Re: Limitation of SQL when making LEFT JOIN
Keith C. Ivey wrote: On 21 Nov 2002, at 8:46, Juan C. P. Garrido wrote: When I make the LEFT JOIN between the two tables, it takes a long time, and it seems that the machine is crashed , because everything I try to make in the machine is extremely slow, so I have to reset it manually. Do you have indexes on the columns you're using for the join? Can you show the output of EXPLAIN on your query? Thanks you for your response. Really one of the tables was without index and for this reason the query with LEFT JOIN was so slow. Thanks, Juan - Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
re: Limitation of SQL when making LEFT JOIN
Juan, Thursday, November 21, 2002, 12:46:55 PM, you wrote: JCPG> Iam using MySQL version 4.0.5 in Windows and I want to make a JOIN between JCPG> two tables that have approximately 20,000 records and 20 columns. As all JCPG> the records JCPG> from one of the tables must appear in the result of the SQL( the tables JCPG> donnt have the same JCPG> number of records) , I ought to use a LEFT JOIN. JCPG> When I make the LEFT JOIN between the two tables, it takes a long time, JCPG> and it seems that the machine is crashed , because everything I try to make JCPG> in the machine is extremely slow, so I have to reset it manually. JCPG> Is this a limitation of MySQL when making a LEFT JOIN between two tables JCPG> with a JCPG> certain number of records or is there a different way to solve this JCPG> problem in order to JCPG> increase the speed of the query ? Show me your query? What are the tables structure? What is the output of EXPLAIN SELECT? -- For technical support contracts, goto https://order.mysql.com/?ref=ensita This email is sponsored by Ensita.net http://www.ensita.net/ __ ___ ___ __ / |/ /_ __/ __/ __ \/ /Egor Egorov / /|_/ / // /\ \/ /_/ / /__ [EMAIL PROTECTED] /_/ /_/\_, /___/\___\_\___/ MySQL AB / Ensita.net <___/ www.mysql.com - Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
Re: Limitation of SQL when making LEFT JOIN
On 21 Nov 2002, at 8:46, Juan C. P. Garrido wrote: > When I make the LEFT JOIN between the two tables, it takes a long time, > and it seems that the machine is crashed , because everything I try to make > in the machine is extremely slow, so I have to reset it manually. Do you have indexes on the columns you're using for the join? Can you show the output of EXPLAIN on your query? -- Keith C. Ivey <[EMAIL PROTECTED]> Tobacco Documents Online http://tobaccodocuments.org Phone 202-667-6653 - Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
Limitation of SQL when making LEFT JOIN
Hi, I´m using MySQL version 4.0.5 in Windows and I want to make a JOIN between two tables that have approximately 20,000 records and 20 columns. As all the records from one of the tables must appear in the result of the SQL( the tables don´t have the same number of records) , I ought to use a LEFT JOIN. When I make the LEFT JOIN between the two tables, it takes a long time, and it seems that the machine is crashed , because everything I try to make in the machine is extremely slow, so I have to reset it manually. Is this a limitation of MySQL when making a LEFT JOIN between two tables with a certain number of records or is there a different way to solve this problem in order to increase the speed of the query ? Thanks, Juan - Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
