https://github.com/fpopic/bigquery-schema-select
(Script) Generates SQL query that selects all fields (recursively for nested fields) from the provided BigQuery schema file.
https://github.com/fpopic/bigquery-schema-select
bigquery bigquery-schema scala sql
Last synced: 3 months ago
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(Script) Generates SQL query that selects all fields (recursively for nested fields) from the provided BigQuery schema file.
- Host: GitHub
- URL: https://github.com/fpopic/bigquery-schema-select
- Owner: fpopic
- License: apache-2.0
- Created: 2020-05-23T22:00:15.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2024-08-31T13:26:24.000Z (almost 2 years ago)
- Last Synced: 2025-05-29T15:18:29.248Z (about 1 year ago)
- Topics: bigquery, bigquery-schema, scala, sql
- Language: Scala
- Homepage:
- Size: 30.3 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# bigquery-schema-select
Generates SQL query that selects all fields (recursively for nested fields) from the provided BigQuery schema file.
### Motivation
This tool is designed to help automate the creation of **explicit BigQuery views** that act as a strict schema "contract" between different layers of a medallion architecture. Think of these views as the **Public API** for your data: they provide a stable, documented interface that shields downstream consumers from the complexities and changes of the underlying raw data.
By generating an explicit `SELECT` statement that recursively expands `RECORD` and `REPEATED RECORD` types, it ensures that your views:
- **Prevent Schema Drift**: New fields added to the underlying source table will not be exposed in the view until you explicitly update the schema and regenerate it (avoiding the pitfalls of `SELECT *`).
- **Maintain Structure**: Uses `STRUCT(...)` and `ARRAY(SELECT AS STRUCT ...)` to fully specify the output record structure and maintain array order using `WITH OFFSET`.
- **Enforce Naming Standards**: Optionally aliases camelCase fields to snake_case (using the `--use_snake_case` flag) to maintain a consistent naming convention across your data products.
- **Automate Redundancy**: Avoids the error-prone and tedious process of manually rewriting complex nested SQL for dozens or hundreds of fields.
### Prerequisites
- `jq` installed on your system.
- `bash` shell.
- `bq` (Google Cloud SDK) for direct table schema fetching.
### Installation
#### Option 1: One-liner installer (Recommended)
```shell script
curl -fsSL https://raw.githubusercontent.com/fpopic/bigquery-schema-select/master/install.sh | bash
```
#### Option 2: Homebrew
```shell script
brew tap fpopic/bigquery-schema-select https://github.com/fpopic/bigquery-schema-select
brew install bigquery-schema-select
```
### Usage
Using existing table:
```shell script
bq show --schema --format=prettyjson my_project:my_dataset.my_table | ./bin/bigquery-schema-select
```
Using JSON schema file:
```shell script
cat my_schema.json | ./bin/bigquery-schema-select
```
#### Example
Input `my_schema.json`:
```json
[
{
"name": "A",
"type": "TIMESTAMP"
},
{
"name": "B",
"type": "TIMESTAMP"
},
{
"name": "C",
"type": "RECORD",
"fields": [
{
"name": "D",
"type": "RECORD",
"fields": [
{
"name": "E",
"type": "TIMESTAMP"
},
{
"name": "F",
"type": "RECORD",
"mode": "REPEATED",
"fields": [
{
"name": "G",
"type": "STRING"
}
]
}
]
},
{
"name": "H",
"type": "TIMESTAMP"
}
]
},
{
"name": "I",
"type": "RECORD",
"fields": [
{
"name": "J",
"type": "TIMESTAMP"
},
{
"name": "K",
"type": "TIMESTAMP"
}
]
},
{
"name": "L",
"type": "RECORD",
"mode": "REPEATED",
"fields": [
{
"name": "M",
"type": "TIMESTAMP"
},
{
"name": "N",
"type": "TIMESTAMP"
},
{
"name": "O",
"type": "RECORD",
"fields": [
{
"name": "P",
"type": "TIMESTAMP"
}
]
}
]
},
{
"name": "Q",
"type": "TIMESTAMP",
"mode": "REPEATED"
},
{
"name": "date",
"type": "DATE"
}
]
```
Generates:
```sql
SELECT
A,
B,
STRUCT(
STRUCT(
C.D.E,
ARRAY(
SELECT AS STRUCT
F.G
FROM
UNNEST(C.D.F) AS F
WITH
OFFSET
ORDER BY
OFFSET
) AS F
) AS D,
C.H
) AS C,
STRUCT(
I.J,
I.K
) AS I,
ARRAY(
SELECT AS STRUCT
L.M,
L.N,
STRUCT(
L.O.P
) AS O
FROM
UNNEST(L) AS L
WITH
OFFSET
ORDER BY
OFFSET
) AS L,
Q,
`date`
```
In case you would like to use snake_case for field names use flag `--use_snake_case`:
```shell script
cat my_schema.json | ./bin/bigquery-schema-select --use_snake_case
```
### Development
Run tests:
```shell script
./run-tests.sh
```