23 Jan

Improve your Odoo PostgreSQL performance

You probably have noticed already that Odoo and PostgreSQL are installed in separate packages. That should give you the following clue:

 

The standard PostgreSQL installation is neither optimized for your hardware not for your Odoo

 

Before you move into running PostgreSQL with your Odoo and through Python-driven requests, here is a list of the things you should do to give your system a real chance to run decently:

 

PostgreSQL logging

  • Be generous with logging; it’s very low-impact on the system
  • Locations for logs are better managed by syslog.
  • Just use:

log_destination = ‘csvlog’

log_directory = ‘pg_log’

Shared_buffers

work_mem

  • Start low: 32-64MB
  • Look for ‘temporary file’ lines in logs
  • set to 2-3x the largest temp file you see
  • Can cause a huge speed-up if set properly
  • Be careful: it can use that amount of memory per query

maintenance_work_mem

  • Set to 10% of system memory, up to 1GB

effective_cache_size

  • Set to the amount of file system cache available
  • If you don’t know it, set it to 50% of the available memory

Checkpointing

  • A complete fish of dirty buffers to disk
  • Potentially a lot of I/O

Easy performance boosts

  • Don’t run anything else on your PostgreSQL server
  • If PostgreSQL is in a VM, remember all of the other VMs on the same host
  • Disable the Linux OOM killer

Stupid Database Tricks

  • Don’t put your sessions in the database
  • Avoid aonstantly-updated accumulator records.
  • Don’t put the task queues in the database
  • Don’t use the database as a filesystem
  • Don’t use frequently-locked singleton records
  • Don’t use very long-running transactions
  • Mixing transactional and data warehouse queries on the same database

One schema trick

  • If one model ha sa constantly-updated section and a rarely-updated section
  • last-seen on site field
  • cut out that field into a new model

SQL Pathologies

  • Gigantic IN clauses (a typical Django anti-pattern) are problematic
  • Unanchored text queries like ‘%this%’ run slow

Indexing

  • A good index has high selectivity on commonly-used data and will return a small number of records
  • A good infex is determined by analysis, not guessing
  • Use pg_stat_user_tables – shows sequential scans
  • Use pg_stat_index_blah

Vacuuming

  • autovacuum slowing the system down? Increase autovacuum_vacuum_cost_limit in small increments
  • If the load is periodic, do manual VACUUMing instead at low-low times
  • You must VACUUM on a regular basis
  • Analyze your vacuum
  • Collect statistics on the data to help the planner choose a good plan

On-going maintenance and monitoring

  • Keep track of disk space and system load
  • memory and I/O utilization is very handy
  • 1 minute bnts
  • check_posgres.pl at bucardo.org

2 different orientation for Backups

pg_dump

  • Easiest backup tool for PostgreSQL
  • Low impact on a running database
  • Makes a copy of the database
  • becomes impractical for large databases

Streaming replication

  • Best solution for large databases
  • Easy to set up
  • Maintains an exact logical copy of the database on a different host
  • Does not guard against application-level failures, however
  • Can be used for read-only queries
  • if you are getting query cancellations then bump up a config
  • Is all-or-nothing
  • If you need partial replication, you need to use Slony or Bucardo
  • ..warning:: partial replication is a full-time effort

WAL Archiving

  • Maintains a set of base backups and WAL segments on a remote server
  • Can be used for point-in-time recovery in case of an application (or DBA) failure
  • Slightly more complex to set up

Encodings

  • Character encoding is fixed in a database when created
  • The defaults are not what you want
  • Use UTF-8 encoding

Migrations

  • All modifications to a table take an exclusive lock on that table while the modification is being done.
  • If you add a column with a default value, the table will be rewritten
  • Migrating a big table
  • Create the column as NOT NULL
  • Add constraint later once field is populated
  • Note

Vacuum FREEZE

  • Once in a while PostgreSQL needs to scan every table
  • THis can be a very big surprise
  • Run VACUUM manually periodically

Hardware

  • Get lots of ECC RAM
  • CPU is not as vital as RAM
  • Use a RAID

Big data / Data growth