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add explain and join snippets #699

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dba0289
add explain and join snippets
morganchen12 Jul 31, 2026
fcba093
remove duplicate import
morganchen12 Jul 31, 2026
41db075
Apply suggestions from code review
morganchen12 Jul 31, 2026
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328 changes: 328 additions & 0 deletions firestore/app/src/main/java/com/google/example/firestore/DocSnippets.java
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,8 @@
import com.google.firebase.firestore.pipeline.FindNearestStage;
import com.google.firebase.firestore.pipeline.SampleStage;
import com.google.firebase.firestore.pipeline.SearchStage;
import com.google.firebase.firestore.pipeline.CollectionGroupOptions;
import com.google.firebase.firestore.pipeline.CollectionHints;
import com.google.firebase.firestore.pipeline.UnnestOptions;

import static com.google.firebase.firestore.pipeline.Expression.field;
Expand Down Expand Up @@ -4204,4 +4206,330 @@ void searchPhraseMatch() {
// [END search_phrase_match]
}

void pipelineJoinTestData() {
// [START pipeline_join_test_data]
// Load set of cities.
CollectionReference cities = db.collection("cities");

Map<String, Object> sfData = new HashMap<>();
sfData.put("name", "San Francisco");
sfData.put("state", "CA");
sfData.put("country", "USA");
cities.document("SF").set(sfData);

Map<String, Object> laData = new HashMap<>();
laData.put("name", "Los Angeles");
laData.put("state", "CA");
laData.put("country", "USA");
cities.document("LA").set(laData);

Map<String, Object> dcData = new HashMap<>();
dcData.put("name", "Washington, D.C.");
dcData.put("state", null);
dcData.put("country", "USA");
cities.document("DC").set(dcData);

Map<String, Object> tokData = new HashMap<>();
tokData.put("name", "Tokyo");
tokData.put("state", null);
tokData.put("country", "Japan");
cities.document("TOK").set(tokData);

// Load restaurants in various cities.
CollectionReference sfRestaurants = db.collection("cities").document("SF").collection("restaurants");
CollectionReference laRestaurants = db.collection("cities").document("LA").collection("restaurants");
CollectionReference dcRestaurants = db.collection("cities").document("DC").collection("restaurants");

DocumentReference rest1 = sfRestaurants.document("rest1");
Map<String, Object> rest1Data = new HashMap<>();
rest1Data.put("name", "Golden Gate Pizza");
rest1Data.put("type", "pizza");
rest1Data.put("owner_id", "Mario Rossi");
rest1.set(rest1Data);

DocumentReference rest2 = sfRestaurants.document("rest2");
Map<String, Object> rest2Data = new HashMap<>();
rest2Data.put("name", "Bay Area Burger");
rest2Data.put("type", "burger");
rest2Data.put("owner_id", "Sarah Jenkins");
rest2.set(rest2Data);

DocumentReference rest3 = sfRestaurants.document("rest3");
Map<String, Object> rest3Data = new HashMap<>();
rest3Data.put("name", "Sunset Taco");
rest3Data.put("type", "mexican");
rest3Data.put("owner_id", "Edward");
rest3.set(rest3Data);

DocumentReference rest4 = laRestaurants.document("rest4");
Map<String, Object> rest4Data = new HashMap<>();
rest4Data.put("name", "Hollywood Sushi");
rest4Data.put("type", "sushi");
rest4Data.put("owner_id", "Ken Kenji");
rest4.set(rest4Data);

DocumentReference rest5 = laRestaurants.document("rest5");
Map<String, Object> rest5Data = new HashMap<>();
rest5Data.put("name", "Venice Pizza");
rest5Data.put("type", "pizza");
rest5Data.put("owner_id", "Luigi Romano");
rest5.set(rest5Data);

DocumentReference rest6 = dcRestaurants.document("rest6");
Map<String, Object> rest6Data = new HashMap<>();
rest6Data.put("name", "Capitol Tacos");
rest6Data.put("type", "mexican");
rest6Data.put("owner_id", "Maria Garcia");
rest6.set(rest6Data);

DocumentReference rest7 = dcRestaurants.document("rest7");
Map<String, Object> rest7Data = new HashMap<>();
rest7Data.put("name", "Georgetown Coffee");
rest7Data.put("type", "cafe");
rest7Data.put("owner_id", "David Kim");
rest7.set(rest7Data);

// Load collection of reviews.
CollectionReference reviews = db.collection("reviews");

Map<String, Object> rev1 = new HashMap<>();
rev1.put("restaurant", rest1);
rev1.put("rating", 5);
rev1.put("reviewer_id", "Alice");
reviews.add(rev1);

Map<String, Object> rev2 = new HashMap<>();
rev2.put("restaurant", rest1);
rev2.put("rating", 4);
rev2.put("reviewer_id", "Bob");
reviews.add(rev2);

Map<String, Object> rev3 = new HashMap<>();
rev3.put("restaurant", rest2);
rev3.put("rating", 4);
rev3.put("reviewer_id", "Charlie");
reviews.add(rev3);

Map<String, Object> rev4 = new HashMap<>();
rev4.put("restaurant", rest3);
rev4.put("rating", 5);
rev4.put("reviewer_id", "Diana");
reviews.add(rev4);

Map<String, Object> rev5 = new HashMap<>();
rev5.put("restaurant", rest3);
rev5.put("rating", 4);
rev5.put("reviewer_id", "Edward");
reviews.add(rev5);

Map<String, Object> rev6 = new HashMap<>();
rev6.put("restaurant", rest3);
rev6.put("rating", 4);
rev6.put("reviewer_id", "Fiona");
reviews.add(rev6);

// rest4 has 0 reviews

Map<String, Object> rev7 = new HashMap<>();
rev7.put("restaurant", rest5);
rev7.put("rating", 3);
rev7.put("reviewer_id", "George");
reviews.add(rev7);

Map<String, Object> rev8 = new HashMap<>();
rev8.put("restaurant", rest6);
rev8.put("rating", 5);
rev8.put("reviewer_id", "Hannah");
reviews.add(rev8);

Map<String, Object> rev9 = new HashMap<>();
rev9.put("restaurant", rest6);
rev9.put("rating", 4);
rev9.put("reviewer_id", "Ian");
reviews.add(rev9);

Map<String, Object> rev10 = new HashMap<>();
rev10.put("restaurant", rest7);
rev10.put("rating", 5);
rev10.put("reviewer_id", "Julia");
reviews.add(rev10);
// [END pipeline_join_test_data]
}

void pipelineJoinLookup() {
// [START pipeline_join_lookup]
Task<Pipeline.Snapshot> results = db.pipeline()
.collectionGroup("reviews")
.define(field("restaurant").alias("restaurant_name"))
.addFields(
db.pipeline()
.collectionGroup("restaurants")
.where(field("__name__").equal(variable("restaurant_name")))
.select("name", "type")
.toScalarExpression()
.alias("restaurant")
)
.execute();
// [END pipeline_join_lookup]
}

void pipelineJoinArray() {
// [START pipeline_join_array]
Task<Pipeline.Snapshot> results = db.pipeline()
.collectionGroup("restaurants")
.where(field("type").equal("pizza"))
.define(field("__name__").alias("restaurant_name"))
.select(
field("name"),
db.pipeline()
.collectionGroup("reviews")
.where(field("restaurant").equal(variable("restaurant_name")))
.select("rating", "reviewer_id")
.toArrayExpression()
.alias("reviews")
)
.execute();
// [END pipeline_join_array]
}

void pipelineJoinAggregate() {
// [START pipeline_join_aggregate]
Task<Pipeline.Snapshot> results = db.pipeline()
.collectionGroup("restaurants")
.where(field("type").equal("pizza"))
.define(field("__name__").alias("restaurant_name"))
.select(
field("name"),
db.pipeline()
.collectionGroup("reviews")
.where(field("restaurant").equal(variable("restaurant_name")))
.aggregate(average("rating").alias("avg_rating"))
.toScalarExpression()
.alias("avg_rating")
)
.execute();
// [END pipeline_join_aggregate]
}

void pipelineJoinLimit() {
// [START pipeline_join_limit]
Task<Pipeline.Snapshot> results = db.pipeline()
.collectionGroup("restaurants")
.define(field("__name__").alias("restaurant_name"))
.select(
field("name"),
db.pipeline()
.collectionGroup("reviews")
.where(field("restaurant").equal(variable("restaurant_name")))
.sort(field("rating").descending())
.limit(2)
.select("rating", "reviewer_id")
.toArrayExpression()
.alias("top_reviews")
)
.execute();
// [END pipeline_join_limit]
}

void pipelineJoinSubcollection() {
// [START pipeline_join_subcollection]
Task<Pipeline.Snapshot> results = db.pipeline()
.collection("cities")
.addFields(
PipelineSource.subcollection("restaurants")
.toArrayExpression()
.length()
.alias("restaurant_count")
)
.execute();
// [END pipeline_join_subcollection]
}

void pipelineJoinMultiField() {
// [START pipeline_join_multi_field]
Task<Pipeline.Snapshot> results = db.pipeline()
.collectionGroup("restaurants")
.define(
field("owner_id").alias("owner_id"),
field("__name__").alias("__name__")
)
.where(
db.pipeline()
.collectionGroup("reviews")
.where(field("restaurant").equal(variable("__name__")))
.where(field("reviewer_id").equal(variable("owner_id")))
.aggregate(countAll().alias("c"))
.toScalarExpression()
.greaterThan(0)
)
.execute();
// [END pipeline_join_multi_field]
}

void pipelineJoinAnti() {
// [START pipeline_join_anti]
Task<Pipeline.Snapshot> results = db.pipeline()
.collectionGroup("restaurants")
.define(field("__name__").alias("restaurant_name"))
.where(
db.pipeline()
.collectionGroup("reviews")
.where(field("restaurant").equal(variable("restaurant_name")))
.aggregate(countAll().alias("review_count"))
.toScalarExpression()
.equal(0)
)
.execute();
// [END pipeline_join_anti]
}

void pipelineJoinUnnest() {
// [START pipeline_join_unnest]
Task<Pipeline.Snapshot> results = db.pipeline()
.collectionGroup("restaurants")
.where(field("type").equal("pizza"))
.define(field("__name__").alias("restaurant_name"))
.unnest(
db.pipeline()
.collectionGroup("reviews")
.where(field("restaurant").equal(variable("restaurant_name")))
.select("rating", "reviewer_id")
.toArrayExpression()
.alias("review")
)
.execute();
// [END pipeline_join_unnest]
}

void pipelineJoinUncorrelated() {
// [START pipeline_join_uncorrelated]
Task<Pipeline.Snapshot> results = db.pipeline()
.collection("reviews")
// Average review rating is 4.3
.where(
field("rating").greaterThan(
db.pipeline()
.collection("reviews")
.aggregate(average("rating").alias("avg"))
.toScalarExpression()
)
)
.select("rating", "reviewer_id")
.execute();
// [END pipeline_join_uncorrelated]
}

void pipelineForceTableScan() {
// [START pipeline_force_table_scan]
// Force Planner to only do a Full-Table Scan
Task<Pipeline.Snapshot> results = db.pipeline()
.collectionGroup(
"customers",
new CollectionGroupOptions().withHints(new CollectionHints().withForceIndex("primary"))
)
.limit(2)
.execute();
// [END pipeline_force_table_scan]
}

}
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