UNEXPECTED_END_OF_FILE ClickHouse error¶

This error occurs when ClickHouse encounters an unexpected end of file during data processing. It's common with corrupted data files, incomplete imports, or malformed data streams.

The UNEXPECTED_END_OF_FILE error in ClickHouse (and Tinybird) happens when the system encounters an unexpected end of file during data processing operations. This typically occurs when data files are corrupted, incomplete, or malformed, or when data streams are interrupted unexpectedly during import operations.

What causes this error¶

You'll typically see it when:

Data files are corrupted or incomplete
File import operations are interrupted
Data streams end unexpectedly
Malformed data files with missing content
Network interruptions during file transfer
Incomplete data uploads
Corrupted backup or archive files
File system issues causing truncation
Memory issues during large file processing

This error often indicates data corruption or incomplete transfers. Check file integrity and retry the operation.

Example errors¶

Fails: corrupted data file

INSERT INTO events FROM INFILE '/path/to/corrupted_file.csv'
-- Error: UNEXPECTED_END_OF_FILE

Fails: incomplete import

INSERT INTO users FROM INFILE '/path/to/incomplete_users.csv'
-- Error: UNEXPECTED_END_OF_FILE

Fails: interrupted data stream

-- When streaming data from external source
INSERT INTO metrics FROM INFILE '/path/to/streaming_data.csv'
-- Error: UNEXPECTED_END_OF_FILE

Fails: malformed JSON file

INSERT INTO json_data FROM INFILE '/path/to/malformed.json'
-- Error: UNEXPECTED_END_OF_FILE

How to fix it¶

Check file integrity¶

Verify the file is complete and not corrupted:

Check file integrity

-- Check file size and basic integrity
-- Example for Linux:
-- ls -la /path/to/your_file.csv
-- file /path/to/your_file.csv
-- md5sum /path/to/your_file.csv
--
-- Example for Python:
-- import os
-- file_size = os.path.getsize('/path/to/your_file.csv')
-- print(f"File size: {file_size} bytes")

Verify file completion¶

Ensure the file transfer or creation completed successfully:

Verify file completion

-- Check if file transfer completed
-- Example for Linux:
-- tail -n 5 /path/to/your_file.csv
-- wc -l /path/to/your_file.csv
--
-- Example for Python:
-- with open('/path/to/your_file.csv', 'r') as f:
--     lines = f.readlines()
--     print(f"Total lines: {len(lines)}")
--     print(f"Last line: {lines[-1] if lines else 'Empty file'}")

Check file format¶

Verify the file format is correct:

Check file format

-- Validate CSV format
-- Example for Python:
-- import csv
-- try:
--     with open('/path/to/your_file.csv', 'r') as f:
--         reader = csv.reader(f)
--         for i, row in enumerate(reader):
--             if i == 0:  # Check header
--                 print(f"Header: {row}")
--             if i < 5:   # Check first few rows
--                 print(f"Row {i}: {row}")
-- except Exception as e:
--     print(f"File format error: {e}")

Retry the operation¶

Attempt the import operation again:

Retry import

-- Try importing again with the same file
INSERT INTO events FROM INFILE '/path/to/your_file.csv'
FORMAT CSV
SETTINGS
    input_format_allow_errors_num = 10,
    input_format_allow_errors_ratio = 0.1

Common patterns and solutions¶

File validation¶

Implement file validation before import:

File validation

-- Validate file before import
-- Example pseudo-code:
--
-- def validate_file(file_path):
--     try:
--         # Check file exists
--         if not os.path.exists(file_path):
--             return False, "File does not exist"
--
--         # Check file size
--         file_size = os.path.getsize(file_path)
--         if file_size == 0:
--             return False, "File is empty"
--
--         # Check file format
--         with open(file_path, 'r') as f:
--             first_line = f.readline().strip()
--             if not first_line:
--                 return False, "File appears to be empty"
--
--         return True, "File is valid"
--     except Exception as e:
--         return False, f"Validation error: {e}"

Error-tolerant import¶

Use error-tolerant import settings:

Error-tolerant import

-- Import with error tolerance
INSERT INTO events FROM INFILE '/path/to/your_file.csv'
FORMAT CSV
SETTINGS
    input_format_allow_errors_num = 100,        -- Allow up to 100 errors
    input_format_allow_errors_ratio = 0.05,     -- Allow up to 5% errors
    input_format_skip_unknown_fields = 1,       -- Skip unknown fields
    input_format_null_as_default = 1            -- Use defaults for NULL values

Incremental import¶

Import data in smaller chunks:

Incremental import

-- Import in smaller chunks to avoid file issues
-- Example pseudo-code:
--
-- def import_in_chunks(file_path, chunk_size=10000):
--     with open(file_path, 'r') as f:
--         header = f.readline()  # Skip header
--
--         chunk = []
--         for i, line in enumerate(f):
--             chunk.append(line)
--
--             if len(chunk) >= chunk_size:
--                 # Import chunk
--                 import_chunk(chunk)
--                 chunk = []
--
--         # Import remaining lines
--         if chunk:
--             import_chunk(chunk)

File repair¶

Attempt to repair corrupted files:

File repair

-- Try to repair corrupted files
-- Example pseudo-code:
--
-- def repair_file(file_path):
--     try:
--         # Read file and remove corrupted lines
--         with open(file_path, 'r') as f:
--             lines = f.readlines()
--
--         # Filter out corrupted lines
--         valid_lines = []
--         for line in lines:
--             if line.strip() and len(line.split(',')) == expected_columns:
--                 valid_lines.append(line)
--
--         # Write repaired file
--         with open(file_path + '.repaired', 'w') as f:
--             f.writelines(valid_lines)
--
--         return file_path + '.repaired'
--     except Exception as e:
--         print(f"Repair failed: {e}")
--         return None

Tinybird-specific notes¶

In Tinybird, UNEXPECTED_END_OF_FILE errors often occur when:

Data Source imports are interrupted
File uploads are incomplete
Pipe transformations encounter corrupted data
External data sources have connectivity issues
Data streaming operations are interrupted

To debug in Tinybird:

Check Data Source import status
Verify file upload completion
Review Pipe transformation logs
Check external data source connectivity

In Tinybird, use the Data Source preview to validate data before processing it in Pipes.

Best practices¶

File handling¶

Validate files before import
Implement checksums for file integrity
Use error-tolerant import settings
Monitor import operations for completion

Error handling¶

Implement retry logic for failed imports
Log file validation results
Provide clear error messages
Handle partial import failures gracefully

Data quality¶

Validate data format before import
Check for data corruption indicators
Implement data quality checks
Monitor import success rates

Configuration options¶

Import settings¶

Import configuration

-- Configure import behavior
SET input_format_allow_errors_num = 100;
SET input_format_allow_errors_ratio = 0.05;
SET input_format_skip_unknown_fields = 1;
SET input_format_null_as_default = 1;

File processing settings¶

File processing configuration

-- Configure file processing
SET max_insert_block_size = 1000000;
SET min_insert_block_size_rows = 1000;
SET min_insert_block_size_bytes = 1000000;

Error handling settings¶

Error handling configuration

-- Configure error handling
SET max_errors_to_log = 1000;
SET log_error_rate_prob = 1.0;
SET log_errors = 1;

Alternative solutions¶

Use streaming import¶

Import data in streaming mode:

Streaming import

-- Use streaming import for large files
INSERT INTO events FROM INFILE '/path/to/your_file.csv'
FORMAT CSV
SETTINGS
    input_format_parallel_parsing = 1,
    max_insert_block_size = 100000,
    min_insert_block_size_rows = 1000

Implement file monitoring¶

Monitor file import progress:

File monitoring

-- Monitor import progress
-- Example pseudo-code:
--
-- class FileImportMonitor:
--     def __init__(self, file_path):
--         self.file_path = file_path
--         self.total_lines = 0
--         self.processed_lines = 0
--
--     def start_monitoring(self):
--         # Count total lines
--         with open(self.file_path, 'r') as f:
--             self.total_lines = sum(1 for line in f)
--
--         print(f"Total lines to process: {self.total_lines}")
--
--     def update_progress(self, processed):
--         self.processed_lines = processed
--         progress = (processed / self.total_lines) * 100
--         print(f"Progress: {progress:.2f}% ({processed}/{self.total_lines})")

Use backup files¶

Implement backup and recovery:

Backup and recovery

-- Implement backup strategy
-- Example pseudo-code:
--
-- def backup_file(file_path):
--     import shutil
--     from datetime import datetime
--
--     timestamp = datetime.now().strftime('%Y%m%d_%H%M%S')
--     backup_path = f"{file_path}.backup_{timestamp}"
--
--     shutil.copy2(file_path, backup_path)
--     print(f"Backup created: {backup_path}")
--     return backup_path
--
-- def restore_from_backup(backup_path, original_path):
--     shutil.copy2(backup_path, original_path)
--     print(f"File restored from backup: {backup_path}")

Monitoring and prevention¶

Import monitoring¶

Import tracking

-- Monitor import operations
-- Example pseudo-code:
--
-- def track_import_operation(file_path, operation_type, status, error=None):
--     logger.info(f"Import operation: {operation_type} on {file_path}")
--     logger.info(f"Status: {status}")
--
--     if error:
--         logger.error(f"Import error: {error}")
--
--     # Track import metrics
--     increment_counter('import_operations', {
--         'file_path': file_path,
--         'operation_type': operation_type,
--         'status': status,
--         'error': error
--     })

File health monitoring¶

File health tracking

-- Monitor file health metrics
-- Example pseudo-code:
--
-- class FileHealthMonitor:
--     def __init__(self):
--         self.file_checks = []
--
--     def check_file_health(self, file_path):
--         try:
--             # Check file size
--             file_size = os.path.getsize(file_path)
--
--             # Check file readability
--             with open(file_path, 'r') as f:
--                 first_line = f.readline()
--                 last_line = None
--                 line_count = 0
--
--                 for line in f:
--                     last_line = line
--                     line_count += 1
--
--             health_status = {
--                 'file_path': file_path,
--                 'file_size': file_size,
--                 'line_count': line_count,
--                 'first_line': first_line.strip() if first_line else None,
--                 'last_line': last_line.strip() if last_line else None,
--                 'status': 'healthy'
--             }
--
--             self.file_checks.append(health_status)
--             return health_status
--
--         except Exception as e:
--             health_status = {
--                 'file_path': file_path,
--                 'status': 'unhealthy',
--                 'error': str(e)
--             }
--             self.file_checks.append(health_status)
--             return health_status

Error prevention¶

Error prevention

-- Implement error prevention measures
-- Example pseudo-code:
--
-- def prevent_file_errors(file_path):
--     # Check file before processing
--     if not os.path.exists(file_path):
--         raise FileNotFoundError(f"File not found: {file_path}")
--
--     # Check file size
--     file_size = os.path.getsize(file_path)
--     if file_size == 0:
--         raise ValueError(f"File is empty: {file_path}")
--
--     # Check file permissions
--     if not os.access(file_path, os.R_OK):
--         raise PermissionError(f"Cannot read file: {file_path}")
--
--     # Validate file format
--     validate_file_format(file_path)