Normalised metallicity distribution of the 133 577 RR Lyrae stars with photometric metallicities computed with the SOS pipeline. The sources are divided into the three separate regions (all-sky, LMC, and SMC) defined in Sect. 2. Green, red, and blue histograms represent all-sky, LMC, and SMC variables, respectively. The three distributions peak at mean values of [Fe/H] = − 1.07 ± 0.63, −1.31 ± 0.62, and −1.66 ± 0.66 dex for the all-sky, LMC, and SMC variables, respectively.