I would like to share my test results with Gatsby Incremental Builds on Netlify and initiate a controversial(?) discussion.
My conclusion: Netlify does not (yet?) provides incremental build support - all speedups are due to the caching effects provided by
netlify-plugin-gatsby-cache.
Prerequisites
Let’s jump right into the details. Before starting the tests, I had to switch from yarn to npm as described here. In all tests, I made sure that netlify-plugin-gatsby-cache is installed. I split tests in two parts (1) normal build with gatsby build, (2) experimental page build with GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES=true gatsby build --log-pages.
Starter Project
Test results are based on gatsby-starter-try-ghost which provides incremental build support for Gatsby Cloud. This starter creates a Gatsby demo site with content coming from a headless Ghost CMS. Here are the results:
Results
- Build command: gatsby build
| Description | init | build | post | total (min) |
|---|---|---|---|---|
| Initial build (new cache) | 1:35 | 1:25 | 0:13 | 3:13 |
| Trigger panel (keep cache) | 0:33 | 0:35 | 0:04 | 1:12 |
| Tigger Webhook | 0:27 | 0:30 | 0:03 | 1:00 |
| CMS content edit (1 Page) | 0:28 | 0:30 | 0:05 | 1:03 |
- Build command: GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES=true gatsby build --log-pages
| Description | init | build | post | total (min) |
|---|---|---|---|---|
| Initial build (new cache) | 1:35 | 1:25 | 0:06 | 2:56 |
| Trigger panel (keep cache) | 0:26 | 0:26 | 0:03 | 0:55 |
| Tigger Webhook | 0:35 | 0:35 | 0:03 | 1:13 |
| CMS content edit (1 Page) | 0:30 | 0:32 | 0:03 | 1:05 |
Discussion
As can be inferred from this test, the init phase (everything before gatsby build) takes ~ 30 seconds. 15 seconds are due to cache re-building and the rest is for other setup-related tasks. Compared to a full build (~ 3min), the savings of ~ 2min can be attributed to the cache plugin. The experimental page build savings (which is <> Gatsby incremental builds) is not significant in this example.
So, compared to Gatsby Cloud, Netlify still looses a lot of time on the init process, and best build times are due to caching effects (a real incremental build for a CMS 1 page edit takes approx 5 seconds for this project).
