When sharding, use the where clause in the shard key to distribute requests more evenly (#2229)

Author: ericallam

apps/webapp/app/services/realtimeClient.server.ts

@@ -292,7 +292,7 @@ export class RealtimeClient {
   ): URL {
     const $url = new URL(url.toString());
 
-    const electricOrigin = this.#resolveElectricOrigin(environment.id);
+    const electricOrigin = this.#resolveElectricOrigin($url, whereClause, environment.id);
     const electricUrl = new URL(`${electricOrigin}/v1/shape`);
 
     // Copy over all the url search params to the electric url
@@ -483,14 +483,30 @@ export class RealtimeClient {
     return `${this.options.keyPrefix}:${environmentId}`;
   }
 
-  #resolveElectricOrigin(environmentId: string) {
+  #resolveElectricOrigin(url: URL, whereClause: string, environmentId: string) {
     if (typeof this.options.electricOrigin === "string") {
       return this.options.electricOrigin;
     }
 
-    const index = jumpHash(environmentId, this.options.electricOrigin.length);
+    const shardKey = this.#getShardKey(whereClause, environmentId);
 
-    return this.options.electricOrigin[index] ?? this.options.electricOrigin[0];
+    const index = jumpHash(shardKey, this.options.electricOrigin.length);
+
+    const origin = this.options.electricOrigin[index] ?? this.options.electricOrigin[0];
+
+    logger.debug("[realtimeClient] resolveElectricOrigin", {
+      whereClause,
+      environmentId,
+      shardKey,
+      index,
+      electricOrigin: origin,
+    });
+
+    return origin;
+  }
+
+  #getShardKey(whereClause: string, environmentId: string) {
+    return [environmentId, whereClause].join(":");
   }
 
   #registerCommands() {

docker/docker-compose.yml

@@ -48,7 +48,7 @@ services:
 
   electric:
     container_name: electric
-    image: electricsql/electric:1.0.13@sha256:4e69c4a6ec3e976efbdd8b7e6de427e771aeacdbc0c8c7ca22eb0ca6ab1611ff
+    image: electricsql/electric:1.0.22@sha256:1b151dc8a6fd5292fba70cbc744e25bd3a1e42db5fc89b7e479b7b939980a0e2
     restart: always
     environment:
       DATABASE_URL: postgresql://postgres:postgres@database:5432/postgres?sslmode=disable
@@ -60,6 +60,21 @@ services:
     depends_on:
       - database
 
+  electric-shard-1:
+    container_name: electric-shard-1
+    image: electricsql/electric:1.0.22@sha256:1b151dc8a6fd5292fba70cbc744e25bd3a1e42db5fc89b7e479b7b939980a0e2
+    restart: always
+    environment:
+      DATABASE_URL: postgresql://postgres:postgres@database:5432/postgres?sslmode=disable
+      ELECTRIC_INSECURE: true
+      ELECTRIC_REPLICATION_STREAM_ID: "triggershard1"
+    networks:
+      - app_network
+    ports:
+      - "3061:3000"
+    depends_on:
+      - database
+
   clickhouse:
     image: bitnami/clickhouse:latest
     container_name: clickhouse