relstorage_packer 1.0

Overview

This script works also for very large Relstorage ZODBs with several million objects. The original pack script took several days and consumed lots of RAM. So there was need to accelerate the process of packing.

This script does not consume relevant amounts of RAM, runs much faster than the original. Where the old took 3.5 days only for analysis it takes now about 6 hours. On subsequent runs it only processes changes after last run: it considers only transactions newer than last processed transaction of the prior run.

At time of writing processing 44mio objects takes initially about 3-6h depending on hardware and configuration of Postgresql.

The script creates an inverse object graph, this takes little extra space in DB.

Limitations

At time of development the critical production environment was a postgresql database running relstorage with blobs stored on a fileserver in history free mode. So this is implemented.

I’am sure its easily possible to make this work on MySQL and Oracle too. Also considering blobs inside DB is for sure possible.

I’am not sure if this way of cleanup makes sense for non-history-free mode. At least it needs a lot of love and understanding of ZODB to refactor and implement.

Contributions are welcome!

Usage

Create a configuration file. It is the same as used in classical pack script deployed with Relstorage:

<relstorage>
    create-schema false
    keep-history false
    shared-blob-dir true
    blob-dir var/blobstorage
    commit-lock-timeout 600
    <postgresql>
        dsn dbname='test_site' host='127.0.0.1' user='zodb' password='secret'
    </postgresql>
</relstorage>

After installation a script relstorage_pack is available:

Usage: relstorage_pack config_file

Fast ZODB Relstorage Packer for history free PostgreSQL

Options:
  -h, --help     show this help message and exit
  -i, --init     Removes all reference counts and starts from scratch.
  -v, --verbose  More verbose output, includes debug messages.

When running first time with your database pass --init as parameter. This drops and recreates the packing table.