> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hotglue.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Polars Lazyframe Reader

## PLLazyFrameReader

A Lazyframe is an abstraction of a dataframe that can stream your data from your sync output, apply relevant transformations, and then writes to your export format without ever loading the entire dataset into memory.

```python theme={null}
import gluestick as gs
import polars as pl

reader = gs.PLLazyFrameReader()

TENANT_ID = "TENANT_123"

for stream in reader.input_files.keys():
    lf = reader.get(stream, catalog_types=True)
    lf = lf.with_columns(
        pl.lit(TENANT_ID).alias("tenant_id")
    )
    gs.to_export(lf, stream, "./etl-output", keys=["id"])
```