# cassandra.metadata Schema and Ring Topology ### cassandra.metadata.cql_keywords Set of keywords in CQL. Derived from …/cassandra/src/java/org/apache/cassandra/cql3/Cql.g ### cassandra.metadata.cql_keywords_unreserved Set of unreserved keywords in CQL. Derived from …/cassandra/src/java/org/apache/cassandra/cql3/Cql.g ### cassandra.metadata.cql_keywords_reserved Set of reserved keywords in CQL. ### *class* cassandra.metadata.Metadata Holds a representation of the cluster schema and topology. #### cluster_name *= None* The string name of the cluster. #### partitioner *= None* The string name of the partitioner for the cluster. #### token_map *= None* A [`TokenMap`](#cassandra.metadata.TokenMap) instance describing the ring topology. #### keyspaces *= None* A map from keyspace names to matching [`KeyspaceMetadata`](#cassandra.metadata.KeyspaceMetadata) instances. #### dbaas *= False* A boolean indicating if connected to a DBaaS cluster #### export_schema_as_string() Returns a string that can be executed as a query in order to recreate the entire schema. The string is formatted to be human readable. #### get_replicas(keyspace, key) Returns a list of [`Host`](https://python-driver.docs.scylladb.com/stable/api/cassandra/pool.md#cassandra.pool.Host) instances that are replicas for a given partition key. #### add_or_return_host(host) Returns a tuple (host, new), where `host` is a Host instance, and `new` is a bool indicating whether the host was newly added. #### get_host(endpoint_or_address, port=None) Find a host in the metadata for a specific endpoint. If a string inet address and port are passed, iterate all hosts to match the [`broadcast_rpc_address`](https://python-driver.docs.scylladb.com/stable/api/cassandra/pool.md#cassandra.pool.Host.broadcast_rpc_address) and [`broadcast_rpc_port`](https://python-driver.docs.scylladb.com/stable/api/cassandra/pool.md#cassandra.pool.Host.broadcast_rpc_port) attributes. #### get_host_by_host_id(host_id) Same as get_host() but use host_id for lookup. #### all_hosts() Returns a list of all known [`Host`](https://python-driver.docs.scylladb.com/stable/api/cassandra/pool.md#cassandra.pool.Host) instances in the cluster. ## Schemas ### *class* cassandra.metadata.KeyspaceMetadata A representation of the schema for a single keyspace. #### virtual *= False* A boolean indicating if this is a virtual keyspace or not. Always `False` for clusters running Cassandra pre-4.0 and DSE pre-6.7 versions. #### Versionadded Added in version 3.15. #### name *= None* The string name of the keyspace. #### durable_writes *= True* A boolean indicating whether durable writes are enabled for this keyspace or not. #### replication_strategy *= None* A [`ReplicationStrategy`](#cassandra.metadata.ReplicationStrategy) subclass object. #### tables *= None* A map from table names to instances of [`TableMetadata`](#cassandra.metadata.TableMetadata). #### indexes *= None* A dict mapping index names to [`IndexMetadata`](#cassandra.metadata.IndexMetadata) instances. #### user_types *= None* A map from user-defined type names to instances of [`UserType`](#cassandra.metadata.UserType). #### Versionadded Added in version 2.1.0. #### functions *= None* A map from user-defined function signatures to instances of [`Function`](#cassandra.metadata.Function). #### Versionadded Added in version 2.6.0. #### aggregates *= None* A map from user-defined aggregate signatures to instances of [`Aggregate`](#cassandra.metadata.Aggregate). #### Versionadded Added in version 2.6.0. #### views *= None* A dict mapping view names to [`MaterializedViewMetadata`](#cassandra.metadata.MaterializedViewMetadata) instances. #### graph_engine *= None* A string indicating whether a graph engine is enabled for this keyspace (Core/Classic). #### export_as_string() Returns a CQL query string that can be used to recreate the entire keyspace, including user-defined types and tables. #### as_cql_query() Returns a CQL query string that can be used to recreate just this keyspace, not including user-defined types and tables. ### *class* cassandra.metadata.UserType A user defined type, as created by `CREATE TYPE` statements. User-defined types were introduced in Cassandra 2.1. #### Versionadded Added in version 2.1.0. #### keyspace *= None* The string name of the keyspace in which this type is defined. #### name *= None* The name of this type. #### field_names *= None* An ordered list of the names for each field in this user-defined type. #### field_types *= None* An ordered list of the types for each field in this user-defined type. #### as_cql_query(formatted=False) Returns a CQL query that can be used to recreate this type. If formatted is set to `True`, extra whitespace will be added to make the query more readable. ### *class* cassandra.metadata.Function A user defined function, as created by `CREATE FUNCTION` statements. User-defined functions were introduced in Cassandra 2.2 #### Versionadded Added in version 2.6.0. #### keyspace *= None* The string name of the keyspace in which this function is defined #### name *= None* The name of this function #### argument_types *= None* An ordered list of the types for each argument to the function #### argument_names *= None* An ordered list of the names of each argument to the function #### return_type *= None* Return type of the function #### language *= None* Language of the function body #### body *= None* Function body string #### called_on_null_input *= None* Flag indicating whether this function should be called for rows with null values (convenience function to avoid handling nulls explicitly if the result will just be null) #### deterministic *= None* Flag indicating if this function is guaranteed to produce the same result for a particular input. This is available only for DSE >=6.0. #### monotonic *= None* Flag indicating if this function is guaranteed to increase or decrease monotonically on any of its arguments. This is available only for DSE >=6.0. #### monotonic_on *= None* A list containing the argument or arguments over which this function is monotonic. This is available only for DSE >=6.0. #### as_cql_query(formatted=False) Returns a CQL query that can be used to recreate this function. If formatted is set to `True`, extra whitespace will be added to make the query more readable. ### *class* cassandra.metadata.Aggregate A user defined aggregate function, as created by `CREATE AGGREGATE` statements. Aggregate functions were introduced in Cassandra 2.2 #### Versionadded Added in version 2.6.0. #### keyspace *= None* The string name of the keyspace in which this aggregate is defined #### name *= None* The name of this aggregate #### argument_types *= None* An ordered list of the types for each argument to the aggregate #### state_func *= None* Name of a state function #### state_type *= None* Type of the aggregate state #### final_func *= None* Name of a final function #### initial_condition *= None* Initial condition of the aggregate #### return_type *= None* Return type of the aggregate #### deterministic *= None* Flag indicating if this function is guaranteed to produce the same result for a particular input and state. This is available only with DSE >=6.0. #### as_cql_query(formatted=False) Returns a CQL query that can be used to recreate this aggregate. If formatted is set to `True`, extra whitespace will be added to make the query more readable. ### *class* cassandra.metadata.TableMetadata A representation of the schema for a single table. #### *property* primary_key A list of [`ColumnMetadata`](#cassandra.metadata.ColumnMetadata) representing the components of the primary key for this table. #### *property* is_cql_compatible A boolean indicating if this table can be represented as CQL in export #### extensions *= None* Metadata describing configuration for table extensions #### keyspace_name *= None* String name of this Table’s keyspace #### name *= None* The string name of the table. #### partition_key *= None* A list of [`ColumnMetadata`](#cassandra.metadata.ColumnMetadata) instances representing the columns in the partition key for this table. This will always hold at least one column. #### clustering_key *= None* A list of [`ColumnMetadata`](#cassandra.metadata.ColumnMetadata) instances representing the columns in the clustering key for this table. These are all of the [`primary_key`](#cassandra.metadata.TableMetadata.primary_key) columns that are not in the [`partition_key`](#cassandra.metadata.TableMetadata.partition_key). Note that a table may have no clustering keys, in which case this will be an empty list. #### columns *= None* A dict mapping column names to [`ColumnMetadata`](#cassandra.metadata.ColumnMetadata) instances. #### indexes *= None* A dict mapping index names to [`IndexMetadata`](#cassandra.metadata.IndexMetadata) instances. #### options *= None* A dict mapping table option names to their specific settings for this table. #### triggers *= None* A dict mapping trigger names to `TriggerMetadata` instances. #### views *= None* A dict mapping view names to [`MaterializedViewMetadata`](#cassandra.metadata.MaterializedViewMetadata) instances. #### virtual *= False* A boolean indicating if this is a virtual table or not. Always `False` for clusters running Cassandra pre-4.0 and DSE pre-6.7 versions. #### Versionadded Added in version 3.15. #### export_as_string() Returns a string of CQL queries that can be used to recreate this table along with all indexes on it. The returned string is formatted to be human readable. #### as_cql_query(formatted=False) Returns a CQL query that can be used to recreate this table (index creations are not included). If formatted is set to `True`, extra whitespace will be added to make the query human readable. ### *class* cassandra.metadata.TableMetadataV3 For C\* 3.0+. option_maps take a superset of map names, so if nothing changes structurally, new option maps can just be appended to the list. #### *property* is_cql_compatible A boolean indicating if this table can be represented as CQL in export ### *class* cassandra.metadata.TableMetadataDSE68 #### vertex *= None* A [`VertexMetadata`](#cassandra.metadata.VertexMetadata) instance, if graph enabled #### edge *= None* A [`EdgeMetadata`](#cassandra.metadata.EdgeMetadata) instance, if graph enabled #### as_cql_query(formatted=False) Returns a CQL query that can be used to recreate this table (index creations are not included). If formatted is set to `True`, extra whitespace will be added to make the query human readable. ### *class* cassandra.metadata.ColumnMetadata A representation of a single column in a table. #### table *= None* The [`TableMetadata`](#cassandra.metadata.TableMetadata) this column belongs to. #### name *= None* The string name of this column. #### cql_type *= None* The CQL type for the column. #### is_static *= False* If this column is static (available in Cassandra 2.1+), this will be `True`, otherwise `False`. #### is_reversed *= False* If this column is reversed (DESC) as in clustering order ### *class* cassandra.metadata.IndexMetadata A representation of a secondary index on a column. #### keyspace_name *= None* A string name of the keyspace. #### table_name *= None* A string name of the table this index is on. #### name *= None* A string name for the index. #### kind *= None* A string representing the kind of index (COMPOSITE, CUSTOM,…). #### index_options *= {}* A dict of index options. #### as_cql_query() Returns a CQL query that can be used to recreate this index. #### export_as_string() Returns a CQL query string that can be used to recreate this index. ### *class* cassandra.metadata.MaterializedViewMetadata A representation of a materialized view on a table #### extensions *= None* Metadata describing configuration for table extensions #### keyspace_name *= None* A string name of the keyspace of this view. #### name *= None* A string name of the view. #### base_table_name *= None* A string name of the base table for this view. #### partition_key *= None* A list of [`ColumnMetadata`](#cassandra.metadata.ColumnMetadata) instances representing the columns in the partition key for this view. This will always hold at least one column. #### clustering_key *= None* A list of [`ColumnMetadata`](#cassandra.metadata.ColumnMetadata) instances representing the columns in the clustering key for this view. Note that a table may have no clustering keys, in which case this will be an empty list. #### columns *= None* A dict mapping column names to [`ColumnMetadata`](#cassandra.metadata.ColumnMetadata) instances. #### include_all_columns *= None* A flag indicating whether the view was created AS SELECT \* #### where_clause *= None* String WHERE clause for the view select statement. From server metadata #### options *= None* A dict mapping table option names to their specific settings for this view. #### as_cql_query(formatted=False) Returns a CQL query that can be used to recreate this function. If formatted is set to `True`, extra whitespace will be added to make the query more readable. ### *class* cassandra.metadata.VertexMetadata A representation of a vertex on a table #### keyspace_name *= None* A string name of the keyspace. #### table_name *= None* A string name of the table this vertex is on. #### label_name *= None* A string name of the label of this vertex. ### *class* cassandra.metadata.EdgeMetadata A representation of an edge on a table #### keyspace_name *= None* A string name of the keyspace #### table_name *= None* A string name of the table this edge is on #### label_name *= None* A string name of the label of this edge #### from_table *= None* A string name of the from table of this edge (incoming vertex) #### from_label *= None* A string name of the from table label of this edge (incoming vertex) #### from_partition_key_columns *= None* The columns that match the partition key of the incoming vertex table. #### from_clustering_columns *= None* The columns that match the clustering columns of the incoming vertex table. #### to_table *= None* A string name of the to table of this edge (outgoing vertex) #### to_label *= None* A string name of the to table label of this edge (outgoing vertex) #### to_partition_key_columns *= None* The columns that match the partition key of the outgoing vertex table. #### to_clustering_columns *= None* The columns that match the clustering columns of the outgoing vertex table. ## Tokens and Ring Topology ### *class* cassandra.metadata.TokenMap Information about the layout of the ring. #### token_class *= None* A subclass of [`Token`](#cassandra.metadata.Token), depending on what partitioner the cluster uses. #### ring *= None* An ordered list of [`Token`](#cassandra.metadata.Token) instances in the ring. #### token_to_host_owner *= None* A map of [`Token`](#cassandra.metadata.Token) objects to the [`Host`](https://python-driver.docs.scylladb.com/stable/api/cassandra/pool.md#cassandra.pool.Host) that owns that token. #### tokens_to_hosts_by_ks *= None* A map of keyspace names to a nested map of [`Token`](#cassandra.metadata.Token) objects to sets of [`Host`](https://python-driver.docs.scylladb.com/stable/api/cassandra/pool.md#cassandra.pool.Host) objects. #### get_replicas(keyspace, token) Get a set of [`Host`](https://python-driver.docs.scylladb.com/stable/api/cassandra/pool.md#cassandra.pool.Host) instances representing all of the replica nodes for a given [`Token`](#cassandra.metadata.Token). ### *class* cassandra.metadata.Token Abstract class representing a token. ### *class* cassandra.metadata.Murmur3Token(token) A token for `Murmur3Partitioner`. token is an int or string representing the token. ### *class* cassandra.metadata.MD5Token(token) A token for `RandomPartitioner`. ### *class* cassandra.metadata.BytesToken(token) A token for `ByteOrderedPartitioner`. #### *classmethod* from_string(token_string) token_string should be the string representation from the server. ### cassandra.metadata.ReplicationStrategy alias of `_ReplicationStrategy` ### *class* cassandra.metadata.ReplicationFactor(all_replicas, transient_replicas=None) Represent the replication factor of a keyspace. #### all_replicas *= None* The number of total replicas. #### transient_replicas *= None* The number of transient replicas. Only set if the keyspace has transient replication enabled. #### full_replicas *= None* The number of replicas that own a full copy of the data. This is the same than all_replicas when transient replication is not enabled. ### *class* cassandra.metadata.SimpleStrategy(options_map) #### *property* replication_factor The replication factor for this keyspace. For backward compatibility, this returns the [`cassandra.metadata.ReplicationFactor.full_replicas`](#cassandra.metadata.ReplicationFactor.full_replicas) value of [`cassandra.metadata.SimpleStrategy.replication_factor_info`](#cassandra.metadata.SimpleStrategy.replication_factor_info). #### replication_factor_info *= None* A [`cassandra.metadata.ReplicationFactor`](#cassandra.metadata.ReplicationFactor) instance. #### export_for_schema() Returns a string version of these replication options which are suitable for use in a CREATE KEYSPACE statement. ### *class* cassandra.metadata.NetworkTopologyStrategy(dc_replication_factors) #### dc_replication_factors_info *= None* A map of datacenter names to the [`cassandra.metadata.ReplicationFactor`](#cassandra.metadata.ReplicationFactor) instance for that DC. #### dc_replication_factors *= None* A map of datacenter names to the replication factor for that DC. For backward compatibility, this maps to the [`cassandra.metadata.ReplicationFactor.full_replicas`](#cassandra.metadata.ReplicationFactor.full_replicas) value of the [`cassandra.metadata.NetworkTopologyStrategy.dc_replication_factors_info`](#cassandra.metadata.NetworkTopologyStrategy.dc_replication_factors_info) dict. #### export_for_schema() Returns a string version of these replication options which are suitable for use in a CREATE KEYSPACE statement. ### *class* cassandra.metadata.LocalStrategy(options_map) #### export_for_schema() Returns a string version of these replication options which are suitable for use in a CREATE KEYSPACE statement. ### cassandra.metadata.group_keys_by_replica(session, keyspace, table, keys) Returns a `dict` with the keys grouped per host. This can be used to more accurately group by IN clause or to batch the keys per host. If a valid replica is not found for a particular key it will be grouped under `NO_VALID_REPLICA` Example usage: ```default >>> result = group_keys_by_replica( ... session, "system", "peers", ... (("127.0.0.1", ), ("127.0.0.2", ))) ```