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mysql_database_helper.py
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mysql_database_helper.py
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import os, uuid, csv
import config_reader
from pathlib import Path
from subset_utils import columns_joined, columns_tupled, quoter, schema_name, table_name, fully_qualified_table, redact_relationships
system_schemas_str = ','.join(['\'' + schema + '\'' for schema in ['information_schema', 'performance_schema', 'sys', 'mysql', 'innodb','tmp']])
temp_db = 'tonic_subset_temp_db_398dhjr23'
def prep_temp_dbs(source_conn, destination_conn):
run_query('DROP DATABASE IF EXISTS ' + temp_db, source_conn)
run_query('DROP DATABASE IF EXISTS ' + temp_db, destination_conn)
run_query('CREATE DATABASE IF NOT EXISTS ' + temp_db, source_conn)
run_query('CREATE DATABASE IF NOT EXISTS ' + temp_db, destination_conn)
def unprep_temp_dbs(source_conn, destination_conn):
run_query('DROP DATABASE IF EXISTS ' + temp_db, source_conn)
run_query('DROP DATABASE IF EXISTS ' + temp_db, destination_conn)
def turn_off_constraints(connection):
cur = connection.cursor()
try:
cur.execute('SET UNIQUE_CHECKS=0, FOREIGN_KEY_CHECKS=0;')
finally:
cur.close()
def copy_rows(source, destination, query, destination_table):
cursor = source.cursor()
try:
cursor.execute(query)
fetch_row_count = 1000
while True:
rows = cursor.fetchmany(fetch_row_count)
if len(rows) == 0:
break
template = ','.join(['%s']*len(rows[0]))
destination_cursor = destination.cursor()
insert_query = 'INSERT INTO {} VALUES ({})'.format(fully_qualified_table(destination_table), template)
destination_cursor.executemany(insert_query, rows)
destination_cursor.close()
destination.commit()
if len(rows) < fetch_row_count:
# necessary because mysql doesn't behave if you fetchmany after the last row
break
except Exception as e:
if hasattr(e, 'msg') and e.msg.startswith('Table') and e.msg.endswith('doesn\'t exist'):
raise ValueError('Your database has foreign keys to another database. This is not currently supported.')
else:
raise e
finally:
cursor.close()
def create_id_temp_table(conn, number_of_columns):
temp_table = temp_db + '.' + str(uuid.uuid4())
cursor = conn.cursor()
column_defs = ',\n'.join([' col' + str(aye) + ' text' for aye in range(number_of_columns)])
q = 'CREATE TABLE {} (\n {} \n)'.format(fully_qualified_table(temp_table), column_defs)
cursor.execute(q)
cursor.close()
return temp_table
def copy_to_temp_table(conn, query, target_table, pk_columns = None):
cur = conn.cursor()
temp_table = fully_qualified_table(source_db_temp_table(target_table))
try:
cur.execute('CREATE TABLE IF NOT EXISTS ' + temp_table + ' AS ' + query + ' LIMIT 0')
if pk_columns:
query = query + ' WHERE {} NOT IN (SELECT {} FROM {})'.format(columns_tupled(pk_columns), columns_joined(pk_columns), temp_table)
cur.execute('INSERT INTO ' + temp_table + ' ' + query)
conn.commit()
finally:
cur.close()
def clean_temp_table_cells(fk_table, fk_columns, target_table, target_columns, conn):
fk_alias = 'tonic_subset_398dhjr23_fk'
target_alias = 'tonic_subset_398dhjr23_target'
fk_table = fully_qualified_table(source_db_temp_table(fk_table))
target_table = fully_qualified_table(source_db_temp_table(target_table))
assignment_list = ','.join(['{}.{} = NULL'.format(fk_alias, quoter(c)) for c in fk_columns])
column_matching = ' AND '.join(['{}.{} = {}.{}'.format(fk_alias, quoter(fc), target_alias, quoter(tc)) for fc, tc in zip(fk_columns, target_columns)])
target_columns_null = ' AND '.join(['{}.{} IS NULL'.format(target_alias, quoter(tc)) for tc in target_columns]
+ ['{}.{} IS NOT NULL'.format(fk_alias, quoter(c)) for c in fk_columns])
q = 'UPDATE {} {} LEFT JOIN {} {} ON {} SET {} WHERE {}'.format(fk_table, fk_alias, target_table, target_alias, column_matching, assignment_list, target_columns_null)
run_query(q, conn)
def source_db_temp_table(target_table):
return temp_db + '.' + schema_name(target_table) + '_' + table_name(target_table)
def get_redacted_table_references(table_name, tables, conn):
relationships = get_unredacted_fk_relationships(tables, conn)
redacted = redact_relationships(relationships)
return [r for r in redacted if r['target_table']==table_name]
def get_unredacted_fk_relationships(tables, conn):
cur = conn.cursor()
q = '''
SELECT
concat(table_schema, '.', table_name) AS fk_table,
group_concat(column_name ORDER BY ordinal_position) AS fk_column,
concat(referenced_table_schema, '.', referenced_table_name) AS pk_name,
group_concat(referenced_column_name ORDER BY ordinal_position) AS pk_name
FROM
information_schema.key_column_usage
WHERE
referenced_table_schema NOT IN ({})
GROUP BY 1, 3, constraint_schema, constraint_name;
'''.format(system_schemas_str)
cur.execute(q)
relationships = list()
for row in cur.fetchall():
d = dict()
d['fk_table'] = row[0]
d['fk_columns'] = row[1].split(',')
d['target_table'] = row[2]
d['target_columns'] = row[3].split(',')
if d['fk_table'] in tables and d['target_table'] in tables:
relationships.append( d )
cur.close()
for augment in config_reader.get_fk_augmentation():
not_present = True
for r in relationships:
not_present = not_present and not all([r[key] == augment[key] for key in r.keys()])
if not not_present:
break
if augment['fk_table'] in tables and augment['target_table'] in tables and not_present:
relationships.append(augment)
return relationships
def run_query(query, conn, commit=True):
cur = conn.cursor()
try:
cur.execute(query)
if commit:
conn.commit()
finally:
cur.close()
def get_table_count_estimate(table_name, schema, conn):
cur = conn.cursor()
try:
cur.execute('SELECT table_rows AS count FROM information_schema.tables WHERE table_schema=\'{}\' AND table_name=\'{}\''.format(schema, table_name))
return cur.fetchone()[0]
finally:
cur.close()
def get_table_columns(table, schema, conn):
cur = conn.cursor()
try:
cur.execute('SELECT column_name FROM information_schema.columns WHERE table_schema = \'{}\' AND table_name = \'{}\' ORDER BY ordinal_position'.format(schema, table))
return [r[0] for r in cur.fetchall()]
finally:
cur.close()
def list_all_tables(db_connect):
conn = db_connect.get_db_connection()
cur = conn.cursor()
config_reader.get_source_db_connection_info()
try:
cur.execute('''SELECT
concat(concat(table_schema,'.'),table_name)
FROM
information_schema.tables
WHERE
table_schema = '{}' AND table_type = 'BASE TABLE';'''.format(db_connect.db_name))
return [r[0] for r in cur.fetchall()]
finally:
cur.close()
def truncate_table(target_table, conn):
cur = conn.cursor()
try:
cur.execute("TRUNCATE TABLE {}".format(target_table))
conn.commit()
finally:
cur.close()