Export SSTable for Cassandra import

Export SSTable for Cassandra import

Task: Export rows written through CQLite’s write engine as Cassandra-compatible SSTable files for use with sstableloader or direct Cassandra data directory placement.

Prerequisite: The CLI must be built with write support:

cargo build --package cqlite-cli --features write-support

Full workflow: write, flush, then export

The export-sstable subcommand re-exports data from the write engine’s SSTable output. You must write and flush mutations before exporting. The three steps below run in sequence.

cqlite \
  --schema test-data/schemas/write-test.cql \
  --data-dir test-data/datasets/sstables \
  --writable \
  --write-dir /tmp/cqlite-write \
  --mutation '{"table":{"keyspace":"test_basic","table":"simple_table"},"partition_key":{"columns":[["id",{"Uuid":[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]}]]},"clustering_key":null,"operations":[{"Write":{"column":"name","value":{"Text":"Export Test"}}}],"timestamp_micros":1704067200000000,"ttl_seconds":null,"partition_tombstone":null,"range_tombstones":[]}' \
  --flush && \
cqlite \
  --schema test-data/schemas/write-test.cql \
  --data-dir test-data/datasets/sstables \
  --writable \
  --write-dir /tmp/cqlite-write \
  export-sstable /tmp/cqlite-export \
  --keyspace test_basic \
  --table simple_table

Expected output (real output):

Export complete:
  Output: /tmp/cqlite-export/test_basic/simple_table
  Rows: 2
  Size: 50 bytes
  Time: 2.0ms

Exit code: 0 on success.

The exported SSTable files are placed at:

/tmp/cqlite-export/
└── test_basic/
    └── simple_table/
        └── nb-1-big-Data.db
        ...

Export flags

Flag	Required	Description
<output-dir>	Yes	Base directory for exported SSTables
--keyspace	Yes	Keyspace to export
--table	Yes	Table to export

Use with sstableloader

To import exported SSTables into a running Cassandra cluster:

sstableloader -d <cassandra-host> /tmp/cqlite-export/test_basic/simple_table

The output directory structure (<keyspace>/<table>/) matches the path layout expected by sstableloader.

Note: CQLite writes nb-format (Cassandra 5.0 BigTable) SSTables. These are compatible with Cassandra 5.0+. Cassandra 4.x uses mc-format and cannot read nb files directly.

Export requires —writable mode

If --writable is omitted, the export subcommand fails:

cqlite \
  --schema test-data/schemas/write-test.cql \
  --data-dir test-data/datasets/sstables \
  export-sstable /tmp/export --keyspace test_basic --table simple_table

Error:

Error: Export requires --writable mode

Exit code: 0 (error is printed but exits cleanly).

Fix: Add --writable --write-dir /path/to/write-dir before the subcommand.

Failure modes

Symptom	Error	Fix
--writable omitted	Error: Export requires --writable mode	Add --writable --write-dir <dir>
Output dir already has files	Re-exports cleanly (does not fail)	Safe to re-run
Empty export (Rows: 0)	No mutations flushed to --write-dir	Write and flush mutations first
Wrong --write-dir	Empty export or IO error	Use the same --write-dir as your write operations