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kaa@polly.(none) authored
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.
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