Background:
I am featuring a blog built on @YihuiXie's R package blogdown.
Problem:
When I render_site(), all source files (*.Rmd) are rendered - even  the unchanged source files are re-reendered. 
This complete re-rendering is time consuming and unnecessary (I think).
Question/ Desired Solution:
How can I prevent blogdown from re-rendering the unchanged source files? I want blogdown to render only new or changed source files.
What I have already tried:
I've read the blogdown book; Yihui seems to propose the "rebuild-all" approach.
I've read the help files for
render_site()andhugo_build(). The first one states that it will render all rmd files. In contrasthugo_build()does not knit rmd files (ie., rmd files are not compiled to md files).I've checked SO and Google, but this question seems not to have been asked before.
SessionInfo():
R version 3.4.4 (2018-03-15)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS High Sierra 10.13.4
Matrix products: default
BLAS: /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.4/Resources/lib/libRlapack.dylib
locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     
other attached packages:
[1] shiny_1.1.0
loaded via a namespace (and not attached):
 [1] Rcpp_0.12.17    rstudioapi_0.7  knitr_1.20      magrittr_1.5    RcppTOML_0.1.3  xtable_1.8-2    R6_2.2.2        rlang_0.2.0     stringr_1.3.1   tools_3.4.4     xfun_0.1       
[12] miniUI_0.1.1.1  htmltools_0.3.6 yaml_2.1.19     rprojroot_1.3-2 digest_0.6.15   bookdown_0.7    later_0.7.2     promises_1.0.1  evaluate_0.10.1 mime_0.5        rmarkdown_1.9.4
[23] blogdown_0.6    stringi_1.2.2   compiler_3.4.4  backports_1.1.2 jsonlite_1.5    httpuv_1.4.3   
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