220 lines
8.9 KiB
Python
220 lines
8.9 KiB
Python
from collections import namedtuple
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from MySQLdb.constants import FIELD_TYPE
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from django.db.backends.base.introspection import (
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BaseDatabaseIntrospection, FieldInfo, TableInfo,
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)
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from django.utils.datastructures import OrderedSet
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from django.utils.encoding import force_text
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FieldInfo = namedtuple('FieldInfo', FieldInfo._fields + ('extra', 'default'))
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InfoLine = namedtuple('InfoLine', 'col_name data_type max_len num_prec num_scale extra column_default')
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class DatabaseIntrospection(BaseDatabaseIntrospection):
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data_types_reverse = {
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FIELD_TYPE.BLOB: 'TextField',
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FIELD_TYPE.CHAR: 'CharField',
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FIELD_TYPE.DECIMAL: 'DecimalField',
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FIELD_TYPE.NEWDECIMAL: 'DecimalField',
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FIELD_TYPE.DATE: 'DateField',
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FIELD_TYPE.DATETIME: 'DateTimeField',
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FIELD_TYPE.DOUBLE: 'FloatField',
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FIELD_TYPE.FLOAT: 'FloatField',
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FIELD_TYPE.INT24: 'IntegerField',
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FIELD_TYPE.LONG: 'IntegerField',
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FIELD_TYPE.LONGLONG: 'BigIntegerField',
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FIELD_TYPE.SHORT: 'SmallIntegerField',
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FIELD_TYPE.STRING: 'CharField',
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FIELD_TYPE.TIME: 'TimeField',
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FIELD_TYPE.TIMESTAMP: 'DateTimeField',
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FIELD_TYPE.TINY: 'IntegerField',
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FIELD_TYPE.TINY_BLOB: 'TextField',
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FIELD_TYPE.MEDIUM_BLOB: 'TextField',
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FIELD_TYPE.LONG_BLOB: 'TextField',
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FIELD_TYPE.VAR_STRING: 'CharField',
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}
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def get_field_type(self, data_type, description):
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field_type = super(DatabaseIntrospection, self).get_field_type(data_type, description)
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if 'auto_increment' in description.extra:
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if field_type == 'IntegerField':
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return 'AutoField'
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elif field_type == 'BigIntegerField':
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return 'BigAutoField'
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return field_type
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def get_table_list(self, cursor):
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"""
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Returns a list of table and view names in the current database.
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"""
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cursor.execute("SHOW FULL TABLES")
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return [TableInfo(row[0], {'BASE TABLE': 't', 'VIEW': 'v'}.get(row[1]))
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for row in cursor.fetchall()]
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def get_table_description(self, cursor, table_name):
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"""
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Returns a description of the table, with the DB-API cursor.description interface."
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"""
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# information_schema database gives more accurate results for some figures:
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# - varchar length returned by cursor.description is an internal length,
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# not visible length (#5725)
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# - precision and scale (for decimal fields) (#5014)
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# - auto_increment is not available in cursor.description
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cursor.execute("""
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SELECT column_name, data_type, character_maximum_length, numeric_precision,
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numeric_scale, extra, column_default
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FROM information_schema.columns
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WHERE table_name = %s AND table_schema = DATABASE()""", [table_name])
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field_info = {line[0]: InfoLine(*line) for line in cursor.fetchall()}
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cursor.execute("SELECT * FROM %s LIMIT 1" % self.connection.ops.quote_name(table_name))
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def to_int(i):
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return int(i) if i is not None else i
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fields = []
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for line in cursor.description:
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col_name = force_text(line[0])
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fields.append(
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FieldInfo(*(
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(col_name,) +
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line[1:3] +
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(
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to_int(field_info[col_name].max_len) or line[3],
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to_int(field_info[col_name].num_prec) or line[4],
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to_int(field_info[col_name].num_scale) or line[5],
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line[6],
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field_info[col_name].extra,
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field_info[col_name].column_default,
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)
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))
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)
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return fields
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def get_relations(self, cursor, table_name):
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"""
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Returns a dictionary of {field_name: (field_name_other_table, other_table)}
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representing all relationships to the given table.
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"""
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constraints = self.get_key_columns(cursor, table_name)
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relations = {}
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for my_fieldname, other_table, other_field in constraints:
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relations[my_fieldname] = (other_field, other_table)
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return relations
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def get_key_columns(self, cursor, table_name):
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"""
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Returns a list of (column_name, referenced_table_name, referenced_column_name) for all
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key columns in given table.
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"""
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key_columns = []
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cursor.execute("""
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SELECT column_name, referenced_table_name, referenced_column_name
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FROM information_schema.key_column_usage
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WHERE table_name = %s
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AND table_schema = DATABASE()
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AND referenced_table_name IS NOT NULL
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AND referenced_column_name IS NOT NULL""", [table_name])
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key_columns.extend(cursor.fetchall())
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return key_columns
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def get_indexes(self, cursor, table_name):
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cursor.execute("SHOW INDEX FROM %s" % self.connection.ops.quote_name(table_name))
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# Do a two-pass search for indexes: on first pass check which indexes
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# are multicolumn, on second pass check which single-column indexes
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# are present.
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rows = list(cursor.fetchall())
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multicol_indexes = set()
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for row in rows:
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if row[3] > 1:
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multicol_indexes.add(row[2])
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indexes = {}
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for row in rows:
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if row[2] in multicol_indexes:
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continue
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if row[4] not in indexes:
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indexes[row[4]] = {'primary_key': False, 'unique': False}
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# It's possible to have the unique and PK constraints in separate indexes.
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if row[2] == 'PRIMARY':
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indexes[row[4]]['primary_key'] = True
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if not row[1]:
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indexes[row[4]]['unique'] = True
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return indexes
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def get_storage_engine(self, cursor, table_name):
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"""
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Retrieves the storage engine for a given table. Returns the default
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storage engine if the table doesn't exist.
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"""
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cursor.execute(
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"SELECT engine "
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"FROM information_schema.tables "
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"WHERE table_name = %s", [table_name])
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result = cursor.fetchone()
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if not result:
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return self.connection.features._mysql_storage_engine
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return result[0]
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def get_constraints(self, cursor, table_name):
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"""
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Retrieves any constraints or keys (unique, pk, fk, check, index) across one or more columns.
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"""
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constraints = {}
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# Get the actual constraint names and columns
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name_query = """
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SELECT kc.`constraint_name`, kc.`column_name`,
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kc.`referenced_table_name`, kc.`referenced_column_name`
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FROM information_schema.key_column_usage AS kc
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WHERE
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kc.table_schema = DATABASE() AND
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kc.table_name = %s
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"""
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cursor.execute(name_query, [table_name])
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for constraint, column, ref_table, ref_column in cursor.fetchall():
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if constraint not in constraints:
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constraints[constraint] = {
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'columns': OrderedSet(),
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'primary_key': False,
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'unique': False,
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'index': False,
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'check': False,
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'foreign_key': (ref_table, ref_column) if ref_column else None,
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}
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constraints[constraint]['columns'].add(column)
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# Now get the constraint types
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type_query = """
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SELECT c.constraint_name, c.constraint_type
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FROM information_schema.table_constraints AS c
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WHERE
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c.table_schema = DATABASE() AND
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c.table_name = %s
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"""
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cursor.execute(type_query, [table_name])
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for constraint, kind in cursor.fetchall():
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if kind.lower() == "primary key":
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constraints[constraint]['primary_key'] = True
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constraints[constraint]['unique'] = True
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elif kind.lower() == "unique":
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constraints[constraint]['unique'] = True
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# Now add in the indexes
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cursor.execute("SHOW INDEX FROM %s" % self.connection.ops.quote_name(table_name))
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for table, non_unique, index, colseq, column in [x[:5] for x in cursor.fetchall()]:
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if index not in constraints:
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constraints[index] = {
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'columns': OrderedSet(),
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'primary_key': False,
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'unique': False,
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'index': True,
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'check': False,
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'foreign_key': None,
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}
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constraints[index]['index'] = True
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constraints[index]['columns'].add(column)
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# Convert the sorted sets to lists
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for constraint in constraints.values():
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constraint['columns'] = list(constraint['columns'])
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return constraints
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