def create_index(self, columns, name=None, **kw):
"""Create an index to speed up queries on a table.
If no ``name`` is given a random name is created.
::
table.create_index(['name', 'country'])
"""
columns = [self._get_column_name(c) for c in ensure_list(columns)]
with self.db.lock:
if not self.exists:
raise DatasetException("Table has not been created yet.")
for column in columns:
if not self.has_column(column):
return
if not self.has_index(columns):
self._threading_warn()
name = name or index_name(self.name, columns)
columns = [self.table.c[c] for c in columns]
# MySQL crashes out if you try to index very long text fields,
# apparently. This defines (a somewhat random) prefix that
# will be captured by the index, after which I assume the engine
# conducts a more linear scan:
mysql_length = {}
for col in columns:
if isinstance(col.type, MYSQL_LENGTH_TYPES):
mysql_length[col.name] = 10
kw["mysql_length"] = mysql_length
idx = Index(name, *columns, **kw)
idx.create(self.db.executable)
def create_index(self, columns, name=None, **kw):
"""Create an index to speed up queries on a table.
If no ``name`` is given a random name is created.
::
table.create_index(['name', 'country'])
"""
columns = [normalize_column_name(c) for c in ensure_tuple(columns)]
with self.db.lock:
if not self.exists:
raise DatasetException("Table has not been created yet.")
if not self.has_index(columns):
self._threading_warn()
name = name or index_name(self.name, columns)
columns = [self.table.c[c] for c in columns]
idx = Index(name, *columns, **kw)
idx.create(self.db.executable)
