This is the relevant transcript from the Google Webmaster Central Office-hours Hangout, as recorded on August 23, 2019. This hangout was hosted by Googlers John Mueller and Martin Splitt from Google Zürich. Onely’s CEO Bartosz Goralewicz was the invited guest.
Martin Splitt: Do you want to answer that? Or should I answer that?
John Mueller: I can hand wave.
BG: Wait, wait, wait, wait. Explain that.
MS: Right. OK, so how do I put this?
BG: So is it like heavy CSS or –
MS: No, so here’s the thing. Pretty much every website, when we see them for the first time, goes to rendering. So there’s no indexing before it hasn’t been rendered. And, there are certain heuristics, that, if we see after a while, like, oh, this page, actually, the renderer does not diff as much or doesn’t diff, it looks the way before, like, we get – so what happens –
BG: So we get a new domain –
MS: Right, we do a crawl, right, which means, yeah, let’s say you get a new domain –
BG: You learn how much CPU this new domain was –
BG: – taking –
BG: So, you look at the difference between the initial HTML, and, then, if after rendering you see extra content?
JM: Because it’s cheap for us.
MS: It’s cheap. It’s cheaper than the complexity that we infer, so, like, there’s very, very few cases, and the internals of that are very complicated, and I still haven’t fully, like, grasped what exactly triggers the heuristics –
MS: – initial crawl –
BG: – initial HTML, whatever, and then the rendered DOM.
MS: Yeah, crawled DOM and rendered DOM.
BG: OK, that’s interesting.
MS: And I wouldn’t say that two waves of indexing are dead, but it’s definitely something that –
BG: Oh, they’re definitely not.
MS: They’re absolutely not, but it’s definitely – I expect, eventually rendering, crawling and indexing will come closer together. We’re not there yet, but I know the teams are looking into it.
BG: So you would –
MS: No plans, no deadlines, no road maps to be announced yet. But –
BG: You winked twice!
Here is the whole video: