SSTable to JSON one-liner

SSTable to JSON one-liner

Task: Dump all rows from a table to a JSON array on stdout.

cqlite \
  --schema test-data/schemas/basic-types.cql \
  --data-dir test-data/datasets/sstables \
  --query "SELECT id, name, age FROM test_basic.simple_table LIMIT 3" \
  --out json

Expected output shape (real output, trimmed to 3 rows):

[
  {
    "id": "0023ece7-7c4e-4705-9068-d1a59ec5fe19",
    "name": "Debbie Soto",
    "age": 79
  },
  {
    "id": "009fb913-7173-40df-b4ea-67ed6834cfe5",
    "name": "Richard Parker",
    "age": 58
  },
  {
    "id": "00a74226-9bde-4259-9ba0-d74359e8013e",
    "name": "Andrew Meyers",
    "age": 47
  }
]

Exit code: 0 on success.

Output format:

• Array of objects, one object per row.
• Written to stdout; redirect with --output /path/to/out.json.
• INFO/WARN log lines go to stderr; stdout is clean JSON.

Dump all columns

Omit the column list in the SELECT to retrieve all columns:

cqlite \
  --schema test-data/schemas/basic-types.cql \
  --data-dir test-data/datasets/sstables \
  --query "SELECT * FROM test_basic.simple_table LIMIT 1" \
  --out json

Expected keys (19 columns in simple_table; null columns omitted from objects):

id, name, age, salary, height, weight, active, created, birth_date,
work_time, description, account_balance, session_id, ip_address,
small_number, medium_number, duration_val, varchar_field, large_int

Write to a file

cqlite \
  --schema test-data/schemas/basic-types.cql \
  --data-dir test-data/datasets/sstables \
  --query "SELECT * FROM test_basic.simple_table" \
  --out json \
  --output /tmp/simple_table.json

Use --overwrite to replace an existing file (exit code 6 if the file exists and --overwrite is not set).

Failure modes

Symptom	Error text	Fix
No --schema flag	Error: Schema not found for table 'simple_table'	Add --schema path/to/schema.cql
Wrong table name	Error: Schema not found for table 'bad_name'	Check table name matches schema
Output file exists	exit code 6	Add --overwrite
BTI-format SSTable	WARN on stderr, 0 rows returned	BTI (da- prefix) not supported; use nb- SSTables

Type mapping

See the full type map in Output Formats.

Key rules:

• UUIDs → string ("0023ece7-...")
• Timestamps → string ("2025-10-06 01:00:30.616+0000")
• Booleans → true / false
• Integers → JSON number
• Floats → JSON number (may include rounding artifacts)
• null columns are omitted from the JSON object (not rendered as null)