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  • Does the number of rows in mysql table matter?

    - by 1s2a3n4j5e6e7v
    I'm coming up with a web app which will want me to store more than 80 Lakh (8 million) rows. Will it be fine to handle those many number of rows with MySQL without having any performance degradation? Assume my RAM to be 4 GB and Infinity GB Harddisk space. Also, the main fields have been indexed.

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  • MysqlTunner and query_cache_size dilemma

    - by wbad
    On a busy mysql server MySQLTuner 1.2.0 always recommends to add query_cache_size no matter how I increase the value (I tried up to 512MB). On the other hand it warns that : Increasing the query_cache size over 128M may reduce performance Here are the last results: >> MySQLTuner 1.2.0 - Major Hayden <[email protected]> >> Bug reports, feature requests, and downloads at http://mysqltuner.com/ >> Run with '--help' for additional options and output filtering -------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [OK] Currently running supported MySQL version 5.5.25-1~dotdeb.0-log [OK] Operating on 64-bit architecture -------- Storage Engine Statistics ------------------------------------------- [--] Status: +Archive -BDB -Federated +InnoDB -ISAM -NDBCluster [--] Data in InnoDB tables: 6G (Tables: 195) [--] Data in PERFORMANCE_SCHEMA tables: 0B (Tables: 17) [!!] Total fragmented tables: 51 -------- Security Recommendations ------------------------------------------- [OK] All database users have passwords assigned -------- Performance Metrics ------------------------------------------------- [--] Up for: 1d 19h 17m 8s (254M q [1K qps], 5M conn, TX: 139B, RX: 32B) [--] Reads / Writes: 89% / 11% [--] Total buffers: 24.2G global + 92.2M per thread (1200 max threads) [!!] Maximum possible memory usage: 132.2G (139% of installed RAM) [OK] Slow queries: 0% (2K/254M) [OK] Highest usage of available connections: 32% (391/1200) [OK] Key buffer size / total MyISAM indexes: 128.0M/92.0K [OK] Key buffer hit rate: 100.0% (8B cached / 0 reads) [OK] Query cache efficiency: 79.9% (181M cached / 226M selects) [!!] Query cache prunes per day: 1033203 [OK] Sorts requiring temporary tables: 0% (341 temp sorts / 4M sorts) [OK] Temporary tables created on disk: 14% (760K on disk / 5M total) [OK] Thread cache hit rate: 99% (676 created / 5M connections) [OK] Table cache hit rate: 22% (1K open / 8K opened) [OK] Open file limit used: 0% (49/13K) [OK] Table locks acquired immediately: 99% (64M immediate / 64M locks) [OK] InnoDB data size / buffer pool: 6.1G/19.5G -------- Recommendations ----------------------------------------------------- General recommendations: Run OPTIMIZE TABLE to defragment tables for better performance Reduce your overall MySQL memory footprint for system stability Increasing the query_cache size over 128M may reduce performance Variables to adjust: *** MySQL's maximum memory usage is dangerously high *** *** Add RAM before increasing MySQL buffer variables *** query_cache_size (> 192M) [see warning above] The server has 76GB ram and dual E5-2650. The load is usually below 2. I appreciate your hints to interpret the recommendation and optimize the database configs.

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  • Sorting mysql array value after string chars swapped from fetched DB data.

    - by Shail Patel
    I want to sort one column fetched from mysql DB, and stored in an array. After fetching I am doing below steps. 1- DB Fetching fields array in row format. ->Field1, Field2, Field3, Field4, Field5 2- From that fields array One columns data [Field3], swapping string keywords. eg. AB013, DB131, RS001 to->013AB, 131DB, 001RS Now I want to sort above value in new string format like-> 001RS, 013AB, 131DB

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  • Why does this simple MySQL procedure take way too long to complete?

    - by Howard Guo
    This is a very simple MySQL stored procedure. Cursor "commission" has only 3000 records, but the procedure call takes more than 30 seconds to run. Why is that? DELIMITER // DROP PROCEDURE IF EXISTS apply_credit// CREATE PROCEDURE apply_credit() BEGIN DECLARE done tinyint DEFAULT 0; DECLARE _pk_id INT; DECLARE _eid, _source VARCHAR(255); DECLARE _lh_revenue, _acc_revenue, _project_carrier_expense, _carrier_lh, _carrier_acc, _gross_margin, _fsc_revenue, _revenue, _load_count DECIMAL; DECLARE commission CURSOR FOR SELECT pk_id, eid, source, lh_revenue, acc_revenue, project_carrier_expense, carrier_lh, carrier_acc, gross_margin, fsc_revenue, revenue, load_count FROM ct_sales_commission; DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1; DELETE FROM debug; OPEN commission; REPEAT FETCH commission INTO _pk_id, _eid, _source, _lh_revenue, _acc_revenue, _project_carrier_expense, _carrier_lh, _carrier_acc, _gross_margin, _fsc_revenue, _revenue, _load_count; INSERT INTO debug VALUES(concat('row ', _pk_id)); UNTIL done = 1 END REPEAT; CLOSE commission; END// DELIMITER ; CALL apply_credit(); SELECT * FROM debug;

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  • How can I tell when a MySQL table was last updated?

    - by RaGE
    In the footer of my page, I would like to add something like "last updated the xx/xx/200x"; with this date being the last time a certain mySQL table has been updated. What is the best way to do that ? Is there a function to retrieve the date ? Should I make an access to the database everytime my footer is displayed ?

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  • SELECT product from subclass: How many queries do I need?

    - by Stefano
    I am building a database similar to the one described here where I have products of different type, each type with its own attributes. I report a short version for convenience product_type ============ product_type_id INT product_type_name VARCHAR product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id ... (common attributes to all product) magazine ======== magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id ... (magazine-specific attributes) web_site ======== web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id ... (web-site specific attributes) This way I do not need to make a huge table with a column for each attribute of different product types (most of which will then be NULL) How do I SELECT a product by product.product_id and see all its attributes? Do I have to make a query first to know what type of product I am dealing with and then, through some logic, make another query to JOIN the right tables? Or is there a way to join everything together? (if, when I retrieve the information about a product_id there are a lot of NULL, it would be fine at this point). Thank you

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  • How to make phpMyAdmin ask for my username and password

    - by anitha
    I am using rhel 5 and php 5 with mysql 5. My server is already configured and running all applications smoothly. I am accessing mysql as root and supplying my password. However, when I access phpmyadmin through browser, it is not asking for my password. Somebody please tell me how can I set it to prompt for username and password. Since I am not familiar with php and mysql please tell me how to do it in simple way.

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  • restrict the scope of variables in a mysql query? with brackets?

    - by Haroldo
    I can't remember what the method is meant to be for ensuring the scope of a variable in a query is restricted to prevent mysql injection. where should i put brackets in the following examples? UPDATE table SET col_1 = '$var', col_2 = '$var2' WHERE col_1 = '$var3' and SELECT * FROM table WHERE WHERE col_1 >= '$var1' (Obviously looking for answers not using PDO!)

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  • Is there a way to listen for changes in an MySQL database table using Java and JDBC?

    - by adrian7
    I have a number of users which are logged in at a time in my desktop application. They are working on the same table (create, read, update, delete data) so I have to update their views, to reflect changes, every few seconds - currently I am thinking to use a different thread to do that. I am using the MySQL database engine. Is there a way, using JDBC, to listen for changes on a specific table in the database and triggering a Java method only when changes are made?

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