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Editorial Team
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Asked: 2026-05-26T19:37:28+00:00

I recently upgrade a Joomla! installation from 1.5 to 1.7 with a large dataset

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I recently upgrade a Joomla! installation from 1.5 to 1.7 with a large dataset of articles and while the upgrade method was upgrading the database (inserting content to another table, basically) I noticed that the Rows column value was prefixed with a tilde (~):

See image

Now, at first sight I assume this means that the value is approximate because when I refresh the page I see a different value, sometimes higher, sometimes lower. OK, lets say the value is approximate, in that case, what is causing that? Some considerations:

  • OS: Windows 7.
  • Server: Apache 2 with PHP 5.3 and MySQL 5.1.50-community.
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  1. Editorial Team

    The row count is an approximation used for query optimisation by InnoDB. doing a count(*) is a lot more inefficient and having a rough idea of the number of rows is sufficient to optimise the query plan. phpMyAdmin will be doing a “show table status” query to get the information about the table:

    http://dev.mysql.com/doc/refman/5.0/en/show-table-status.html

    For other storage engines, such as InnoDB, this value is an
    approximation, and may vary from the actual value by as much as 40 to
    50%. In such cases, use SELECT COUNT(*) to obtain an accurate count.

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