Update faq

docs/change-log.md

@@ -1,5 +1,9 @@
 # Change Log
 
+## Release in progress
+- Minor doc updates
+- New FAQ item
+
 ## v0.1.0
 - New and more consistent docs (this website). The [previous docs](https://rapidspitt.readthedocs.io/en/latest/) are marked as beta 
 - Consolidate [configuration](../setup/configuration) instructions

docs/faq.md

@@ -192,4 +192,25 @@
     ```
 
 ???+ done "Solution"
-    Reinstall conda
+    Reinstall conda
+
+## Embedded nul in string
+
+???+ failure "Problem"
+    You get the following error when downloading sensor data:
+    ```bash
+    Error in result_fetch(res@ptr, n = n) : 
+      embedded nul in string:
+    ```
+
+???+ done "Solution"
+    This problem is due to the way `RMariaDB` handles a mismatch between data types in R and MySQL (see [this issue](https://github.com/r-dbi/RMariaDB/issues/121)). Since it seems this problem won't be handled by `RMariaDB`, you have two options:
+    
+    1. If it's only a few rows that are causing this problem, remove the the null character from the conflictive table cell.
+    2. If it's not feasible to modify your data you can try swapping `RMariaDB` with `RMySQL`. Just have in mind you might have problems connecting to modern MySQL servers running in Liunx:
+        - Add `RMySQL` to the renv environment by running the following command in a terminal open on RAPIDS root folder
+        ```bash
+        R -e 'renv::install("RMySQL")'
+        ```
+        - Go to `src/data/download_phone_data.R` and replace `library(RMariaDB)` with `library(RMySQL)`
+        - In the same file replace `dbEngine <- dbConnect(MariaDB(), default.file = "./.env", group = group)` with `dbEngine <- dbConnect(MySQL(), default.file = "./.env", group = group)`