backend_table_hierarchy.qmd

---
title: Backend Table Hierarchy
---

Several SQL backends support two levels of hierarchy in organizing tables
(although the levels are also used for other purposes, like data access,
billing, etc.).

Ibis uses the following terminology:

- `database`: a collection of tables
- `catalog`: a collection of databases

Below is a table with the terminology used by each backend for the two levels of
hierarchy. This is provided as a reference, note that when using Ibis, we will
use the terms `catalog` and `database` and map them onto the appropriate fields.


| Backend    | Catalog        | Database   |
|------------|----------------|------------|
| bigquery   | project        | database   |
| clickhouse |                | database   |
| datafusion | catalog        | schema     |
| druid      | dataSourceType | dataSource |
| duckdb     | database       | schema     |
| flink      | catalog        | database   |
| impala     |                | database   |
| mssql      | database       | schema     |
| mysql      |                | database   |
| oracle     |                | database   |
| pandas     |                | NA         |
| polars     |                | NA         |
| postgres   | database       | schema     |
| pyspark    |                | database   |
| risingwave | database       | schema     |
| snowflake  |                | database   |
| trino      | catalog        | schema     |