Configuration

The configuration virtual tables provide CQL access to runtime settings, JVM system properties, and system logs without requiring shell access.

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Overview

These tables expose Cassandra's configuration state:

Table	Purpose
settings	Current cassandra.yaml settings (runtime values)
system_properties	JVM system properties
system_logs	Recent Cassandra log entries

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settings

Exposes current Cassandra configuration settings as key-value pairs. This reflects the active runtime configuration, which may differ from cassandra.yaml if settings were changed dynamically.

Schema

VIRTUAL TABLE system_views.settings (
    name text PRIMARY KEY,
    value text
) WITH comment = 'current settings';

Column	Type	Description
name	text	Configuration parameter name
value	text	Current value (as string)

Equivalent nodetool command: nodetool getconfig (Cassandra 5.0+)

Example Queries

-- All settings
SELECT name, value FROM system_views.settings;

Filter in application by name pattern (e.g., names containing 'compaction', 'timeout', 'heap').

Common Configuration Checks

-- Cluster identification
SELECT name, value FROM system_views.settings
WHERE name IN ('cluster_name', 'num_tokens', 'partitioner');

-- Network configuration
SELECT name, value FROM system_views.settings
WHERE name IN ('listen_address', 'rpc_address', 'broadcast_address',
               'native_transport_port', 'storage_port');

-- Compaction settings (setting name varies by version - see table below)
SELECT name, value FROM system_views.settings
WHERE name IN ('compaction_throughput', 'concurrent_compactors',
               'compaction_large_partition_warning_threshold');

-- Read/write settings
SELECT name, value FROM system_views.settings
WHERE name IN ('read_request_timeout', 'write_request_timeout',
               'range_request_timeout', 'counter_write_request_timeout');

-- Hinted handoff (setting name varies by version - see table below)
SELECT name, value FROM system_views.settings
WHERE name IN ('hinted_handoff_enabled', 'max_hint_window',
               'hinted_handoff_throttle', 'max_hints_delivery_threads');

-- Commit log
SELECT name, value FROM system_views.settings
WHERE name IN ('commitlog_sync', 'commitlog_sync_period',
               'commitlog_segment_size', 'commitlog_total_space');

-- Memtable configuration (setting name varies by version - see table below)
SELECT name, value FROM system_views.settings
WHERE name IN ('memtable_heap_space', 'memtable_offheap_space',
               'memtable_allocation_type', 'memtable_flush_writers');

Setting Name Changes by Version

Configuration setting names changed between Cassandra versions. Use the appropriate name for the target version:

Setting	Pre-4.1	4.1+
Compaction throughput	compaction_throughput_mb_per_sec	compaction_throughput
Stream throughput	stream_throughput_outbound_megabits_per_sec	stream_throughput_outbound
Inter-DC stream throughput	inter_dc_stream_throughput_outbound_megabits_per_sec	inter_dc_stream_throughput_outbound
Hinted handoff throttle	hinted_handoff_throttle_in_kb	hinted_handoff_throttle
Memtable heap space	memtable_heap_space_in_mb	memtable_heap_space
Memtable offheap space	memtable_offheap_space_in_mb	memtable_offheap_space

Duration and Size Literals

In Cassandra 4.1+, settings support duration literals (3h, 200ms) and size/rate units (64MiB, 16MiB/s). The old _in_ms, _in_mb, and _in_kb suffixed names are deprecated but still functional as aliases.

Configuration Audit

-- Check authentication/authorization settings
SELECT name, value FROM system_views.settings
WHERE name IN ('authenticator', 'authorizer', 'role_manager',
               'server_encryption_options', 'client_encryption_options');

Security check: Verify authenticator is not AllowAllAuthenticator and authorizer is not AllowAllAuthorizer in production.

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system_properties

Exposes JVM system properties relevant to Cassandra. Useful for verifying JVM configuration without shell access.

Schema

VIRTUAL TABLE system_views.system_properties (
    name text PRIMARY KEY,
    value text
) WITH comment = 'Cassandra relevant system properties';

Column	Type	Description
name	text	System property name
value	text	Property value

Example Queries

-- All system properties
SELECT name, value FROM system_views.system_properties;

Filter in application by name prefix (e.g., 'java.', 'cassandra.', 'os.').

Common Property Checks

-- JVM version
SELECT name, value FROM system_views.system_properties
WHERE name IN ('java.version', 'java.vendor', 'java.vm.name', 'java.vm.version');

-- Cassandra paths
SELECT name, value FROM system_views.system_properties
WHERE name IN ('cassandra.config', 'cassandra.storagedir', 'cassandra.logdir');

-- Operating system
SELECT name, value FROM system_views.system_properties
WHERE name IN ('os.name', 'os.version', 'os.arch');

-- User and file encoding
SELECT name, value FROM system_views.system_properties
WHERE name IN ('user.name', 'user.home', 'user.dir', 'file.encoding');

For GC settings and heap configuration, query all properties and filter in application.

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system_logs

Provides access to recent Cassandra log entries via CQL. Available in Cassandra 5.0+.

Schema

VIRTUAL TABLE system_views.system_logs (
    timestamp timestamp,
    order_in_millisecond int,
    level text,
    logger text,
    message text,
    PRIMARY KEY (timestamp, order_in_millisecond)
) WITH CLUSTERING ORDER BY (order_in_millisecond ASC)
    AND comment = 'Cassandra logs';

Column	Type	Description
timestamp	timestamp	Log entry timestamp
order_in_millisecond	int	Ordering within same millisecond
level	text	Log level (ERROR, WARN, INFO, DEBUG, TRACE)
logger	text	Logger name (class/component)
message	text	Log message content

Example Queries

-- All log entries
SELECT timestamp, level, logger, message
FROM system_views.system_logs;

-- Error messages
SELECT timestamp, logger, message
FROM system_views.system_logs
WHERE level = 'ERROR';

-- Warnings and errors
SELECT timestamp, level, logger, message
FROM system_views.system_logs
WHERE level IN ('ERROR', 'WARN');

Troubleshooting Queries

-- All log entries
SELECT timestamp, level, logger, message
FROM system_views.system_logs;

Filter in application by logger name or message content (e.g., 'Compaction', 'OutOfMemory').

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Monitoring Use Cases

Configuration Drift Detection

-- Export current settings for comparison
-- Run on each node and compare results
SELECT name, value FROM system_views.settings;

Exclude node-specific values (containing 'address') when comparing across nodes.

Security Audit

-- Authentication configuration
SELECT name, value FROM system_views.settings
WHERE name IN ('authenticator', 'authorizer', 'role_manager',
               'permissions_validity', 'credentials_validity');

-- Encryption settings
SELECT name, value FROM system_views.settings
WHERE name IN ('server_encryption_options', 'client_encryption_options');

-- Audit settings (Cassandra 4.0+)
SELECT name, value FROM system_views.settings
WHERE name IN ('audit_logging_options');

Removed Settings

native_transport_port_ssl was deprecated in Cassandra 4.x and removed in 5.0. Use client_encryption_options for SSL/TLS configuration.

Performance Configuration Review

-- Thread pool sizing (compare with thread_pools table)
SELECT name, value FROM system_views.settings
WHERE name IN ('concurrent_reads', 'concurrent_writes',
               'concurrent_counter_writes', 'concurrent_compactors');

-- Cache settings (compare with caches table)
SELECT name, value FROM system_views.settings
WHERE name IN ('key_cache_size_in_mb', 'row_cache_size_in_mb',
               'counter_cache_size_in_mb');

-- Throughput settings (use version-appropriate names)
-- Pre-4.1: compaction_throughput_mb_per_sec, stream_throughput_outbound_megabits_per_sec
-- 4.1+: compaction_throughput, stream_throughput_outbound
SELECT name, value FROM system_views.settings
WHERE name IN ('compaction_throughput', 'stream_throughput_outbound',
               'inter_dc_stream_throughput_outbound');

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Alerting Rules

Configuration Warnings

-- Security concerns
SELECT name, value FROM system_views.settings
WHERE (name = 'authenticator' AND value = 'AllowAllAuthenticator')
   OR (name = 'authorizer' AND value = 'AllowAllAuthorizer');

Error Log Monitoring

-- Recent errors (for alerting integration)
SELECT timestamp, logger, message
FROM system_views.system_logs
WHERE level = 'ERROR';

Filter in application for entries within the last 5 minutes.

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Comparison with nodetool

Information	nodetool Command	Virtual Table Query
View settings	nodetool getconfig	SELECT * FROM system_views.settings
Specific setting	nodetool getconfig <name>	SELECT value FROM system_views.settings WHERE name = '<name>'
System properties	N/A (check JVM)	SELECT * FROM system_views.system_properties
Logs	Filesystem access	SELECT * FROM system_views.system_logs

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Limitations

1. Settings table

   • Read-only; use nodetool setconfig for runtime changes
   • Values are strings; type conversion may be needed
   • Some settings require restart to change

2. System properties

   • Reflects JVM startup properties
   • Cannot be modified at runtime

3. System logs

   • Limited retention (recent entries only)
   • May not include all log levels depending on configuration
   • For full log history, use filesystem access or log aggregation

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Related Documentation

• Virtual Tables Overview - Introduction to virtual tables
• Thread Pools - Thread pool configuration and metrics
• Caches - Cache configuration and hit ratios
• Cassandra Configuration - Full configuration reference