Bug #15204 5.0 Crashes when selecting from imported data
Submitted: 23 Nov 2005 21:15 Modified: 2 Dec 2005 3:53
Reporter: Kolbe Kegel Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server Severity:S1 (Critical)
Version:5.0.16 OS:Linux (Linux)
Assigned to: Sergey Petrunya CPU Architecture:Any

[23 Nov 2005 21:15] Kolbe Kegel
Description:
Importing certain data from an SQL dump and executing certain queries against that data can cause a crash.

How to repeat:
See private note.

Suggested fix:
n/a
[25 Nov 2005 9:32] Bugs System
A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/internals/32703
[25 Nov 2005 20:34] Sergey Petrunya
The fix has been pushed into 5.0.17 tree.

Description for the changelog:
Running a query could cause the server to crash if:

 * the query reads some table tbl and the optimizer was able to infer the condition in form "tbl.f1 = c1 AND tbl.f2= c2 AND ... tbl.fN=cN" for table tbl.
 * table tbl has an index that covers fields {f1, ..., fN} and ref(c1, c2, ... cN); "using index" can be used to access table tbl.
 * besides that, tbl has set of indexes, neither of which covers {f1,...fN} but taken together they cover this set.
 * The record count estimates for accessing the table using the above indexes have some particular values (the criteria is very difficult to formulate)

The fix is that such queries no longer crash the server.
[25 Nov 2005 20:36] Sergey Petrunya
An error, in previous comment the passage
" * besides that, tbl has set of indexes, neither of which covers {f1,...fN} but
taken together they cover this set."

should be:

" * besides that, tbl has other indexes that cover some of {f1,...fN} fields."
[2 Dec 2005 3:53] Paul Dubois
Noted in 5.0.17 changelog.