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Fix for bug #31207: Test "join_nested" shows different strategy on IA64

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CPUs / Intel's ICC compile

The bug is a combination of two problems:

1. IA64/ICC MySQL binaries use glibc's qsort(), not the one in mysys.

2. The order relation implemented by join_tab_cmp() is not transitive,
i.e. it is possible to choose such a, b and c that (a < b) && (b < c)
but (c < a). This implies that result of a sort using the relation
implemented by join_tab_cmp() depends on the order in which
elements are compared, i.e. the result is implementation-specific. Since
choose_plan() uses qsort() to pre-sort the
join tables using join_tab_cmp() as a compare function, the results of
the sorting may vary depending on qsort() implementation.

It is neither possible nor important to implement a better ordering
algorithm in join_tab_cmp(). Therefore the only way to fix it is to
force our own qsort() to be used by renaming it to my_qsort(), so we don't depend
on linker to decide that.

This patch also "fixes" bug #20530: qsort redefinition violates the
standard.
This commit is contained in:
kaa@polly.(none)
2007-10-17 20:08:58 +04:00
parent 80a2d47b22
commit 6d1f3e8de5
21 changed files with 62 additions and 46 deletions
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2
libmysql/Makefile.shared
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@ -73,7 +73,7 @@ sqlobjects = net.lo
sql_cmn_objects = pack.lo client.lo my_time.lo
# Not needed in the minimum library
mysysobjects2 = my_lib.lo
mysysobjects2 = my_lib.lo mf_qsort.lo
mysysobjects = $(mysysobjects1) $(mysysobjects2)
target_libadd = $(mysysobjects) $(mystringsobjects) $(dbugobjects) \
$(sql_cmn_objects) $(vio_objects) $(sqlobjects)