330 lines
11 KiB
Python
330 lines
11 KiB
Python
import json
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import warnings
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import six
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from cqlengine import SizeTieredCompactionStrategy, LeveledCompactionStrategy
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from cqlengine import ONE
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from cqlengine.named import NamedTable
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from cqlengine.connection import execute, get_cluster
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from cqlengine.exceptions import CQLEngineException
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import logging
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from collections import namedtuple
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Field = namedtuple('Field', ['name', 'type'])
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logger = logging.getLogger(__name__)
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from cqlengine.models import Model
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# system keyspaces
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schema_columnfamilies = NamedTable('system', 'schema_columnfamilies')
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def create_keyspace(name, strategy_class='SimpleStrategy', replication_factor=3, durable_writes=True, **replication_values):
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"""
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creates a keyspace
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:param name: name of keyspace to create
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:param strategy_class: keyspace replication strategy class
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:param replication_factor: keyspace replication factor
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:param durable_writes: 1.2 only, write log is bypassed if set to False
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:param **replication_values: 1.2 only, additional values to ad to the replication data map
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"""
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cluster = get_cluster()
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if name not in cluster.metadata.keyspaces:
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#try the 1.2 method
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replication_map = {
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'class': strategy_class,
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'replication_factor':replication_factor
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}
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replication_map.update(replication_values)
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if strategy_class.lower() != 'simplestrategy':
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# Although the Cassandra documentation states for `replication_factor`
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# that it is "Required if class is SimpleStrategy; otherwise,
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# not used." we get an error if it is present.
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replication_map.pop('replication_factor', None)
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query = """
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CREATE KEYSPACE {}
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WITH REPLICATION = {}
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""".format(name, json.dumps(replication_map).replace('"', "'"))
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if strategy_class != 'SimpleStrategy':
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query += " AND DURABLE_WRITES = {}".format('true' if durable_writes else 'false')
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execute(query)
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def delete_keyspace(name):
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cluster = get_cluster()
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if name in cluster.metadata.keyspaces:
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execute("DROP KEYSPACE {}".format(name))
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def create_table(model, create_missing_keyspace=True):
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raise CQLEngineException("create_table is deprecated, please use sync_table")
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def sync_table(model, create_missing_keyspace=True):
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"""
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Inspects the model and creates / updates the corresponding table and columns.
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Note that the attributes removed from the model are not deleted on the database.
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They become effectively ignored by (will not show up on) the model.
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:param create_missing_keyspace: (Defaults to True) Flags to us that we need to create missing keyspace
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mentioned in the model automatically.
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:type create_missing_keyspace: bool
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"""
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if not issubclass(model, Model):
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raise CQLEngineException("Models must be derived from base Model.")
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if model.__abstract__:
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raise CQLEngineException("cannot create table from abstract model")
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#construct query string
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cf_name = model.column_family_name()
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raw_cf_name = model.column_family_name(include_keyspace=False)
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ks_name = model._get_keyspace()
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#create missing keyspace
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if create_missing_keyspace:
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create_keyspace(ks_name)
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cluster = get_cluster()
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keyspace = cluster.metadata.keyspaces[ks_name]
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tables = keyspace.tables
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#check for an existing column family
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if raw_cf_name not in tables:
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qs = get_create_table(model)
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try:
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execute(qs)
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except CQLEngineException as ex:
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# 1.2 doesn't return cf names, so we have to examine the exception
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# and ignore if it says the column family already exists
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if "Cannot add already existing column family" not in unicode(ex):
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raise
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else:
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# see if we're missing any columns
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fields = get_fields(model)
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field_names = [x.name for x in fields]
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for name, col in model._columns.items():
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if col.primary_key or col.partition_key: continue # we can't mess with the PK
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if col.db_field_name in field_names: continue # skip columns already defined
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# add missing column using the column def
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query = "ALTER TABLE {} add {}".format(cf_name, col.get_column_def())
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logger.debug(query)
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execute(query)
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update_compaction(model)
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table = cluster.metadata.keyspaces[ks_name].tables[raw_cf_name]
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indexes = [c for n,c in model._columns.items() if c.index]
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for column in indexes:
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if table.columns[column.db_field_name].index:
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continue
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qs = ['CREATE INDEX index_{}_{}'.format(raw_cf_name, column.db_field_name)]
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qs += ['ON {}'.format(cf_name)]
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qs += ['("{}")'.format(column.db_field_name)]
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qs = ' '.join(qs)
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execute(qs)
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def get_create_table(model):
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cf_name = model.column_family_name()
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qs = ['CREATE TABLE {}'.format(cf_name)]
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#add column types
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pkeys = [] # primary keys
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ckeys = [] # clustering keys
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qtypes = [] # field types
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def add_column(col):
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s = col.get_column_def()
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if col.primary_key:
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keys = (pkeys if col.partition_key else ckeys)
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keys.append('"{}"'.format(col.db_field_name))
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qtypes.append(s)
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for name, col in model._columns.items():
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add_column(col)
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qtypes.append('PRIMARY KEY (({}){})'.format(', '.join(pkeys), ckeys and ', ' + ', '.join(ckeys) or ''))
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qs += ['({})'.format(', '.join(qtypes))]
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with_qs = []
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table_properties = ['bloom_filter_fp_chance', 'caching', 'comment',
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'dclocal_read_repair_chance', 'default_time_to_live', 'gc_grace_seconds',
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'index_interval', 'memtable_flush_period_in_ms', 'populate_io_cache_on_flush',
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'read_repair_chance', 'replicate_on_write']
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for prop_name in table_properties:
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prop_value = getattr(model, '__{}__'.format(prop_name), None)
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if prop_value is not None:
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# Strings needs to be single quoted
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if isinstance(prop_value, six.string_types):
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prop_value = "'{}'".format(prop_value)
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with_qs.append("{} = {}".format(prop_name, prop_value))
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_order = ['"{}" {}'.format(c.db_field_name, c.clustering_order or 'ASC') for c in model._clustering_keys.values()]
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if _order:
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with_qs.append('clustering order by ({})'.format(', '.join(_order)))
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compaction_options = get_compaction_options(model)
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if compaction_options:
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compaction_options = json.dumps(compaction_options).replace('"', "'")
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with_qs.append("compaction = {}".format(compaction_options))
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# Add table properties.
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if with_qs:
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qs += ['WITH {}'.format(' AND '.join(with_qs))]
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qs = ' '.join(qs)
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return qs
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def get_compaction_options(model):
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"""
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Generates dictionary (later converted to a string) for creating and altering
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tables with compaction strategy
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:param model:
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:return:
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"""
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if not model.__compaction__:
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return {}
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result = {'class':model.__compaction__}
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def setter(key, limited_to_strategy = None):
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"""
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sets key in result, checking if the key is limited to either SizeTiered or Leveled
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:param key: one of the compaction options, like "bucket_high"
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:param limited_to_strategy: SizeTieredCompactionStrategy, LeveledCompactionStrategy
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:return:
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"""
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mkey = "__compaction_{}__".format(key)
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tmp = getattr(model, mkey)
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if tmp and limited_to_strategy and limited_to_strategy != model.__compaction__:
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raise CQLEngineException("{} is limited to {}".format(key, limited_to_strategy))
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if tmp:
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# Explicitly cast the values to strings to be able to compare the
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# values against introspected values from Cassandra.
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result[key] = str(tmp)
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setter('tombstone_compaction_interval')
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setter('tombstone_threshold')
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setter('bucket_high', SizeTieredCompactionStrategy)
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setter('bucket_low', SizeTieredCompactionStrategy)
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setter('max_threshold', SizeTieredCompactionStrategy)
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setter('min_threshold', SizeTieredCompactionStrategy)
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setter('min_sstable_size', SizeTieredCompactionStrategy)
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setter('sstable_size_in_mb', LeveledCompactionStrategy)
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return result
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def get_fields(model):
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# returns all fields that aren't part of the PK
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ks_name = model._get_keyspace()
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col_family = model.column_family_name(include_keyspace=False)
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query = "select * from system.schema_columns where keyspace_name = %s and columnfamily_name = %s"
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tmp = execute(query, [ks_name, col_family])
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# Tables containing only primary keys do not appear to create
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# any entries in system.schema_columns, as only non-primary-key attributes
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# appear to be inserted into the schema_columns table
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try:
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return [Field(x['column_name'], x['validator']) for x in tmp if x['type'] == 'regular']
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except KeyError:
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return [Field(x['column_name'], x['validator']) for x in tmp]
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# convert to Field named tuples
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def get_table_settings(model):
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# returns the table as provided by the native driver for a given model
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cluster = get_cluster()
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ks = model._get_keyspace()
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table = model.column_family_name(include_keyspace=False)
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table = cluster.metadata.keyspaces[ks].tables[table]
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return table
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def update_compaction(model):
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"""Updates the compaction options for the given model if necessary.
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:param model: The model to update.
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:return: `True`, if the compaction options were modified in Cassandra,
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`False` otherwise.
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:rtype: bool
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"""
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logger.debug("Checking %s for compaction differences", model)
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table = get_table_settings(model)
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existing_options = table.options.copy()
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existing_compaction_strategy = existing_options['compaction_strategy_class']
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existing_options = json.loads(existing_options['compaction_strategy_options'])
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desired_options = get_compaction_options(model)
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desired_compact_strategy = desired_options.get('class', SizeTieredCompactionStrategy)
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desired_options.pop('class', None)
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do_update = False
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if desired_compact_strategy not in existing_compaction_strategy:
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do_update = True
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for k, v in desired_options.items():
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val = existing_options.pop(k, None)
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if val != v:
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do_update = True
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# check compaction_strategy_options
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if do_update:
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options = get_compaction_options(model)
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# jsonify
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options = json.dumps(options).replace('"', "'")
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cf_name = model.column_family_name()
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query = "ALTER TABLE {} with compaction = {}".format(cf_name, options)
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logger.debug(query)
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execute(query)
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return True
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return False
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def delete_table(model):
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raise CQLEngineException("delete_table has been deprecated in favor of drop_table()")
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def drop_table(model):
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# don't try to delete non existant tables
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meta = get_cluster().metadata
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ks_name = model._get_keyspace()
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raw_cf_name = model.column_family_name(include_keyspace=False)
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try:
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table = meta.keyspaces[ks_name].tables[raw_cf_name]
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execute('drop table {};'.format(model.column_family_name(include_keyspace=True)))
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except KeyError:
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pass
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