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Count rows only if needed #14607

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mvorisek opened this issue Sep 6, 2018 · 1 comment · Fixed by #14821
Closed

Count rows only if needed #14607

mvorisek opened this issue Sep 6, 2018 · 1 comment · Fixed by #14821
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@MauricioFauth
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enhancement A feature request for improving phpMyAdmin has-pr An issue that has a pull request pending that may fix this issue. The pull request may be incomplete help wanted
Milestone
4.9.0.1

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@mvorisek
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mvorisek commented Sep 6, 2018 •
edited

Currently the PhpMyAdmin counts the total rows of a query result every time when LIMIT is not present.

If LIMIT is not presented in the user query, default LIMIT (like LIMIT 0, 50) is appended to the query.

But currently the total rows count is queried even when the total rows are below the default limit. This is not needed as has very large impact on long running queries.


Example:

User query:

SELECT count(*) tablewith10megrows


PhpMyAdmin sends to DB:

SELECT count(*) tablewith10megrows LIMIT 0, 50

and gets exactly one row.

But the PhpMyAdmin sends additional unneeded query:

SELECT SQL_CALC_FOUND_ROWScount(*) tablewith10megrows

which is never needed if the rows count of the previous query was below the limit (exactly below max. count as LIMIT clause can have offset).
@williamdes williamdes added enhancement A feature request for improving phpMyAdmin help wanted labels Nov 20, 2018
@dhyey35
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dhyey35 commented Dec 28, 2018

@williamdes I will try to solve this issue and will ask for your help if needed

@dhyey35 dhyey35 mentioned this issue Dec 28, 2018
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@williamdes williamdes added the has-pr An issue that has a pull request pending that may fix this issue. The pull request may be incomplete label Dec 28, 2018
MauricioFauth pushed a commit that referenced this issue Mar 5, 2019
@dhyey35 @MauricioFauth
Fix #14607 - Count rows only if needed (#14821)
feca784 
Signed-off-by: Dhyey Thakore <dhyey35@gmail.com>
MauricioFauth pushed a commit that referenced this issue Mar 5, 2019
@dhyey35 @MauricioFauth
Fix #14607 - Count rows only if needed (#14821)
7d66500 
Signed-off-by: Dhyey Thakore <dhyey35@gmail.com>
(cherry picked from commit feca784)
Signed-off-by: Maurício Meneghini Fauth <mauriciofauth@gmail.com>
MauricioFauth added a commit that referenced this issue Mar 5, 2019
@MauricioFauth
Add ChangeLog entry for #14607
ab3cc97 
[ci skip]

Signed-off-by: Maurício Meneghini Fauth <mauriciofauth@gmail.com>
@MauricioFauth MauricioFauth self-assigned this Mar 5, 2019
@MauricioFauth MauricioFauth added this to the 4.8.6 milestone Mar 5, 2019
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@MauricioFauth MauricioFauth

Labels
enhancement A feature request for improving phpMyAdmin has-pr An issue that has a pull request pending that may fix this issue. The pull request may be incomplete help wanted
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4.9.0.1
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Fix 14607 - Count rows only if needed dhyey35/phpmyadmin
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@MauricioFauth @mvorisek @williamdes @dhyey35