About system keyspace tables 

Provides details about database objects and cluster configuration in the system keyspace tables.

The system keyspace includes a number of tables that contain details about your database objects and cluster configuration.
Columns in system tables
Table name Column name Comment
available_ranges keyspace_name, ranges  
batches id, mutations, version  
batchlog id, data, version, written_at  
built_views keyspace_name, view_name Information on materialized views
compaction_history id, bytes_in, bytes_out, columnfamily_name, compacted_at, keyspace_name, rows_merged Information on compaction history
hints target_id, hint_id, message_version, mutation  
"IndexInfo" table_name, index_name Information on indexes
local key, bootstrapped, broadcast_address, cluster_name, cql_version, data_center, gossip_generation, host_id, listen_address, native_protocol_version, partitioner, rack, release_version, rpc_address, schema_version, thrift_version, tokens, truncated_at map Information on a node has about itself and a superset of gossip.
paxos row_key, cf_id, in_progress_ballot, most_recent_commit, most_recent_commit_at, most_recent_commit_version, proposal, proposal_ballot, proposal_version Information on lightweight Paxos transactions
peers peer, data_center, host_id, preferred_ip, rack, release_version, rpc_address, schema_version, tokens Each node records what other nodes tell it about themselves over the gossip.
peer_events peer, hints_dropped  

prepared_id, logged_keyspace, query_string

Prepared statements used by drivers for queries.
range_xfers token_bytes,requested_at  
size_estimates keyspace_name, table_name, range_start, range_end, mean_partition_size, partitions_count Information on partitions
sstable_activity keyspace_name, columnfamily_name, generation, rate_120m, rate_15m  
views_builds_in_progress keyspace_name, view_name, generation_number, last_token  
Columns in system_schema tables
Table name Column name Comment
aggregates keyspace_name, aggregate_name, argument_types, final_func, initcond, return_type, state_func, state_type Information about user-defined aggregates
columns keyspace_name, table_name, column_name, clustering_order, column_name_bytes, kind, position, type Information about table columns
dropped_columns keyspace_name, table_name, column_name, dropped_time,type Information about dropped columns
functions keyspace_name, function_name, argument_types, argument_names, body, called_on_null_input,language,return_type Information on user-defined functions
indexes keyspace_name, table_name, index_name, kind,options Information about indexes
keyspaces keyspace_name, durable_writes, replication Information on keyspace durable writes and replication
tables keyspace_name, table_name, bloom_filter_fp_chance, caching, comment, compaction, compression, crc_check_chance, dclocal_read_repair_chance, default_time_to_live, extensions, flags, gc_grace_seconds, id, max_index_interval, memtable_flush_period_in_ms, min_index_interval, read_repair_chance, speculative_retry Information on columns and column indexes. Used internally for compound primary keys.
triggers keyspace_name, table_name, trigger_name, options Information on triggers
types keyspace_name, type_name, field_names, field_types Information about user-defined types
views keyspace_name, view_name, base_table_id, base_table_name, bloom_filter_fp_chance, caching, comment, compaction, compression, crc_check_chance, dclocal_read_repair_chance, default_time_to_live, extensions, flags,gc_grace_seconds, include_all_columns, max_index_interval, memtable_flush_period_in_ms, min_index_interval, read_repair_chance, speculative_retry, where_clause Information about materialized views
Columns in system_distributed tables
Table name Column names Comment
repair_history keyspace_name, columnfamily_name, id, coordinator, exception_message, exception_stacktrace, finished_at, parent_id, participants, range_begin, range_end, started_at, status Contains detailed information on keyspace repair history.