# "Multimap" Text Find Timing Test with Small Average Secondary-Key to Primary-Key Ratio

## Description

This test inserts a number of pairs into a container. The first item of each pair is a string from an arbitrary text [wickland96thirty], and the second is a uniform i.i.d.integer. The container is a "multimap" - it considers the first member of each pair as a primary key, and the second member of each pair as a secondary key (see Motivation::Associative Containers::Alternative to Multiple Equivalent Keys). There are 400 distinct primary keys, and the ratio of secondary keys to primary keys ranges from 1 to 5.

The test measures the average find-time as a function of the number of values inserted. For `pb_ds`'s containers, it finds the secondary key from a container obtained from finding a primary key. For the native multimaps, it searches a range obtained using `std::equal_range` on a primary key.

(The test was executed with `multimap_text_find_timing_test` thirty_years_among_the_dead_preproc.txt 400 1 1 6)

## Purpose

The test checks the find-time scalability of different "multimap" designs (see Motivation::Associative Containers::Mapping Semantics).

## Results

Figures NTG, NTM, and NTL show the results for "multimaps" which use a tree-based container for primary keys, in g++, msvc++, and local, respectively; Figures NHG, NHM, and NHL show the results for "multimaps" which use a hash-based container for primary keys, in g++, msvc++, and local, respectively.

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NTG: NHG Native and primary tree-based multimap types find timing test - g++

In the above figure, the names in the legends have the following meaning:

1. n_mmap- `std::multimap`
2. rb_tree_mmap_lu_mtf_set- `tree` with `Tag` = `rb_tree_tag` , and `Node_Update` = `null_tree_node_update` , mapping each key to `list_update` with `Update_Policy` = `move_to_front_lu_policy`
3. rb_tree_mmap_cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_set- `tree` with `Tag` = `rb_tree_tag` , and `Node_Update` = `null_tree_node_update` , mapping each key to `cc_hash_table` with `Comb_Hash_Fn` = `direct_mask_range_hashing` , and `Resize_Policy` = `hash_standard_resize_policy` with `Size_Policy` = `hash_exponential_size_policy` , and `Trigger_Policy` = `hash_load_check_resize_trigger` with αmin = 1/8 and αmax = 1/2

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NTM: NHM Native and primary tree-based multimap types find timing test - msvc++

In the above figure, the names in the legends have the following meaning:

1. n_mmap- `std::multimap`
2. rb_tree_mmap_lu_mtf_set- `tree` with `Tag` = `rb_tree_tag` , and `Node_Update` = `null_tree_node_update` , mapping each key to `list_update` with `Update_Policy` = `move_to_front_lu_policy`
3. rb_tree_mmap_cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_set- `tree` with `Tag` = `rb_tree_tag` , and `Node_Update` = `null_tree_node_update` , mapping each key to `cc_hash_table` with `Comb_Hash_Fn` = `direct_mask_range_hashing` , and `Resize_Policy` = `hash_standard_resize_policy` with `Size_Policy` = `hash_exponential_size_policy` , and `Trigger_Policy` = `hash_load_check_resize_trigger` with αmin = 1/8 and αmax = 1/2

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NTL: Native and primary tree-based multimap types find timing test - local

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NHG: Native and primary hash-based multimap types find timing test - g++

In the above figure, the names in the legends have the following meaning:

1. n_hash_mmap- `__gnucxx::hash_multimap`
2. cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_mmap_lu_mtf_set- `cc_hash_table` with `Comb_Hash_Fn` = `direct_mask_range_hashing` , and `Resize_Policy` = `hash_standard_resize_policy` with `Size_Policy` = `hash_exponential_size_policy` , and `Trigger_Policy` = `hash_load_check_resize_trigger` with αmin = 1/8 and αmax = 1/2, mapping each key to `list_update` with `Update_Policy` = `move_to_front_lu_policy`
3. cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_mmap_cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_set- `cc_hash_table` with `Comb_Hash_Fn` = `direct_mask_range_hashing` , and `Resize_Policy` = `hash_standard_resize_policy` with `Size_Policy` = `hash_exponential_size_policy` , and `Trigger_Policy` = `hash_load_check_resize_trigger` with αmin = 1/8 and αmax = 1/2, mapping each key to `cc_hash_table` with `Comb_Hash_Fn` = `direct_mask_range_hashing` , and `Resize_Policy` = `hash_standard_resize_policy` with `Size_Policy` = `hash_exponential_size_policy` , and `Trigger_Policy` = `hash_load_check_resize_trigger` with αmin = 1/8 and αmax = 1/2

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NHM: Native and primary hash-based multimap types find timing test - msvc++

In the above figure, the names in the legends have the following meaning:

1. n_hash_mmap- `stdext::hash_multimap`
2. cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_mmap_lu_mtf_set- `cc_hash_table` with `Comb_Hash_Fn` = `direct_mask_range_hashing` , and `Resize_Policy` = `hash_standard_resize_policy` with `Size_Policy` = `hash_exponential_size_policy` , and `Trigger_Policy` = `hash_load_check_resize_trigger` with αmin = 1/8 and αmax = 1/2, mapping each key to `list_update` with `Update_Policy` = `move_to_front_lu_policy`
3. cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_mmap_cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_set- `cc_hash_table` with `Comb_Hash_Fn` = `direct_mask_range_hashing` , and `Resize_Policy` = `hash_standard_resize_policy` with `Size_Policy` = `hash_exponential_size_policy` , and `Trigger_Policy` = `hash_load_check_resize_trigger` with αmin = 1/8 and αmax = 1/2, mapping each key to `cc_hash_table` with `Comb_Hash_Fn` = `direct_mask_range_hashing` , and `Resize_Policy` = `hash_standard_resize_policy` with `Size_Policy` = `hash_exponential_size_policy` , and `Trigger_Policy` = `hash_load_check_resize_trigger` with αmin = 1/8 and αmax = 1/2

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NHL: Native and primary hash-based multimap types find timing test - local

## Observations

See Observations::Mapping-Semantics Considerations.