Union

Descripción

Combina los documentos de otra canalización de procesamiento con los de la canalización actual.

Sintaxis

Node.js

const results = await db.pipeline()
  .collection("cities/SF/restaurants")
  .union(db.pipeline().collection("cities/NYC/restaurants"))
  .execute();

Ejemplos de clientes

Node.js
  const results = await db.pipeline()
    .collection("cities/SF/restaurants")
    .where(eq("type", "chinese"))
    .union(db.pipeline()
      .collection("cities/NYC/restaurants")
      .where(eq("type", "italian")))
    .where(gte("rating", 4.5))
    .execute();

Web

const results = await execute(db.pipeline()
  .collection("cities/SF/restaurants")
  .where(field("type").equal("Chinese"))
  .union(db.pipeline()
    .collection("cities/NY/restaurants")
    .where(field("type").equal("Italian")))
  .where(field("rating").greaterThanOrEqual(4.5))
  .sort(field("__name__").descending())
);
test.firestore.js
Swift
let results = try await db.pipeline()
  .collection("cities/SF/restaurants")
  .where(Field("type").equal("Chinese"))
  .union(with: db.pipeline()
    .collection("cities/NY/restaurants")
    .where(Field("type").equal("Italian")))
  .where(Field("rating").greaterThanOrEqual(4.5))
  .sort([Field("__name__").descending()])
  .execute()
PipelineSnippets.swift

Kotlin

val results = db.pipeline()
    .collection("cities/SF/restaurants")
    .where(field("type").equal("Chinese"))
    .union(db.pipeline()
        .collection("cities/NY/restaurants")
        .where(field("type").equal("Italian")))
    .where(field("rating").greaterThanOrEqual(4.5))
    .sort(field("__name__").descending())
    .execute()
DocSnippets.kt

Java

Task<Pipeline.Snapshot> results = db.pipeline()
    .collection("cities/SF/restaurants")
    .where(field("type").equal("Chinese"))
    .union(db.pipeline()
        .collection("cities/NY/restaurants")
        .where(field("type").equal("Italian")))
    .where(field("rating").greaterThanOrEqual(4.5))
    .sort(field("__name__").descending())
    .execute();
DocSnippets.java
Python
from google.cloud.firestore_v1.pipeline_expressions import Field

results = (
    client.pipeline()
    .collection("cities/SF/restaurants")
    .where(Field.of("type").equal("Chinese"))
    .union(
        client.pipeline()
        .collection("cities/NY/restaurants")
        .where(Field.of("type").equal("Italian"))
    )
    .where(Field.of("rating").greater_than_or_equal(4.5))
    .sort(Field.of("__name__").descending())
    .execute()
)
firestore_pipelines.py
Java
Pipeline.Snapshot results =
    firestore
        .pipeline()
        .collection("cities/SF/restaurants")
        .where(field("type").equal("Chinese"))
        .union(
            firestore
                .pipeline()
                .collection("cities/NY/restaurants")
                .where(field("type").equal("Italian")))
        .where(field("rating").greaterThanOrEqual(4.5))
        .sort(descending(field("__name__")))
        .execute()
        .get();
PipelineSnippets.java

Comportamiento

Esta etapa ejecuta varias canalizaciones en paralelo y concatena los resultados.

Orden no determinístico de los resultados

El orden en el que se combinan los resultados entre las dos canalizaciones no es determinístico. Cualquier orden percibido es inestable y no se debe confiar en él. Se puede agregar una etapa de sort posterior si se requiere un orden estable.

Node.js
  const results = await db.pipeline()
    .collection("cities/SF/restaurants")
    .where(eq("type", "chinese"))
    .union(db.pipeline()
      .collection("cities/NYC/restaurants")
      .where(eq("type", "italian")))
    .where(gte("rating", 4.5))
    .sort(Field.of("__name__"))
    .execute();

Kotlin

val results = db.pipeline()
    .collection("cities/SF/restaurants")
    .where(field("type").equal("Chinese"))
    .union(db.pipeline()
        .collection("cities/NY/restaurants")
        .where(field("type").equal("Italian")))
    .where(field("rating").greaterThanOrEqual(4.5))
    .sort(field("__name__").descending())
    .execute()
DocSnippets.kt

Java

Task<Pipeline.Snapshot> results = db.pipeline()
    .collection("cities/SF/restaurants")
    .where(field("type").equal("Chinese"))
    .union(db.pipeline()
        .collection("cities/NY/restaurants")
        .where(field("type").equal("Italian")))
    .where(field("rating").greaterThanOrEqual(4.5))
    .sort(field("__name__").descending())
    .execute();
DocSnippets.java
Python
from google.cloud.firestore_v1.pipeline_expressions import Field

results = (
    client.pipeline()
    .collection("cities/SF/restaurants")
    .where(Field.of("type").equal("Chinese"))
    .union(
        client.pipeline()
        .collection("cities/NY/restaurants")
        .where(Field.of("type").equal("Italian"))
    )
    .where(Field.of("rating").greater_than_or_equal(4.5))
    .sort(Field.of("__name__").descending())
    .execute()
)
firestore_pipelines.py
Java
Pipeline.Snapshot results =
    firestore
        .pipeline()
        .collection("cities/SF/restaurants")
        .where(field("type").equal("Chinese"))
        .union(
            firestore
                .pipeline()
                .collection("cities/NY/restaurants")
                .where(field("type").equal("Italian")))
        .where(field("rating").greaterThanOrEqual(4.5))
        .sort(descending(field("__name__")))
        .execute()
        .get();
PipelineSnippets.java

Resultados duplicados

La etapa union no anula la duplicación de los resultados. Se puede agregar una etapa de distinct o aggregate posterior si se deben quitar los resultados duplicados.