Re: [HACKERS] Custom compression methods

Hi,

On 11/27/2017 04:52 PM, Ildus Kurbangaliev wrote:
> ...
>
> Hi. This looks like a serious bug, but I couldn't reproduce it yet.
> Did you upgrade some old database or this bug happened after 
> insertion of all data to new database? I tried using your 'archie' 
> tool to download mailing lists and insert them to database, but
> couldn't catch any errors.
> 

I can trigger it pretty reliably with these steps:
   git checkout f65d21b258085bdc8ef2cc282ab1ff12da9c595c   patch -p1 < ~/custom_compression_methods_v6.patch
./configure--enable-debug --enable-cassert \    CFLAGS="-fno-omit-frame-pointer -O0 -DRANDOMIZE_ALLOCATED_MEMORY" \
--prefix=/home/postgres/pg-compress  make -s clean && make -s -j4 install   cd contrib/   make -s clean && make -s -j4
install
   export PATH=/home/postgres/pg-compress/bin:$PATH   pg_ctl -D /mnt/raid/pg-compress init   pg_ctl -D
/mnt/raid/pg-compress-l compress.log start   createdb archie   cd ~/archie/sql/   psql archie < create.sql
 
   ~/archie/bin/load.py --workers 4 --db archie */* > load.log 2>&1


I guess the trick might be -DRANDOMIZE_ALLOCATED_MEMORY (I first tried
without it, and it seemed working fine). If that's the case, I bet there
is a palloc that should have been palloc0, or something like that.

If you still can't reproduce that, I may give you access to this machine
so that you can debug it there.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services