Transformations

Filter, rename, convert and sort columns before loading.

Transformations are declarative steps evaluated in order. Each step receives the output of the previous one, so the sequence you define is exactly the sequence that runs.

How steps execute

Evaluation order

raw rows
   |
   +- step 1  filter        amount > 100
   +- step 2  rename        cust_id -> customer_id
   +- step 3  convert_type  order_date -> number (epoch)
   +- step 4  sort          order_date descending
   |
   v
materialized dataset

Filter

Keeps only the rows that satisfy a comparison.

Field	Type	Description
column	string	Column to compare.
operator_type	enum	eq, neq, gt, lt, gte, lte (symbol forms ==, !=, >, <, >=, <= also accepted) plus contains, startswith and endswith for text columns.
value	string	Value to compare against.

Rename

Maps a source column name to a target name. Use it to normalise messy upstream headers into consistent snake_case.

Field	Type	Description
from	string	Existing column name.
to	string	New column name.

Convert type

Casts a column to a different data type. Values that cannot be parsed become null; the original text column is replaced in place.

Accepted converted_to values

Field	Type	Description
string	text	Text. Safe for identifiers and labels. Alias: text.
integer	whole number	64-bit integer. Aliases: number, int.
float	decimal	Double precision number. Aliases: decimal, double.
boolean	true / false	Accepts common spellings. Alias: bool.
date	timestamp	Parsed as a datetime. Alias: datetime.

Sort

Orders rows by a column, ascending or descending. Sorting is applied at the end of the chain, so it determines the default order charts receive.

Ordering matters

Rename before you filter if the filter refers to the new name. Convert before you sort so numeric columns sort numerically rather than lexicographically.

Correct ordering

[
  { "transformation_type": "convert_type", "column": "amount", "converted_to": "decimal" },
  { "transformation_type": "filter", "column": "amount", "operator_type": ">", "value": "100" },
  { "transformation_type": "sort", "column": "amount", "order": "desc" }
]

Last reviewed October 2026.