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Post-merge fixes and code cleanup

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unknown 2003-12-18 21:07:19 +03:00
commit 06564b43c5
6 changed files with 65 additions and 44 deletions
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34
sql/uniques.cc
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@ -76,11 +76,13 @@ Unique::Unique(qsort_cmp2 comp_func, void * comp_func_fixed_arg,
#define M_PI 3.14159265358979323846
#endif
#define M_E (exp(1))
#ifndef M_E
#define M_E (exp((double)1.0))
#endif
inline double log2_n_fact(double x)
{
return (2 * ( ((x)+1) * log(((x)+1)/M_E) + log(2*M_PI*((x)+1))/2 ) / log(2));
return (2 * (((x)+1)*log(((x)+1)/M_E) + log(2*M_PI*((x)+1))/2 ) / log(2));
}
/*
@ -127,8 +129,8 @@ static double get_merge_buffers_cost(uint* buff_sizes, uint elem_size,
actions.
RETURN
>=0 Cost of merge in disk seeks.
<0 Out of memory.
>=0 Cost of merge in disk seeks.
<0 Out of memory.
*/
static double get_merge_many_buffs_cost(MEM_ROOT *alloc,
uint maxbuffer, uint max_n_elems,
@ -174,7 +176,8 @@ static double get_merge_many_buffs_cost(MEM_ROOT *alloc,
key_size using max_in_memory_size memory.
RETURN
Use cost as # of disk seeks.
>=0 Cost in disk seeks.
<0 Out of memory.
NOTES
cost(using_unqiue) =
@ -229,19 +232,28 @@ double Unique::get_use_cost(MEM_ROOT *alloc, uint nkeys, uint key_size,
result+= n_full_trees * log2_n_fact(max_elements_in_tree);
result /= TIME_FOR_COMPARE_ROWID;
/* Calculate cost of merging */
DBUG_PRINT("info",("unique trees sizes: %u=%u*%lu + %lu", nkeys,
n_full_trees, n_full_trees?max_elements_in_tree:0,
last_tree_elems));
if (!n_full_trees)
return result;
/* There is more then one tree and merging is necessary. */
/* Add cost of writing all trees to disk. */
/*
There is more then one tree and merging is necessary.
First, add cost of writing all trees to disk.
*/
result += n_full_trees * ceil(key_size*max_elements_in_tree / IO_SIZE);
result += ceil(key_size*last_tree_elems / IO_SIZE);
/* Cost of merge */
result += get_merge_many_buffs_cost(alloc, n_full_trees,
max_elements_in_tree,
last_tree_elems, key_size);
double merge_cost= get_merge_many_buffs_cost(alloc, n_full_trees,
max_elements_in_tree,
last_tree_elems, key_size);
if (merge_cost < 0.0)
return merge_cost;
result += merge_cost;
/*
Add cost of reading the resulting sequence, assuming there were no
duplicate elements.