253 lines
10 KiB
Python
253 lines
10 KiB
Python
from collections import namedtuple
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import cx_Oracle
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from django.db import models
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from django.db.backends.base.introspection import (
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BaseDatabaseIntrospection, FieldInfo as BaseFieldInfo, TableInfo,
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)
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FieldInfo = namedtuple('FieldInfo', BaseFieldInfo._fields + ('is_autofield',))
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class DatabaseIntrospection(BaseDatabaseIntrospection):
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# Maps type objects to Django Field types.
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data_types_reverse = {
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cx_Oracle.BLOB: 'BinaryField',
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cx_Oracle.CLOB: 'TextField',
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cx_Oracle.DATETIME: 'DateField',
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cx_Oracle.FIXED_CHAR: 'CharField',
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cx_Oracle.FIXED_NCHAR: 'CharField',
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cx_Oracle.NATIVE_FLOAT: 'FloatField',
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cx_Oracle.NCHAR: 'CharField',
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cx_Oracle.NCLOB: 'TextField',
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cx_Oracle.NUMBER: 'DecimalField',
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cx_Oracle.STRING: 'CharField',
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cx_Oracle.TIMESTAMP: 'DateTimeField',
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}
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cache_bust_counter = 1
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def get_field_type(self, data_type, description):
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if data_type == cx_Oracle.NUMBER:
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precision, scale = description[4:6]
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if scale == 0:
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if precision > 11:
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return 'BigAutoField' if description.is_autofield else 'BigIntegerField'
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elif precision == 1:
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return 'BooleanField'
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elif description.is_autofield:
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return 'AutoField'
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else:
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return 'IntegerField'
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elif scale == -127:
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return 'FloatField'
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return super().get_field_type(data_type, description)
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def get_table_list(self, cursor):
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"""Return a list of table and view names in the current database."""
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cursor.execute("SELECT TABLE_NAME, 't' FROM USER_TABLES UNION ALL "
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"SELECT VIEW_NAME, 'v' FROM USER_VIEWS")
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return [TableInfo(row[0].lower(), row[1]) 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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Return a description of the table with the DB-API cursor.description
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interface.
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"""
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# user_tab_columns gives data default for columns
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cursor.execute("""
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SELECT
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column_name,
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data_default,
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CASE
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WHEN char_used IS NULL THEN data_length
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ELSE char_length
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END as internal_size,
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CASE
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WHEN identity_column = 'YES' THEN 1
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ELSE 0
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END as is_autofield
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FROM user_tab_cols
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WHERE table_name = UPPER(%s)""", [table_name])
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field_map = {
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column: (internal_size, default if default != 'NULL' else None, is_autofield)
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for column, default, internal_size, is_autofield in cursor.fetchall()
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}
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self.cache_bust_counter += 1
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cursor.execute("SELECT * FROM {} WHERE ROWNUM < 2 AND {} > 0".format(
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self.connection.ops.quote_name(table_name),
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self.cache_bust_counter))
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description = []
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for desc in cursor.description:
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name = desc[0]
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internal_size, default, is_autofield = field_map[name]
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name = name % {} # cx_Oracle, for some reason, doubles percent signs.
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description.append(FieldInfo(
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name.lower(), *desc[1:3], internal_size, desc[4] or 0,
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desc[5] or 0, *desc[6:], default, is_autofield,
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))
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return description
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def table_name_converter(self, name):
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"""Table name comparison is case insensitive under Oracle."""
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return name.lower()
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def get_sequences(self, cursor, table_name, table_fields=()):
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cursor.execute("""
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SELECT
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user_tab_identity_cols.sequence_name,
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user_tab_identity_cols.column_name
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FROM
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user_tab_identity_cols,
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user_constraints,
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user_cons_columns cols
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WHERE
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user_constraints.constraint_name = cols.constraint_name
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AND user_constraints.table_name = user_tab_identity_cols.table_name
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AND cols.column_name = user_tab_identity_cols.column_name
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AND user_constraints.constraint_type = 'P'
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AND user_tab_identity_cols.table_name = UPPER(%s)
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""", [table_name])
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# Oracle allows only one identity column per table.
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row = cursor.fetchone()
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if row:
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return [{'name': row[0].lower(), 'table': table_name, 'column': row[1].lower()}]
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# To keep backward compatibility for AutoFields that aren't Oracle
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# identity columns.
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for f in table_fields:
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if isinstance(f, models.AutoField):
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return [{'table': table_name, 'column': f.column}]
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return []
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def get_relations(self, cursor, table_name):
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"""
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Return 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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table_name = table_name.upper()
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cursor.execute("""
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SELECT ca.column_name, cb.table_name, cb.column_name
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FROM user_constraints, USER_CONS_COLUMNS ca, USER_CONS_COLUMNS cb
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WHERE user_constraints.table_name = %s AND
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user_constraints.constraint_name = ca.constraint_name AND
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user_constraints.r_constraint_name = cb.constraint_name AND
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ca.position = cb.position""", [table_name])
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relations = {}
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for row in cursor.fetchall():
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relations[row[0].lower()] = (row[2].lower(), row[1].lower())
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return relations
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def get_key_columns(self, cursor, table_name):
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cursor.execute("""
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SELECT ccol.column_name, rcol.table_name AS referenced_table, rcol.column_name AS referenced_column
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FROM user_constraints c
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JOIN user_cons_columns ccol
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ON ccol.constraint_name = c.constraint_name
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JOIN user_cons_columns rcol
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ON rcol.constraint_name = c.r_constraint_name
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WHERE c.table_name = %s AND c.constraint_type = 'R'""", [table_name.upper()])
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return [tuple(cell.lower() for cell in row)
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for row in cursor.fetchall()]
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def get_constraints(self, cursor, table_name):
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"""
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Retrieve any constraints or keys (unique, pk, fk, check, index) across
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one or more columns.
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"""
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constraints = {}
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# Loop over the constraints, getting PKs, uniques, and checks
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cursor.execute("""
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SELECT
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user_constraints.constraint_name,
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LISTAGG(LOWER(cols.column_name), ',') WITHIN GROUP (ORDER BY cols.position),
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CASE user_constraints.constraint_type
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WHEN 'P' THEN 1
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ELSE 0
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END AS is_primary_key,
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CASE
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WHEN user_constraints.constraint_type IN ('P', 'U') THEN 1
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ELSE 0
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END AS is_unique,
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CASE user_constraints.constraint_type
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WHEN 'C' THEN 1
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ELSE 0
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END AS is_check_constraint
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FROM
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user_constraints
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LEFT OUTER JOIN
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user_cons_columns cols ON user_constraints.constraint_name = cols.constraint_name
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WHERE
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user_constraints.constraint_type = ANY('P', 'U', 'C')
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AND user_constraints.table_name = UPPER(%s)
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GROUP BY user_constraints.constraint_name, user_constraints.constraint_type
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""", [table_name])
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for constraint, columns, pk, unique, check in cursor.fetchall():
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constraints[constraint] = {
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'columns': columns.split(','),
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'primary_key': pk,
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'unique': unique,
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'foreign_key': None,
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'check': check,
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'index': unique, # All uniques come with an index
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}
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# Foreign key constraints
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cursor.execute("""
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SELECT
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cons.constraint_name,
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LISTAGG(LOWER(cols.column_name), ',') WITHIN GROUP (ORDER BY cols.position),
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LOWER(rcols.table_name),
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LOWER(rcols.column_name)
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FROM
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user_constraints cons
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INNER JOIN
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user_cons_columns rcols ON rcols.constraint_name = cons.r_constraint_name AND rcols.position = 1
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LEFT OUTER JOIN
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user_cons_columns cols ON cons.constraint_name = cols.constraint_name
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WHERE
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cons.constraint_type = 'R' AND
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cons.table_name = UPPER(%s)
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GROUP BY cons.constraint_name, rcols.table_name, rcols.column_name
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""", [table_name])
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for constraint, columns, other_table, other_column in cursor.fetchall():
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constraints[constraint] = {
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'primary_key': False,
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'unique': False,
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'foreign_key': (other_table, other_column),
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'check': False,
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'index': False,
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'columns': columns.split(','),
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}
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# Now get indexes
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cursor.execute("""
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SELECT
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ind.index_name,
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LOWER(ind.index_type),
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LISTAGG(LOWER(cols.column_name), ',') WITHIN GROUP (ORDER BY cols.column_position),
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LISTAGG(cols.descend, ',') WITHIN GROUP (ORDER BY cols.column_position)
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FROM
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user_ind_columns cols, user_indexes ind
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WHERE
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cols.table_name = UPPER(%s) AND
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NOT EXISTS (
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SELECT 1
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FROM user_constraints cons
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WHERE ind.index_name = cons.index_name
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) AND cols.index_name = ind.index_name
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GROUP BY ind.index_name, ind.index_type
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""", [table_name])
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for constraint, type_, columns, orders in cursor.fetchall():
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constraints[constraint] = {
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'primary_key': False,
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'unique': False,
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'foreign_key': None,
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'check': False,
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'index': True,
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'type': 'idx' if type_ == 'normal' else type_,
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'columns': columns.split(','),
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'orders': orders.split(','),
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}
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return constraints
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