nodetool disablefullquerylog

Disables full query logging (FQL) on the node.

---

Synopsis

nodetool [connection_options] disablefullquerylog

See connection options for connection options.

Description

nodetool disablefullquerylog deactivates full query logging on a Cassandra node. When disabled, the node stops recording query execution details to the FQL log files.

This command is typically used after completing performance analysis or debugging sessions where query logging was temporarily enabled.

Non-Persistent Setting

This setting is applied at runtime only and does not persist across node restarts. After a restart, full query logging reverts to the full_query_logging_options configuration in cassandra.yaml.

To permanently disable full query logging, ensure it is not configured in cassandra.yaml, or set:

full_query_logging_options:
    # log_dir: /var/log/cassandra/fql  # Comment out or remove to disable

---

Examples

Basic Usage

nodetool disablefullquerylog

Disable and Verify

nodetool disablefullquerylog
nodetool getfullquerylog
# Expected output includes: enabled: false

---

Behavior

When full query logging is disabled:

1. No new queries are logged
2. Existing log files remain on disk
3. Log archival continues for existing files
4. Disk I/O overhead from logging is eliminated

What Continues

Feature	Status
Existing FQL log files	Preserved
Archive command	Runs for existing logs
Query execution	Continues normally

What Stops

Feature	Status
New query logging	Stops
FQL log growth	Stops
Logging overhead	Eliminated

---

When to Use

After Performance Analysis

When analysis session is complete:

# Analysis complete
nodetool disablefullquerylog

# Process collected logs
fqltool dump /var/log/cassandra/fql/ > analysis_queries.txt

Emergency Disk Space

If FQL is consuming too much disk:

# Disable logging immediately
nodetool disablefullquerylog

# Check disk space recovered
df -h /var/log/cassandra/

# Clean up logs if needed
rm -rf /var/log/cassandra/fql/*

After Debugging Session

When issue investigation is complete:

# Debug session complete
nodetool disablefullquerylog

# Archive logs for reference
tar -czf debug_fql_$(date +%Y%m%d).tar.gz /var/log/cassandra/fql/
rm -rf /var/log/cassandra/fql/*

Performance Issue Resolution

If FQL is causing latency problems:

# Check current impact
nodetool proxyhistograms

# Disable FQL
nodetool disablefullquerylog

# Verify latency improvement
nodetool proxyhistograms

---

Impact Assessment

Immediate Effects

Aspect	Impact
Query logging	Stops immediately
Disk I/O	Decreases
Query latency	May improve (if blocking was enabled)
Log file growth	Stops

Performance Recovery

Metric	Expected Change
Write latency	May decrease
Disk utilization	Decreases
CPU usage	Slight decrease
Query throughput	May increase

---

Workflow: Complete FQL Session

fql_session.sh

#!/bin/bash
FQL_PATH="/var/log/cassandra/fql"
ARCHIVE_DIR="/archive/cassandra/fql"

echo "=== FQL Session Management ==="

# 1. Check if FQL is currently enabled
echo "1. Current FQL status:"
nodetool getfullquerylog

# 2. Disable FQL
echo ""
echo "2. Disabling FQL..."
nodetool disablefullquerylog

# 3. Verify disabled
echo ""
echo "3. Verification:"
nodetool getfullquerylog

# 4. Check captured data
echo ""
echo "4. Captured FQL data:"
if [ -d "$FQL_PATH" ] && [ "$(ls -A $FQL_PATH 2>/dev/null)" ]; then
    echo "Log directory size: $(du -sh $FQL_PATH)"
    echo "Query count: $(fqltool dump $FQL_PATH 2>/dev/null | wc -l)"
else
    echo "No FQL data found"
fi

# 5. Archive if requested
echo ""
read -p "Archive FQL logs? (y/n): " archive
if [ "$archive" = "y" ]; then
    mkdir -p $ARCHIVE_DIR
    archive_file="${ARCHIVE_DIR}/fql_$(date +%Y%m%d_%H%M%S).tar.gz"
    tar -czf $archive_file $FQL_PATH
    echo "Archived to: $archive_file"
fi

# 6. Clean up if requested
echo ""
read -p "Clean up FQL directory? (y/n): " cleanup
if [ "$cleanup" = "y" ]; then
    rm -rf ${FQL_PATH}/*
    echo "FQL directory cleaned"
fi

echo ""
echo "=== FQL Session Complete ==="

---

Managing FQL Logs After Disable

Preserve Logs

# After disabling, logs remain
ls -la /var/log/cassandra/fql/

# View log contents
fqltool dump /var/log/cassandra/fql/

Archive Logs

# Create archive
tar -czf fql_$(date +%Y%m%d).tar.gz /var/log/cassandra/fql/

# Move to archive location
mv fql_*.tar.gz /archive/cassandra/

Analyze Before Cleanup

# Quick analysis before cleanup
echo "Query Distribution:"
fqltool dump /var/log/cassandra/fql/ | grep -oE "^(SELECT|INSERT|UPDATE|DELETE)" | sort | uniq -c

echo ""
echo "Log Size:"
du -sh /var/log/cassandra/fql/

Clean Up Logs

# Remove all FQL logs
rm -rf /var/log/cassandra/fql/*

# Verify cleanup
du -sh /var/log/cassandra/fql/

---

Cluster-Wide Operations

Disable on All Nodes

disable_fql_cluster.sh

#!/bin/bash
echo "Disabling FQL cluster-wide..."# Get list of node IPs from local nodetool status


nodes=$(nodetool status | grep "^UN" | awk '{print $2}')

for node in $nodes; do
    echo -n "$node: "
    ssh "$node" "nodetool disablefullquerylog 2>/dev/null && echo "disabled" || echo "FAILED""
done

echo ""
echo "Verification:"
for node in $nodes; do
    echo -n "$node: "
    status=$(ssh "$node" "nodetool getfullquerylog 2>/dev/null | grep "enabled")"
    echo "$status"
done

Collect Logs from All Nodes

collect_fql_cluster.sh

#!/bin/bash
DEST_DIR="/data/fql_collection_$(date +%Y%m%d)"
mkdir -p $DEST_DIR# Get list of node IPs from local nodetool status


nodes=$(nodetool status | grep "^UN" | awk '{print $2}')

for node in $nodes; do
    echo "Collecting FQL from $node..."
    scp -r $node:/var/log/cassandra/fql/ $DEST_DIR/$node/
done

echo "FQL logs collected to $DEST_DIR"

---

Troubleshooting

Cannot Disable

# Check JMX connectivity
nodetool info

# Check for errors
grep -i "fql\|fullquery" /var/log/cassandra/system.log | tail -20

Logs Still Growing After Disable

# Verify disabled
nodetool getfullquerylog

# If still enabled, retry
nodetool disablefullquerylog

# Check for persistence in cassandra.yaml
grep -A 10 "full_query_logging" /etc/cassandra/cassandra.yaml

Performance Not Improved

# FQL may not have been the bottleneck
# Check other metrics
nodetool tpstats
nodetool compactionstats
iostat -x 1

---

Best Practices

Disable Guidelines

1. Disable when done - Don't leave FQL running indefinitely
2. Archive before cleanup - Preserve logs if analysis is needed
3. Check disk space - Verify space is freed after cleanup
4. Document findings - Record analysis results before cleanup
5. Cluster consistency - Disable on all nodes if enabled cluster-wide
6. Verify disabled - Always check with getfullquerylog

Post-Disable Workflow

After disabling FQL:

1. Verify disabled with getfullquerylog
2. Analyze captured logs with fqltool dump
3. Archive logs if needed for future reference
4. Clean up log directory to reclaim space
5. Document any findings from the analysis

---

Related Commands

Command	Relationship
enablefullquerylog	Enable FQL
getfullquerylog	View FQL configuration
resetfullquerylog	Reset FQL path
disableauditlog	Disable audit logging