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Asked: 2026-05-18T22:21:18+00:00

I have two tables TABLE A and TABLE B. TABLE A contain 1 million

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I have two tables TABLE A and TABLE B.
TABLE A contain 1 million (1,000,000) records and 4 fields while TABLE 2 contain 60,000 and 3 fields.
I am running a query which joins these two tables and usees WHERE clause to find specific products like WHERE product like ‘%Bags%’ and product like ‘Bags%’ e.t.c.

When I run the query directly in phpMyAdmin then it returns records in around 1 or 2 seconds. But when they are being used on website, they are sometime taking 9 or 10 seconds according to MySQL ‘slow query’ log. Actually my website response was very slow at times so upon investigation I found out it is due to MySQL as I came to know about ‘slow query log’.

The slow query log consists of all SQL statements that took more than long_query_time seconds to execute and required at least min_examined_row_limit rows to be examined.

So according to that log “query_time” for above query was 13 seconds while in some cases they even had “query_time” exceeding 50 seconds.

Both my tables are using PRIMARY keys as well as INDEXES. So I want to know how can I optimize them more or is there any way I can optimize MySQL settings in general?

This slowness of website doesn’t happen all the time but sometimes (may be once in a week) and lasts for around 1 or 2 minutes. It gets decent amount of traffic and there are many other queries too, the above I posted was just one example.

Thanks

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1 Answer

  1. Editorial Team

    For all things MySQL and performance related, check out http://www.mysqlperformanceblog.com/

    Check your queries with EXPLAIN, see here and here for info on how to use EXPLAIN as query diagnostic tool.

    It’s not enough to just have indexes. Are you indexing the fields searched in the WHERE clause? Also do you have indexes for the fields used in the WHERE clause (including the fields you mention in ORDER BY, GROUP BY, and HAVING clauses as well as JOINs)? If you have grouped fields in a single index, that index won’t be hit unless you have a query that searches all those fields together. If you group fields in an index make sure they the index will actually be used in your query (EXPLAIN is your friend).

    That said, it could be many other things as well: poorly configured MySQL server, poorly tuned server, bad schema. But your queries and your indexes are good place to start your investigation.

    Here is a nice summary of performance best practices from Jay Pipes of MySQL.

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