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An algorythm to compare SQL Primary keys and sync A -> B.
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| # -*- coding: utf-8 -*- | |
| import random | |
| def compare(all_read_pks, all_write_pks): | |
| """This function emulates a mathematical problem i try to solve. | |
| I have primary keys from a SQL Table A and primary_keys in SQL Table B. | |
| This function should compare B with A and sync all primary_keys changes to B. | |
| The biggest problem is here that i have to compare numbers in blocks and compare | |
| a single block until its fully synced. | |
| """ # noqa | |
| block_size = 100 | |
| compared = 0 | |
| to_compare = len(all_read_pks) | |
| if len(all_write_pks) > len(all_read_pks): | |
| to_compare = len(all_write_pks) | |
| while compared < to_compare: | |
| read_pks = set(list(all_read_pks)[compared:compared + block_size]) | |
| write_pks = set(list(all_write_pks)[compared:compared + block_size]) | |
| if read_pks == write_pks: | |
| compared += block_size | |
| continue | |
| matching = read_pks & write_pks | |
| for i in write_pks - matching: | |
| all_write_pks.remove(i) | |
| for i in read_pks - write_pks: | |
| all_write_pks.add(i) | |
| if read_pks == write_pks: | |
| compared += len(read_pks) | |
| continue | |
| return all_read_pks == all_write_pks | |
| if __name__ == '__main__': | |
| seta = set(range(1000)) | |
| setb = set(range(1000)) | |
| # Remove random rows from both sets "tables" | |
| numbers1 = set(random.sample(range(1000), 500)) | |
| numbers2 = set(random.sample(range(500, 1000), 250)) | |
| # Compare with 500 random rows removed from both tables. | |
| print("Remove in both is: ", compare(seta - numbers1, setb - numbers2)) | |
| # Compare with 500 random rows removed from source only | |
| print("Remove in source is: ", compare(seta - numbers1, setb)) | |
| # Compare with 500 random rows removed from target only | |
| print("Remove in target is: ", compare(seta, setb - numbers2)) |
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