#2
This song is not in G major. it is in D major. We are talking about the key of the song, which is not based on scales used, chords used, or anything else; the key is the key. So it does not matter how many websites say G major; key is not a majority consensus. Even if John Mayer himself logs in here and says it's in G major, he would be wrong. The key is D major.

The scale from which he's playing the lead is not E minor, it a D scale D E F# G A B C D like a major scale with a flat seventh.

The chords go D11 to D back and forth in the main section.

D11 may be played [x][5][5][5][5][x]
and D follows as [x][5][7][7][7][x]

If you play that back and forth you will find that the D11 resolves strongly to the D major, which is clearly the key. The lead is being played with reference to the D tonic, so some version of D scale is what's being played.

Now, the reason you are thinking he's playing in E minor is probably from noticing E minor is E F# G A B C D E. Those are the same notes as the scale being used, but this is not a minor song and the lead does not sound minor.. The reason websites are thinking the song is in G major is because the key of G major has one sharp F#... G A B C D E F# G, also the same notes as the scale being used. E minor is the relative minor of G major so they have the same notes; so does the D scale being used (Mixolydian).
Quote by reverb66
I'm pretty sure the Bible requires that you play through a tube amp in Texas.
#3
OP is on the right track.

The verse is G major, and the chorus was E minor, but the chorus ends on D major.

D major to G major is a very stable relationship. If G major is the home chord (of the verses and first two solos, one which replaces a verse), D has dominant function and resolves a fifth downwards. This is a common cadence (resolution) found from the days of tonal classical music.

The song uses a lot of extended chord harmony, though, so (for example) instead of just G-B-D, there's an F# above, which makes a Gmaj7. This could trick people if they don't listen to the vocal or bass lines.

The ending part's main chord is D, though, and it never goes back to a verse (vocal or solo). It just hangs onto the final chord from the chorus and makes it the home chord. However, it's a vamp between D and Cmaj7, so it's best analyzed as D mixolydian at the end.

Edit: for clarification, G major and E minor have the same notes, but different main/home/key chord.
Edit 2: yeah, the intro and the outro are using similar idioms.
Edit 3: phone may have corrected my description of the ending vamp.
#4
The solo in the end is played over a D dominant chord (that doesn't resolve to G), so thinking D as the key center would make sense. But the rest of the song is in the key of G major.
Quote by AlanHB
Just remember that there are no boring scales, just boring players.

Gear

Bach Stradivarius 37G
Charvel So Cal
Fender Dimension Bass
Hartke HyDrive 210c
Ibanez BL70
Laney VC30
Tokai TB48
Yamaha FG720S-12
Yamaha P115
#5
Quote by MaggaraMarine
But the rest of the song is in the key of G major.

How so?
Quote by reverb66
I'm pretty sure the Bible requires that you play through a tube amp in Texas.
#6
Quote by PlusPaul
How so?

Well, Neo already explained it. The song does begin and end with a D major chord, but the verse progression is D7-Gmaj7. The intro does sound like D is the tonic. But when the Gmaj7 chord gets introduced, it definitely sounds like the tonic.

A lot of time is spent on the D dominant chord, and it always kind of begins to sound like the tonic until it resolves to Gmaj7.

Kind of reminds me of this.



The chorus emphasizes D major (dominant), but in the verse it resolves to G.
Quote by AlanHB
Just remember that there are no boring scales, just boring players.

Gear

Bach Stradivarius 37G
Charvel So Cal
Fender Dimension Bass
Hartke HyDrive 210c
Ibanez BL70
Laney VC30
Tokai TB48
Yamaha FG720S-12
Yamaha P115
#7
MaggaraMarine 
Alright, I listened to it with headphones (instead of the piezoelectric "speakers" in my laptop) to hear and you are correct. It does resolve to G and the chorus sounds better hearing it do so.
Quote by reverb66
I'm pretty sure the Bible requires that you play through a tube amp in Texas.
#8
Quote by PlusPaul
MaggaraMarine 
Alright, I listened to it with headphones (instead of the piezoelectric "speakers" in my laptop) to hear and you are correct. It does resolve to G and the chorus sounds better hearing it do so.

Yeah, when you hear the bass, it becomes pretty clear.
Quote by AlanHB
Just remember that there are no boring scales, just boring players.

Gear

Bach Stradivarius 37G
Charvel So Cal
Fender Dimension Bass
Hartke HyDrive 210c
Ibanez BL70
Laney VC30
Tokai TB48
Yamaha FG720S-12
Yamaha P115
#9
Just fixed a major typo, otherwise yeah, it's not useful to listen to limited frequencies when analyzing a whole song, whether it's treble, mid, or bass only.
#10
Been catching this thread when it pops up. I've been working on Rosie myself. It's certainly a bit unique as far as the key goes. I'm actually learning quite a bit from everyone in here.

Rosie is the first song I've been learning since coming back from my 5 year hiatus (disabled right hand). It's been challenging to the say the least. Since I'm unable to finger pick the 2 chord intro I've been having to make it work with down strumming the 2 x 8 counts that lead into the first riff. Sounds close enough for what I need.