Copilot commented on code in PR #40238: URL: https://github.com/apache/superset/pull/40238#discussion_r3779078490
########## docs/admin_docs/configuration/dashboard-performance.mdx: ########## @@ -0,0 +1,168 @@ +--- +title: Dashboard Performance +hide_title: true +sidebar_position: 5 +version: 1 +--- + +<!-- +Licensed to the Apache Software Foundation (ASF) under one +or more contributor license agreements. See the NOTICE file +distributed with this work for additional information +regarding copyright ownership. The ASF licenses this file +to you under the Apache License, Version 2.0 (the +"License"); you may not use this file except in compliance +with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, +software distributed under the License is distributed on an +"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +KIND, either express or implied. See the License for the +specific language governing permissions and limitations +under the License. +--> + +# Dashboard Performance + +A dashboard's perceived speed is determined by three independent things: how +many charts have to render, how many queries the backend can execute +concurrently, and how quickly the underlying data warehouse can return +results. Superset gives you levers for the first two; the third belongs to +your warehouse. This page covers the dashboard-side levers and the practical +guidance around them. + +## Is there a maximum chart count per dashboard? + +**No hard limit is enforced** — Superset has no configuration key that +caps the number of charts on a dashboard. In practice, dashboards behave +well up to a few dozen charts. Beyond that, you'll typically feel friction +on the initial load and during cross-filter / time-range updates, even with +the lazy-loading optimizations described below. + +Rough thresholds to keep in mind: + +- **Under ~25 charts**: usually no perceptible problem. +- **25–50 charts**: still fine, but you start to want tabs to break the + page into chunks the user actually looks at. +- **Over ~50 charts**: split into multiple dashboards or use tabs + aggressively. The bottleneck is rarely Superset itself — it's the + warehouse executing dozens of queries in parallel and the browser + rendering dozens of chart frames. + +These are guidelines, not guarantees. A dashboard of 100 sparkline-style +charts hitting a fast cache behaves very differently from a dashboard of +20 heavy aggregations against a cold warehouse. + +## Lazy rendering — `DASHBOARD_VIRTUALIZATION` + +Superset's dashboard layout is virtualized at the row level. Charts that +are far below the user's current scroll position are not rendered (and +therefore don't fetch data) until the user scrolls them into view, and they +are unmounted again if scrolled well past. This is on by default. Review Comment: `DASHBOARD_VIRTUALIZATION` is described as preventing off-screen charts from fetching data, but in the current implementation it mainly gates chart *rendering* (via `isInView`). Data requests can still be triggered for off-screen charts unless `DASHBOARD_VIRTUALIZATION_DEFER_DATA` is enabled (see `Chart.runQuery`). This sentence should be adjusted to avoid implying data fetch deferral by default. This issue also appears on line 86 of the same file. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
