README.md

bqs

Utility for inferring, merging and comparing BigQuery schema in Go. BigQuery provides a feature to infer schema, such as bigquery.InferSchema and schema auto detection. However, bigquery.InferSchema does not support nested struct and map. schema auto detection is not available in the Go client library. This library provides a way to infer BigQuery schema from nested Go struct and map.

Features

• Infer BigQuery schema from nested Go struct and map
• Merge BigQuery schema
• Compare BigQuery schema

Example

// Row is a map[string]any, implemented as bigquery.ValueSaver
rows := []Row{
    {
        "CreatedAt": time.Now(),
        "Name":      "Alice",
        "Preferences": map[string]any{
            "Color": "Red",
        },
    },
    {
        "CreatedAt": time.Now(),
        "Name":      "Bob",
        "Age":       30,
    },
}

var mergedSchema bigquery.Schema
for _, row := range rows {
    // If you use bigquery.InferSchema, it will fail to infer the schema of nested struct.
    schema, err := bqs.Infer(row)
    if err != nil {
        return err
    }

    // Merge the schema of each row
    mergedSchema, err = bqs.Merge(mergedSchema, schema)
    if err != nil {
        return err
    }
}

// Create a new table with the schema that is combined from all rows
newMeta := &bigquery.TableMetadata{Schema: mergedSchema}
if err := table.Create(ctx, newMeta); err != nil {
    return err
}

// Insert all rows to the created table
if err := table.Inserter().Put(ctx, rows); err != nil {
    return err
}

This will create a table with the following schema and insert the rows.

CreatedAt	Name	Age	Preferences.Color
2024-02-04 03:29:55.504942	Alice	null	Red
2024-02-04 03:29:55.504943	Bob	30	null

CLI

Install

go install github.com/m-mizutani/bqs/cmd/bqs@latest

Example

$ cat test.jsonl
{"color":"blue", "number":5, "property":{"age": 18}}
{"color":"green", "number":1, "property":{"name":"Alice"}}
$ bqs infer test.jsonl
[
 {
  "name": "color",
  "type": "STRING"
 },
 {
  "name": "number",
  "type": "FLOAT"
 },
 {
  "fields": [
   {
    "name": "name",
    "type": "STRING"
   },
   {
    "name": "age",
    "type": "FLOAT"
   }
  ],
  "name": "property",
  "type": "RECORD"
 }
]

License

Apache License 2.0