pt-table-checksum SELECT MIN MAX for char chunking is wrong
Bug #821688 reported by
Daniel Nichter
This bug affects 1 person
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| Percona Toolkit moved to https://jira.percona.com/projects/PT |
Fix Released
|
High
|
Daniel Nichter | ||
Bug Description
Imported from http://
The code does "SELECT MIN(id), MAX(id) FROM `db`.`table` ORDER BY `id`" but Baron says:
The query doesn't really make sense. MIN() and MAX() will return a single row, so the query is really a GROUP BY over the whole table; therefore ORDER BY is not needed (you can't order a single row). Is that ORDER BY what's causing the problem? Otherwise, MIN and MAX from an index should be really fast -- we should see "SELECT tables optimized away" in the Extra column of EXPLAIN.
| Changed in percona-toolkit: | |
| milestone: | none → 1.0.1 |
| assignee: | nobody → Daniel Nichter (daniel-nichter) |
Revision history for this message
| Baron Schwartz (baron-xaprb) wrote | #1 |
Revision history for this message
| Daniel Nichter (daniel-nichter) wrote | #2 |
| Changed in percona-toolkit: | |
| status: | New → Fix Committed |
| Changed in percona-toolkit: | |
| status: | Fix Committed → Fix Released |
Revision history for this message
| Shahriyar Rzayev (rzayev-sehriyar) wrote | #3 |
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Daniel,
I think we should simply remove the chunking code and change the tool to using Nibble. I'll post my ideas about this elsewhere.