polars-submit

name	polars-submit
description	Runs Polars queries or scripts on oleander via the CLI, in local or distributed mode, and saves results to the lake catalog. Use when writing Polars jobs, choosing query vs script mode, using --save / --distributed, or wiring scan()/params/result contracts.

Polars Submit

Use this skill when running Polars on oleander from the CLI, choosing between query and script mode, or deciding whether to use distributed compute.

For shared catalog conventions such as naming and namespaces, also use lake-catalog.

CLI query mode

Use query mode for quick SQL-style exploration:

oleander polars "select * from events limit 10" \
  --table events=my_namespace.events

In query mode, pass each source table with --table. Use alias=namespace.table when the SQL should refer to a short name like events.

CLI script mode

Use script mode for idiomatic Polars logic:

oleander polars --script ./job.py \
  --param table=my_namespace.events \
  --param limit=100

Script mode is the default choice when the work is easier to express with the Polars DataFrame API than with SQL.

Script contract

oleander injects the runtime pieces for you. In script mode, these are already available:

• pl
• catalog
• scan(table)
• params

Your script must assign result to a Polars LazyFrame or DataFrame.

Good:

table = params.get("table", "default.my_table")

result = (
    scan(table)
    .filter(pl.col("value") > 0)
    .group_by("category")
    .agg(pl.len().alias("rows"))
)

Avoid:

• calling .collect() yourself
• calling .remote() yourself
• handling credentials in the script

Table identifiers

For oleander Polars examples, pass table identifiers as namespace.table strings such as default.sf_311 or analytics.daily_metrics.

• In scan(table), use namespace.table
• In --table alias=..., use namespace.table
• In --save, use namespace.table

The catalog is selected separately with --catalog and defaults to oleander.

Saving results

Use --save when the result should be written to the lake catalog:

oleander polars --script ./job.py \
  --param table=default.sf_311 \
  --save analytics.top_rows \
  --save-mode overwrite

Use overwrite when replacing the full result. Use append for incremental writes.

Distributed mode

Use distributed mode only for large workloads:

oleander polars --script ./job.py \
  --param table=default.sf_311 \
  --distributed \
  --save analytics.large_result \
  --save-mode overwrite

Distributed runs write results to the lake catalog and are better for large jobs where startup cost is worth it.

Quick guidance

• Prefer query mode for simple SQL-style reads, joins, and filters.
• Prefer script mode for reusable Polars transformations.