Where does the Play Store store the apps I am currently downloading? I was downloading Facebook from the Play Store awhile ago when the phone suddenly hanged up so I forcefully shut it down by removing the battery. Now when I re-boot Facebook is no longer in the queue and I need to download it again. Now my question is, where did the Play Store temporarily store it while it was being downloaded? I fear that there's now a rogue incomplete Facebook apk file somewhere that's using up wasted space.
The Playstore app usually uses /data/local to temporarily store .apk files while downloading, then installs them from there, and finally removes the temporary download-file (which then went to /data/app). The /data/local directory should be readable by all processes (so no root needed to list its contents), as it is used as a kind of "temporary directory" for a lot of things (you might think of it as a "misnamed" /tmp directory).

This directory should be "cleaned up" on reboot1, so your issue might rather be a broken .apk in /data/app. A new install should solve this anyway. I further recommend using AppMonster Pro -- yes, the Pro version: on each install/update it grabs the .apk file of the installed/updated app and stores away a copy. So in cases like this, you could simply grab a previous version and install it over.

Just for completeness: There seem to be more such "temporary directories" on Android devices. Investigating a dump from a stock 2.2 Motorola Milestone 2, I e.g. also found /data/download. Different devices might use other directories additionally. But that should not affect your Playstore question.



1 I can only base this on one of my devices (Motorola Milestone 2, stock Android 2.2), where I extracted a Nandroid backup stored on my PC. There the init.rc file (which is called during the boot process) a.o. contains the following:

mkdir /data/local 0771 mot_tcmd shell
mkdir /data/local/tmp 0771 mot_tcmd shell
mkdir /data/local/12m 0771 mot_tcmd shell
mkdir /data/local/12m/batch 0771 mot_tcmd shell


Easy to see: the /data/local directory is created during the boot, which suggests it being empty at this point. Same is valid btw. for /data/download