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dbconnection.py
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dbconnection.py
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"""
dbconnection.py is part of Coquery.
Copyright (c) 2016 Gero Kunter (gero.kunter@coquery.org)
Copyright (c) 2016 Gero Kunter (gero.kunter@coquery.org)
Coquery is released under the terms of the GNU General Public License (v3).
For details, see the file LICENSE that you should have received along
with Coquery. If not, see <http://www.gnu.org/licenses/>.
"""
from __future__ import unicode_literals
from __future__ import print_function
try:
str = unicode
except NameError:
pass
import warnings
import copy
from collections import defaultdict
import sqlite3
import options
if options._use_mysql:
import pymysql
import pymysql.cursors
from defines import *
import logging
verbose = False
name = ""
logger = None
insert_cache = defaultdict(list)
class DBConnection(object):
def __init__(self, db_user="mysql", db_host="localhost", db_type="mysql", db_port=3306, db_pass="mysql", local_infile=0, encoding="utf8", db_path=""):
if db_type == SQL_MYSQL and not options._use_mysql:
raise DependencyError("pymysql")
self.db_type = db_type
self.db_host = db_host
self.db_port = db_port
self.db_user = db_user
self.db_passwd = db_pass
self.db_path = None
self.db_name = None
self._encoding = encoding
if db_type == SQL_MYSQL:
self._con = pymysql.connect(
host=db_host,
user=db_user,
passwd=db_pass,
port=db_port,
local_infile=local_infile,
charset=encoding)
self.set_variable("NAMES", encoding)
self.set_variable("CHARACTER SET", encoding)
self.set_variable("autocommit", 0)
self.set_variable("unique_checks", 0)
self.set_variable("foreign_key_checks", 0)
elif db_type == SQL_SQLITE:
self._con = None
else:
raise RuntimeError("Database type '{}' not supported.".format(db_type))
def Con(self):
if self.db_type == SQL_MYSQL:
return self._con
elif self.db_type == SQL_SQLITE:
if not self._con:
self._con = sqlite3.connect(self.db_path)
return self._con
@staticmethod
def sqlite_path(db_name):
return os.path.join(
options.get_home_dir(),
"databases",
options.cfg.current_server,
"{}.db".format(db_name))
def start_transaction(self):
if self.db_type == SQL_MYSQL:
cur = self.Con().cursor()
self.execute(cur, "START TRANSACTION")
def has_database(self, database_name):
if self.db_type == SQL_MYSQL:
cur = self.Con().cursor()
self.execute(cur, "SHOW DATABASES")
try:
for x in cur:
if x[0] == database_name.split()[0]:
return database_name
except pymysql.ProgrammingError as ex:
warning.warn(ex)
if cur:
warning.warn(cur.messages)
else:
warning.warn(self.Con().messages)
return False
elif self.db_type == SQL_SQLITE:
return os.path.exists(DBConnection.sqlite_path(database_name))
else:
raise Exception
def create_database(self, database_name):
if self.db_type == SQL_MYSQL:
cur = self.Con().cursor()
self.execute(cur, "CREATE DATABASE {} CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci".format(database_name.split()[0]))
elif self.db_type == SQL_SQLITE:
# SQLite databases are created when making a connection to them
pass
def use_database(self, database_name):
if self.db_type == SQL_MYSQL:
cur = self.Con().cursor()
self.execute(cur, "USE {}".format(database_name.split()[0]))
elif self.db_type == SQL_SQLITE:
self.db_path = DBConnection.sqlite_path(database_name)
def drop_database(self, database_name):
if self.db_type == SQL_MYSQL:
cur = self.Con().cursor()
self.execute(cur, "DROP DATABASE {}".format(database_name.split()[0]))
elif self.db_type == SQL_SQLITE:
os.remove(DBConnection.sqlite_path(database_name))
def load_infile(self, file_name, table_name, arguments):
cur = self.Con().cursor()
self.execute(cur, "LOAD DATA LOCAL INFILE '{}' INTO TABLE {} {}".format(file_name, table_name, arguments))
def executemany(self, s, d):
cur = self.Con().cursor()
if self.db_type == SQL_SQLITE:
s = s.replace("%s", "?")
cur.executemany(s, d)
def execute(self, cursor, command, override=False):
if verbose:
logger.info(command)
try:
return cursor.execute(command)
except Exception as e:
print(e)
warnings.warn("An error occurred when executing MySQL command '{}'.".format(command))
raise e
def has_table(self, table_name):
cur = self.Con().cursor()
if self.db_type == SQL_MYSQL:
return self.execute(cur, "SELECT * FROM information_schema.tables WHERE table_schema = '{}' AND table_name = '{}'".format(self.db_name, table_name), override=True)
elif self.db_type == SQL_SQLITE:
S = "SELECT * from sqlite_master WHERE type = 'table' and name = '{}'".format(table_name)
return self.execute(cur, S).fetchall()
def load_data(self, table_name, path, arguments=""):
cur = self.Con().cursor()
return self.execute(cur, "LOAD DATA LOCAL INFILE '{}' INTO TABLE {} {}".format(path, table_name, arguments))
def create_table(self, table_name, description, override=False):
cur = self.Con().cursor()
return self.execute(cur, 'CREATE TABLE {} ({})'.format(table_name, description), override=override)
def drop_table(self, table_name):
cur = self.Con().cursor()
return self.execute(cur, 'DROP TABLE {}'.format(table_name))
def has_index(self, table_name, index_name):
cur = self.Con().cursor()
if self.db_type == SQL_MYSQL:
return self.execute(cur, 'SHOW INDEX FROM %s WHERE Key_name = "%s"' % (table_name, index_name), override=True)
elif self.db_type == SQL_SQLITE:
results = self.execute(cur, "SELECT name FROM sqlite_master WHERE type = 'index' AND name = '{}' AND tbl_name = '{}'".format(index_name, table_name))
return len(results.fetchall())
def get_index_length(self, table_name, column_name, coverage=0.95):
"""
Return the index length that is required for the given coverage.
If the current SQL engine is SQL_SQLITE, this method always returns
None.
Parameters
----------
table_name : string
The name of the table
column_name : string
The name of the column for which an index is to be created
coverage : float
The coverage percentage that the index should cover. Default: 0.95
Returns
-------
number : int
The first character length that reaches the given coverage, or
None if the coverage cannot be reached.
"""
if self.db_type == SQL_SQLITE:
return None
S = """
SELECT len,
COUNT(DISTINCT SUBSTR({column}, 1, len)) AS number,
total,
ROUND(COUNT(DISTINCT SUBSTR({column}, 1, len)) / total, 2) AS coverage
FROM {table}
INNER JOIN (
SELECT COUNT(DISTINCT {column}) total
FROM {table}
WHERE {column} != "") count_total
INNER JOIN (
SELECT @x := @x + 1 AS len
FROM {table}, (SELECT @x := 0) count_init
LIMIT 32) count_inc
GROUP BY len""".format(
table=table_name, column=column_name)
cur = self.Con().cursor()
self.execute(cur, S)
max_c = None
for x in cur.fetchall():
if not max_c or x[3] > max_c[3]:
max_c = x
if x[3] >= coverage:
print("{}.{}: index length {}".format(table_name, column_name, x[0]))
logger.info("{}.{}: index length {}".format(table_name, column_name, x[0]))
return int(x[0])
if max_c:
print("{}.{}: index length {}".format(table_name, column_name, max_c[0]))
logger.info("{}.{}: index length {}".format(table_name, column_name, max_c[0]))
return int(max_c[0])
return None
def create_index(self, table_name, index_name, variables, index_type=None, index_length=None):
cur = self.Con().cursor()
# Do not create an index if the table is empty:
self.execute(cur, "SELECT * FROM {} LIMIT 1".format(table_name))
if not cur.fetchone():
return
if index_length:
variables = ["%s(%s)" % (variables[0], index_length)]
if index_type:
S = 'CREATE INDEX {} ON {}({}) USING {}'.format(
index_name, table_name, ",".join(variables), index_type)
else:
S = 'CREATE INDEX {} ON {}({})'.format(
index_name, table_name, ",".join(variables))
self.execute(cur, S)
def get_field_type(self, table_name, column_name):
cur = self.Con().cursor()
if self.db_type == SQL_MYSQL:
S = "SHOW FIELDS FROM %s WHERE Field = '%s'" % (table_name, column_name)
self.execute(cur, S, override=True)
Results = cur.fetchone()
try:
if isinstance(Results, bytes):
Results = Results.decode("utf-8")
except NameError:
Results = str(Results)
if Results:
field_type = Results[1]
if Results[2] == "NO":
field_type += " NOT NULL"
return str(field_type)
else:
return None
elif self.db_type == SQL_SQLITE:
S = "PRAGMA table_info({})".format(table_name)
self.execute(cur, S)
for row in cur.fetchall():
result = dict(zip("cid", "name", "type", "notnull", "dflt_value", "pk"),
row)
column = result["name"]
data_type = result["type"]
not_null = result["notnull"]
if column == column_name:
if not_null:
return "{} NOT NULL".format(data_type)
else:
return str(data_type)
def get_optimal_field_type(self, table_name, column_name):
if self.db_type == SQL_SQLITE:
return self.get_field_type(table_name, column_name)
cur = self.Con().cursor()
self.execute(cur, "SELECT %s FROM %s PROCEDURE ANALYSE()" % (column_name, table_name), override=True)
x = cur.fetchone()[-1]
try:
if isinstance(x, bytes):
x = x.decode("utf-8")
except NameError:
x = str(x)
return x
def modify_field_type(self, table_name, column_name, new_type):
cur = self.Con().cursor()
old_field = self.get_field_type(table_name, column_name)
self.execute(cur, "ALTER TABLE %s MODIFY %s %s" % (table_name, column_name, new_type))
def read_table(self, table_name, FUN):
cur = self.Con().cursor(MySQLdb.cursors.SSCursor)
self.execute(cur, "SELECT * FROM %s" % table_name, override=True)
D = {}
for current_entry in cur.fetchall():
try:
x = FUN(current_entry)
except UnicodeDecodeError as e:
x = FUN([str(x).decode("utf-8") for x in current_entry])
D[x] = current_entry
return D
def get_max(self, table_name, column_name):
cur = self.Con().cursor()
self.execute(cur, 'SELECT MAX(%s) FROM %s' % (column_name, table_name), override=True)
try:
return int(max(0, cur.fetchall() [0] [0]))
except (TypeError, ValueError):
return None
def get_number_of_rows(self, table_name):
cur = self.Con().cursor()
self.execute(cur, 'SELECT COUNT(*) FROM %s' % (table_name), override=True)
try:
return int(max(0, cur.fetchall() [0] [0]))
except TypeError:
return None
def find(self, table_name, values, additional_variables=[], case=False):
""" Obtain all records from table_name that match the column-value
pairs given in the dict values."""
if self.db_type == SQL_MYSQL:
cur = self.Con().cursor(pymysql.cursors.DictCursor)
elif self.db_type == SQL_SQLITE:
con = self.Con()
con.row_factory = sqlite3.Row
cur = con.cursor()
variables = list(values.keys()) + additional_variables
where = []
for column, value in values.items():
where.append('{} = "{}"'.format(column, str(value).replace('"', '""')))
if case:
S = "SELECT {} FROM {} WHERE BINARY {}".format(", ".join(variables), table_name, " AND BINARY ".join(where))
else:
S = "SELECT {} FROM {} WHERE {}".format(", ".join(variables), table_name, " AND ".join(where))
S = S.replace("\\", "\\\\")
try:
self.execute(cur, S, override=True)
except Exception as e:
print(e)
raise e
return cur.fetchall()
def insert(self, table_name, data):
cur = self.Con().cursor()
# take care of quote characters and backslashes:
new_data = copy.copy(data)
for x in new_data:
new_data[x] = "%s" % str(new_data[x]).replace('"', '""')
new_data[x] = new_data[x].replace("\\", "\\\\")
S = "INSERT INTO {}({}) VALUES({})".format(
table_name,
",".join(new_data.keys()),
",".join('"%s"' % x for x in new_data.values()))
self.execute(cur, S)
return self.Con().insert_id()
def insert_id(self):
return self.Con().insert_id()
def set_variable(self, variable, value):
if self.db_type == SQL_MYSQL:
cur = self.Con().cursor()
if isinstance(value, str):
self.execute(cur, "SET {} '{}'".format(variable, value), override=True)
else:
self.execute(cur, "SET {}={}".format(variable, value), override=True)
def commit(self):
self.Con().commit()
def close(self):
self.Con().commit()
self.Con().close()