293 lines
9.0 KiB
Python
293 lines
9.0 KiB
Python
import datetime
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import decimal
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import functools
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import logging
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import time
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from contextlib import contextmanager
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from django.db import NotSupportedError
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from django.utils.crypto import md5
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from django.utils.dateparse import parse_time
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logger = logging.getLogger("django.db.backends")
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class CursorWrapper:
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def __init__(self, cursor, db):
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self.cursor = cursor
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self.db = db
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WRAP_ERROR_ATTRS = frozenset(["fetchone", "fetchmany", "fetchall", "nextset"])
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def __getattr__(self, attr):
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cursor_attr = getattr(self.cursor, attr)
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if attr in CursorWrapper.WRAP_ERROR_ATTRS:
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return self.db.wrap_database_errors(cursor_attr)
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else:
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return cursor_attr
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def __iter__(self):
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with self.db.wrap_database_errors:
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yield from self.cursor
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def __enter__(self):
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return self
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def __exit__(self, type, value, traceback):
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# Close instead of passing through to avoid backend-specific behavior
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# (#17671). Catch errors liberally because errors in cleanup code
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# aren't useful.
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try:
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self.close()
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except self.db.Database.Error:
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pass
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# The following methods cannot be implemented in __getattr__, because the
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# code must run when the method is invoked, not just when it is accessed.
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def callproc(self, procname, params=None, kparams=None):
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# Keyword parameters for callproc aren't supported in PEP 249, but the
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# database driver may support them (e.g. cx_Oracle).
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if kparams is not None and not self.db.features.supports_callproc_kwargs:
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raise NotSupportedError(
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"Keyword parameters for callproc are not supported on this "
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"database backend."
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)
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self.db.validate_no_broken_transaction()
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with self.db.wrap_database_errors:
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if params is None and kparams is None:
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return self.cursor.callproc(procname)
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elif kparams is None:
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return self.cursor.callproc(procname, params)
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else:
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params = params or ()
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return self.cursor.callproc(procname, params, kparams)
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def execute(self, sql, params=None):
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return self._execute_with_wrappers(
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sql, params, many=False, executor=self._execute
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)
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def executemany(self, sql, param_list):
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return self._execute_with_wrappers(
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sql, param_list, many=True, executor=self._executemany
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)
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def _execute_with_wrappers(self, sql, params, many, executor):
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context = {"connection": self.db, "cursor": self}
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for wrapper in reversed(self.db.execute_wrappers):
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executor = functools.partial(wrapper, executor)
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return executor(sql, params, many, context)
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def _execute(self, sql, params, *ignored_wrapper_args):
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self.db.validate_no_broken_transaction()
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with self.db.wrap_database_errors:
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if params is None:
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# params default might be backend specific.
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return self.cursor.execute(sql)
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else:
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return self.cursor.execute(sql, params)
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def _executemany(self, sql, param_list, *ignored_wrapper_args):
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self.db.validate_no_broken_transaction()
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with self.db.wrap_database_errors:
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return self.cursor.executemany(sql, param_list)
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class CursorDebugWrapper(CursorWrapper):
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# XXX callproc isn't instrumented at this time.
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def execute(self, sql, params=None):
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with self.debug_sql(sql, params, use_last_executed_query=True):
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return super().execute(sql, params)
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def executemany(self, sql, param_list):
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with self.debug_sql(sql, param_list, many=True):
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return super().executemany(sql, param_list)
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@contextmanager
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def debug_sql(
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self, sql=None, params=None, use_last_executed_query=False, many=False
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):
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start = time.monotonic()
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try:
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yield
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finally:
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stop = time.monotonic()
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duration = stop - start
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if use_last_executed_query:
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sql = self.db.ops.last_executed_query(self.cursor, sql, params)
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try:
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times = len(params) if many else ""
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except TypeError:
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# params could be an iterator.
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times = "?"
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self.db.queries_log.append(
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{
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"sql": "%s times: %s" % (times, sql) if many else sql,
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"time": "%.3f" % duration,
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}
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)
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logger.debug(
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"(%.3f) %s; args=%s; alias=%s",
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duration,
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sql,
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params,
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self.db.alias,
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extra={
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"duration": duration,
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"sql": sql,
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"params": params,
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"alias": self.db.alias,
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},
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)
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def split_tzname_delta(tzname):
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"""
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Split a time zone name into a 3-tuple of (name, sign, offset).
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"""
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for sign in ["+", "-"]:
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if sign in tzname:
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name, offset = tzname.rsplit(sign, 1)
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if offset and parse_time(offset):
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return name, sign, offset
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return tzname, None, None
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###############################################
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# Converters from database (string) to Python #
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###############################################
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def typecast_date(s):
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return (
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datetime.date(*map(int, s.split("-"))) if s else None
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) # return None if s is null
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def typecast_time(s): # does NOT store time zone information
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if not s:
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return None
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hour, minutes, seconds = s.split(":")
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if "." in seconds: # check whether seconds have a fractional part
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seconds, microseconds = seconds.split(".")
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else:
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microseconds = "0"
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return datetime.time(
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int(hour), int(minutes), int(seconds), int((microseconds + "000000")[:6])
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)
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def typecast_timestamp(s): # does NOT store time zone information
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# "2005-07-29 15:48:00.590358-05"
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# "2005-07-29 09:56:00-05"
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if not s:
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return None
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if " " not in s:
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return typecast_date(s)
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d, t = s.split()
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# Remove timezone information.
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if "-" in t:
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t, _ = t.split("-", 1)
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elif "+" in t:
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t, _ = t.split("+", 1)
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dates = d.split("-")
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times = t.split(":")
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seconds = times[2]
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if "." in seconds: # check whether seconds have a fractional part
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seconds, microseconds = seconds.split(".")
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else:
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microseconds = "0"
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return datetime.datetime(
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int(dates[0]),
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int(dates[1]),
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int(dates[2]),
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int(times[0]),
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int(times[1]),
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int(seconds),
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int((microseconds + "000000")[:6]),
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)
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###############################################
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# Converters from Python to database (string) #
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###############################################
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def split_identifier(identifier):
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"""
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Split an SQL identifier into a two element tuple of (namespace, name).
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The identifier could be a table, column, or sequence name might be prefixed
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by a namespace.
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"""
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try:
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namespace, name = identifier.split('"."')
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except ValueError:
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namespace, name = "", identifier
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return namespace.strip('"'), name.strip('"')
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def truncate_name(identifier, length=None, hash_len=4):
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"""
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Shorten an SQL identifier to a repeatable mangled version with the given
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length.
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If a quote stripped name contains a namespace, e.g. USERNAME"."TABLE,
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truncate the table portion only.
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"""
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namespace, name = split_identifier(identifier)
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if length is None or len(name) <= length:
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return identifier
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digest = names_digest(name, length=hash_len)
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return "%s%s%s" % (
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'%s"."' % namespace if namespace else "",
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name[: length - hash_len],
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digest,
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)
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def names_digest(*args, length):
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"""
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Generate a 32-bit digest of a set of arguments that can be used to shorten
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identifying names.
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"""
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h = md5(usedforsecurity=False)
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for arg in args:
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h.update(arg.encode())
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return h.hexdigest()[:length]
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def format_number(value, max_digits, decimal_places):
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"""
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Format a number into a string with the requisite number of digits and
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decimal places.
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"""
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if value is None:
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return None
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context = decimal.getcontext().copy()
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if max_digits is not None:
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context.prec = max_digits
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if decimal_places is not None:
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value = value.quantize(
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decimal.Decimal(1).scaleb(-decimal_places), context=context
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)
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else:
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context.traps[decimal.Rounded] = 1
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value = context.create_decimal(value)
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return "{:f}".format(value)
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def strip_quotes(table_name):
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"""
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Strip quotes off of quoted table names to make them safe for use in index
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names, sequence names, etc. For example '"USER"."TABLE"' (an Oracle naming
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scheme) becomes 'USER"."TABLE'.
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"""
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has_quotes = table_name.startswith('"') and table_name.endswith('"')
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return table_name[1:-1] if has_quotes else table_name
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