the Query Cache by default especially for testing. I have to agree on their blog that it is unlikely to improve predictability of performance. These can be set in an option file or on the command line when starting mysqld. Increase table_cache gradually to avoid file descriptor limits Your applications are not closing MySQL connections properly Variables to adjust query_cache_size gt 16M tmp_table_size gt 32M max_heap_table_size gt 16M table_cache gt 64 server1 You should carefully read the output especially the recommendations at the end. When the same query is executed multiple times the result is fetched from the cache which is quite fast. Jul 05 2019 Use Cases for Querying MySQL with PowerShell. 3 MySQL 8. First mysql query_cache_size_MB which defines a soft limit on the query cache size. Although it is a bottleneck for any write intensive workload because cache entries are invalidated when the relevant table receives a write. And as folks from Oracle put it look at the full documentation here The query cache stores the text of a SELECT statement together with the corresponding result that was sent to the client. You need to type the following commandss on vm04 having an IP address 192. You can set up the MySQL query_cache_size by using the following command mysql gt SET GLOBAL query_cache_size 40000 Query cache type can determine the behavior of all connections. Reason 2 The query cache allocates blocks with a minimum size given by the query_cache_min_res_unit system variable default value 4096 bytes . different values for bind variables will use the same cached query. query_cache_type. The reason behind that is the fact that threads need to lock the cache during updates. So if query works with current data nbsp 6 Dec 2018 There are two configuration settings that define how a query cache should be used. This capability is instrumental in making sure the Key Cache is performing well. How the query cache uses memory. The query cache is deprecated as of MySQL 5. Therefore each query will reflect the actual performance impact as when it was called for the first time. quot But this is not true in at least one case loading data into the timezone tables does not invalidate cached queries using CONVERT_TZ. You can disable the hostname cache with skip host cache. Remainder Feb 28 2010 The MySQL manual doesn 39 t fall into this trap but if you search Google for Key_read_requests you will find lots of advice on quot tuning by ratio quot including phrases such as quot The ratio of key_reads to key_read_requests should be as low as possible no more than 1 100 quot or quot your key cache hit ratio should be very high ideally above 99. If a query is stored and then an identical query is received in the future it will return results much faster. Luckily MySQL is clever enough to clear it when you make any changes to the tables used in a cache query. Problem Cache Expiry. 3 Apr 2012 The MySQL query cache is a special buffer where database stores the The long_query_time setting tells MySQL how long a query must run nbsp 5 Sep 2012 APC Memcached MySQL Query Cache Drupal sites if you 39 re not already using APC for this purpose you should be unless you 39 re using nbsp 4 Jul 2011 In this article we will learn how optimize queries with Query Cache. 4GB Aug 19 2017 The MySQL query cache seeks to improve performance at the database level by checking incoming queries against it s cache and returning pre stored results when they re available. dst e mysql. I have also restarted my mySQL server with the changed parame Oct 15 2018 So if your application has a high rate load the MySQL cache will be completely useless and in that case it would be better to set these two variables to zero saving the overhead of managing the MySQL cache and instead you can use something like Redis to manage the cache. Current read_rnd_buffer_size 8 M. Its main function is simple it is a giant hash table that associates bulk SQL queries with a group of results. Oct 20 2008 Leverage The Query Cache Query Cache can be a great bene t Deterministic v Non Deterministic SQL Best Practice MySQL Query Cache is not the only type of caching you should consider Presented By Ronald Bradford www. Key cache Cache table indexes. In the profiling stats it shows the query with SQL_NO_CACHE taking 2 3s each however in the module code it 39 s not forced to use sql_no_cache. 4 MAMP . For example a client can disable use of the query cache for its own queries like this mysql gt SET SESSION query_cache_type OFF If you set query_cache_type at server startup rather than at runtime with a SET statement only the numeric values are permitted. 1 and most tables are InnoDB. TABLES. This values are continuously increased. The RESET QUERY CACHE statement removes all query results from the query cache. Leverage The Query Cache Presented By Ronald Bradford www. Restart the MySQL service with the command below to apply changes service mariadb restart 2 gt dev null service mysql restart 2 gt dev null. In MySQL keys are nothing but indexes In oracle keys are constraints if index size is small then it will cache index structure and data leaf. One way you can cache queries is with the MySQL query cache. cnf file. The second time you run it it might come back in. If an identical statement is received later nbsp A value of 2 or DEMAND causes caching of only those statements that begin with SELECT SQL_CACHE . This is a reply on Regularly flushing the MySQL Query Cache. 17 version of MySQL Jul 24 2008 Inspect the Query Cache using MySQL Information Schema Plug ins A while ago I wrote about MySQL 5. Below is a list of scenarios when ideally query caching should not be used. If slow query count stays stable you really do not need QC in service. The account query should be under 40ms. back_log 1500 When MySQL gets a lot of connections in a short time it will keep them in a Why we should use MySQL. You should get an output similar to nbsp 7 Aug 2015 It is also worth noting that many applications run a database workload where writes are light and concurrency is low the query cache should then nbsp 2 Jan 2015 Arunjith Aravindan provides an overview of the MySQL Query Cache explaining how it works and when and when not to use it for workload optimization. You can maximize MySQL cache optimization by caching the content. 04 followed by a practical approach to cache data from MySQL using Memcached and PHP script. At the time I wrote a plug in to report the contents of the query cache but for all kinds of reasons I never found the time to write a decent article about it nor to release the code. It will look up the local SQL Server 39 s IP and pass off any non local lookups to the Internet provider 39 s DNS. Query must be deterministic Query might provide same result no matter how many times it is run if data remains the same. Of course using your session will improve performance a bit and will free up some of mysql 39 s cache for other queries. Focus on what index is being used Write the results to a column row or cache. Sep 26 2013 query cache hit value is not changing in my database InnoDB internals has a very hands on approach to the query cache since it micromanages query cache entry invalidation. 5 and beyond supports a 4 byte utf8 but confusingly must be set The MySQL query cache defaults to a non zero size in some commonly installed nbsp 22 Aug 2017 Hello out of curiosity I run a mysqltuner on my VPS CentoS 7 Which setting you prefer should be based on YOUR comparisons and your nbsp 15 Jun 2014 You have to use reset query cache to fully clear MySQL 39 s query cache. The query cache works as follows The first time a given SELECT statement is executed the server remembers the text of the query and the results that it May 30 2017 And some times it also makes sense to cache query that MySQL QC wouldn 39 t cache. The MySQL query cache is a global one shared among the sessions. 20 Aurora has a reworked query cache. Use your connections efficiently. This can be changed in my. Enabling the query cache reduced performance by an order of magnitude . The Cache Database. How to tune the query cache to balance its benefits against fragmentation pruning and other costs. For every time that same query is executed Read More MySQL query caching using PHP Zend_Cache Nov 11 2010 Some use client level cache some server side cache. For example once I saw an application running SELECT NOW hundreds times per second across multiple clients . cnf will use query_cache_type 0 that is query cache is disabled. This is mainly used to avoid the re execution of commands that were already executed. With query cache. The separate webservers should query the same database and refer to the same filestore and cache areas see Caching but otherwise the separation of the application layers is complete enough to make this kind of clustering feasible. Log into MySQL and run the following Jun 26 2009 MySQL query cache is good to cache select queries and their results and improve some performance of your database applications. Sep 28 2015 The Extra field contains additional information on how MySQL will process the query say by using the WHERE clause by using an index with a temporary table and so on. You can find the values of these status variables in MySQL with SHOW GLOBAL VARIABLES Have_query_cache YES or NO Query_cache_type ON or OFF Sep 16 2007 query_cache_type This value must be ON or 1 for query caching to be enabled by default. cnf MySQL configuration file. This method of query caching can offer us huge performance boosts. After the caching results will be set in a memory cache like memcached or cassandra. This should be set to the folder location where generated labels should be stored. How to understand the query cache s performance fragmentation average query size and other important metrics. If your database size is larger than 1 TB you should create the table in innodb_file_per_table tablespace. If you have a lot of queries with small results the default block size may lead to memory fragmentation as indicated by a nbsp 25 Jun 2009 Problem Statement Many PHP developers using MySQL have unclear a query must meet to take advantage of the query cache Only exact nbsp MySQL 5. 6. Now it s a little smarter and it won t ignore the cache if there are comments at the beginning but it doesn t strip the comments out when calculating the This is a tutorial on how to export MySQL data to an Excel file using PHP. If you do not intend to use the query cache you should set the value of query_cache_size to zero. I ve done my share of work with sprocs cursors and temporary tables in TSQL mostly and I developed a mild hatred for them Aug 28 2018 table_cache sets the amount of memory available for the table cache the total number of tables MySQL can hold open at any given time. Sep 28 2015 The impact of the MySQL query cache can degrade the performance for environments with heavy write to read ratios. Re how to cache mysql query results 807599 Apr 25 2007 9 35 PM in response to 807599 yay. Use MySQL for database server. I had started with a large cache and after a few years of using mysql with much performance tuning and cleaning up queries I dropped it to the 32M and it worked well. by Scott Mitchell. If you want to see how long your database queries actually take you need to disable MySQL 39 s query cache. CPU is being used 69 times per second to complete Qcache_lowmem_prunes. 5 MariaDB for Linux x86_64 using readline 5. Jul 04 2019 If you use the EXPLAIN keyword you can get insight on what MySQL is doing to execute your query. This Magento caching type saves results of the database query executions. The first can turn on the MySQL query cache with a value of ON and the second sets the size to use for the cache. 00 sec mysql SHOW VARIABLES LIKE 39 query_cache_size 39 Variable_name Value query_cache_size 41984 The query_cache_size value is aligned to the nearest 1024 byte block so the value reported may be different from the value that we assign. Review the MySQL documentation to learn more about this May 15 2017 The MySQL query cache was introduced as part of version 4. The MySQL server can use a query cache to speed up processing of SELECT statements that are executed repeatedly. What kinds of workloads benefit from the query cache and when you should just disable it. You should probably increase your table_cache. g SELECT foo foo will require a single named parameter foo that will be repeated on the corresponding positions during statement execution. If this MySQL Database Health Check does NOT solve your problem our specialized Performance Tuning and Using MySQL server InnoDB engine with the default configuration parameters in my. The most important parameters are Jul 29 2016 If the query results exceed the query cache limit the results or data will not be cached. But cacheable queries take out an exclusive lock on MySQL s query cache. e. I want to change my AWS RDS parameter query_cache_type value to 2 I have done it in parameter group dashboard as in the given image. 41 on Mac OS 10. MySQL devel Libraries and header files that come in handy when compiling other programs that use MySQL. BabyWolf 2011 06 07 03 54 15 UTC 5 I think it should be ok to store Perhaps you can use these resources elsewhere MySQL won 39 t cache query results that are larger than query_cache_limit in size SORT OPERATIONS Current sort_buffer_size 2 M Current read_rnd_buffer_size 524 K Sort buffer seems to be fine JOINS Current join_buffer_size 256. There are a few different metrics to consider when evaluating the Key Cache Performance. Jan 02 2015 The MySQL query cache is one of the prominent features in MySQL and a vital part of query optimization. This is due to the coarse nature of the query cache where a change of any data to a given table will result in an invalidation of all SQL statements that are cached that use the table. If you use Percona MySQL wizard by default the generated settings for my. If you have a very slow DNS and many hosts you can get more performance by either disabling DNS lookup with skip name resolve or by increasing the HOST_CACHE_SIZE define default 128 and recompiling mysqld. I started to read up on the table_cache but found the MySQL documentation quite lacking. If the query_cache_size value is set to 0 or you just want to change it you ll need to run the following command keeping in mind that the value is in bytes. a series of database queries are made and the database server must nbsp 16 Sep 2007 Most distributions do but you should check anyway. MySQL checks privileges. FLUSH QUERY CACHE does NOT clear out the query cache it simply defrags it leaving the cached query results in place carpii May 10 39 12 at 21 55 This really helped. i have also built a 7 Nov 2018 Here 39 s what happens with a large MySQL Query Cache Size setting Qcache_not_cached 100 should be as close to 100 as possible. Jan 22 2017 MySQL s query cache is a useful tool to improve performance and scalability. Aug 24 2015 There are a lot of blog posts on the internet which warn you about using the Query Cache in MySQL. We achieved 1400 performance improvement by moving from the MyISAM storage engine to InnoDB upgrading to the latest GA release MySQL 5. table definition cache 4096 Stores table definitions . As we know caching is used to improve performance. Similarly the database could be a cluster of servers e. If the query is found in the cache the results will be pulled from the cache which is much quicker than processing it normally. We can start working on mSQL very quickly as it takes a few minutes for the download to installation. Is this updated to work with the latest magento and mysql versions I 39 m using mysql Ver 15. On a db. Some naive solutions try to use cache expiry or retention policy to handle consistency between MySQL and Redis. MySQL used to ignore using the query cache for anything where the first 6 characters weren t SELECT which is probably why they are putting the comment at the end of the SQL. 1. Dec 04 2015 More seriously though you should not only set the query_cache_size 0 but also it s very important that you set query_cache_type OFF and restart the server when you do that this way MySQL will stop using query cache mutex for all queries even those that wouldn t use the query cache anyway. This step can be really complex because it might involve a call to an LDAP or Active Directory service. The problem is that the server_status is stored in the packets saved by query cache and it can only be served backup if the server_status of the saved query matches the current server_status of the server and the server_status when autocommit is off will only become The query_cache_size specifies the size of the cache you may run some tests to know if the size you are using is the appropiate. Now from the previous output it s clear that in order to execute the query MySQL will need to examine all the rows in two of the named tables. Jan 15 2020 Using the latest version is not always feasible for older and legacy databases. You should know that the query_cache_size is used in conjunction with the query_cache_limit variable. An EXPLAIN query results in showing you which indexes are being utilized how the table is being scanned sorted etc. The output shows exactly which variables you should adjust in the mysqld section on your my. Tuning and update configuration. 5 and using the MySQL Thread Pool to support high concurrent user connections. 0K or always use indexes with joins Nov 14 2011 By using the Cache. The limitation Query Cache does not support prepared statements. Should I breakout the relevant tables in these affected select queries into separate queries If the identical query is not found in the cache the query will be processed normally and then stored along with its result set in the query cache. Opening a table file can require a lot of resources so it s the most reliable decision is to store open tables in the cache. Dec 09 2016 Well one does not simply tells MySQL how much memory it should use. Sep 30 2010 Query cache stores complete result sets of SELECT queries enabling very fast retrievals on query cache hits. MySQL The MySQL database server manages the databases and tables controls user access and processes the SQL queries. First we check if query cache is available and if it is enabled. While MySQL has a query cache built in it has several big problems It includes two built in storage handlers and three that you must compile in . Once you get a general feeling for how many are usually connected at one time set the thread cache to that number. 22 Jun 2015 15 Useful MySQL MariaDB Performance Tuning and Optimization Tips queries and your data does not change often use query cache. Oct 08 2016 root proxysql tshark R mysql. Jun 17 2015 Hello I 39 m having a problem with slow queries using the homecategoryplus module checked enabling profiling . Every modification to a table causes purging of all QC entries for that table. The parameter is pretuned in Aurora and the value is much larger than MySQL default. Current join_buffer_size 1. Jun 11 2020 Tip 8 Query the Cache. I currently use columns and rows. If the value is greater than zero the server allocates that much memory for the query cache even if it is disabled. Although it is a good practice in general to carefully set expiry time and retention policy for your Redis Cluster this is a terrible solution to guarantee consistency. 20 and been recommended to use ProxySQL or other external query cache instead. To ensure this data is easy to input and recall later utilize a cache database to make requests. People often do not understand the concept behind the query_cache_size and set this value to gigabytes which can actually cause degradation in the performance. Recommended setting Default variable value . optimize MySQL tables with mysqlcheck you should already have an nbsp 8 Mar 2013 A derived table query should grab a copy it 39 s important that the SELECT query is always the same of the view from cache and assign it for use nbsp 25 Nov 2013 The software provides a complete website solution together with To configure your MySQL database query cache you need to access the other parameters that you should consider when configuring your MySQL server. if Qcache_free_blocks approaches Qcache_total_blocks 2 your query cache is severely fragmented. Some common performance adjustments may be rendered obsolete by newer versions of MySQL. Most MySQL servers have query caching enabled. php PHP class of the Zend Framework you can relatively easy cache MySQL query results to disk. Are you perhaps thrashing the table with reads Jan 21 2017 table_open_cache_instances 8 Divides the table cache to reduce contention. cnf file as per recommendations provided Query cache. Description The documentation says that quot The query cache does not return stale data. On this optimization process we will go over the Apache core configuration and modules that are part of Apache core. This counter returns the number of queries registered in the query cache. The limitation Queries that begin with spaces or comments are ignored by the Query Cache mechanism. Feb 15 2019 The query cache is deprecated as of MySQL 5. You have to use reset query cache to fully clear MySQL s query cache. First mysql query_cache_size_MB which defines a soft nbsp 22 Oct 2009 With Query Cache the result set from SELECT queries are cached with the second so date and time should be calculated outside of MySQL. Hello out of curiosity I run a mysqltuner on my VPS CentoS 7 MariaDB 10. The query cache would normally be checked at this stage but I ve given the SQL_NO_CACHE instruction. These queries also return the same result. It neither checks the query cache to see whether the result is already there nor stores the query result. It can cause more harm than good and there s a reason why it s been disabled by default in MySQL for more than four years. Start at 70 of total RAM for dedicated server else 10 . Aug 16 2011 query_cache_type 1 query_cache_limit 4M You see we use binary logging as engine InnoDB no locking tables and some RAM related params. should i use mysql query cache