Export data

Goal. Move data out, for analysis elsewhere or as a portable snapshot. About two minutes.

Export one model

strata ./mydb arrow export --primitive kv --format csv ./out.csv

--primitive is which model to export: kv, json, event, vector or graph. One per file.

--format is parquet, csv or jsonl. Note what is not there: despite the command being called arrow, there is no .arrow output. Asking for one fails with invalid_argument.executor.arrow_format.

What comes out

CSV carries the value and the version facts, and says how each side is encoded:

key,key_encoding,value,value_encoding,version,timestamp
k:1,utf8,v1,utf8,3,3
k:2,utf8,v2,utf8,4,4

The _encoding columns are what make binary values survive the trip. A value that is not valid UTF-8 is marked rather than mangled.

JSON exports carry the document as a string, with its own version:

strata ./mydb arrow export --primitive json --format jsonl ./docs.jsonl

{"key":"doc:1","document":"{\"age\":36,\"name\":\"Ada\"}","version":6,"timestamp":6,"document_version":1}

Picking a format

Parquet for anything going to a data tool. It is columnar, compressed and typed: the same three keys were 1920 bytes as Parquet against 119 as CSV, which inverts on real volumes.

CSV for a spreadsheet or a quick look.

JSONL when the values are documents and you want to keep them readable.

Exporting a branch or a space

Export reads the branch and space you point it at, so a snapshot of one line of work is the ordinary flags:

strata ./mydb --branch experiment arrow export --primitive kv --format parquet ./exp.parquet

What export is not

It is not a backup. It captures one model, at one branch, as of now: no history, no other models, no branch structure. A backup is a copy of the directory. Back up a database.

Failure modes

invalid_argument.executor.arrow_format. The file extension and --format have to agree, and .arrow is not a format.

A graph export produced two files. Graphs write nodes and edges separately, and the path you give is used as a stem.

Next

Import data.