问题
I have a chunk of SQL in my R Markdown / Notebook Document:
```{sql output.var = "df"}
SELECT * FROM FakeData
WHERE Date >= '2017-01-01
```
It takes literally 5 minutes to run. Is there an easy way to cache the result of the query without Knitting the document or writing the file to a CSV.
I'd perhaps like the cache to live for a couple of hours, or maybe a day (is there a way to adjust this as well?)
回答1:
If you put cache=TRUE in the chunk options and you are working in rStudio, you can select a section of code and run it directly using the green arrows in the upper right of the rMarkdown/knitr console.
{sql output.var = "df", cache=TRUE}
SELECT * FROM FakeData
WHERE Date >= '2017-01-01
Also, I tend to run a regular R script in another window with EVERYTHING I am going to use in knitR. I find that I have less issues with package availability and caching if the data is stored in the global environment.
If you do it this way, and run with cache=TRUE you will definitely be able to save the data on the first run and skip the waiting next time around.
来源：https://stackoverflow.com/questions/42284274/cache-sql-chunk-with-r-markdown-notebook-without-knitting-in-rstudio