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"Unfortunately, due to the technical challenges being more difficult than expected by the team led by EnterpriseDB programmer Robert Haas, no parallel query fea

• ddorian43 11y ago
  So the parallel-query-features help to run 1 query in parallel, while your program executes multiple queries in parallel.
  • moreoverlords 11y ago
    Hi, Yes, but there's a little more to it. 1. My understanding is that the parallel query stuff they want to add into the core of postgres is about introducing parallel algorithms for scans, sorts, etc. The advantage is that when it is working there will be an opportunity to help everyone, a) regardless of how you use postgres (psql, API, etc) and b) transparently from the user perspective. 2. par_psql on the other hand is two things. Mainly it's a cute piece of syntactic sugar for psql users that makes it trivial to run multiple queries in parallel (as you observe) but also synchronises them automatically as they end, which is important. I've also provided some guides about how to use this feature to substantially accelerate single queries without much work or refactoring. It's generally a good tool for SQL workflows that might otherwise be managed by a combination of BASH and SQL, or for situations where you have one epic-sized query that is naturally easy to parallelise. This talk I gave at FOSS4G Europe (a GIS conference) offers some hints about identifying situations where queries or workflows are trivially decomposable into parallel small queries, allowing a huge speedup: http://graemebell.net/foss4gcomo.pdf http://graemebell.net/foss4gcomo.pdf Hope this is of interest and use to you.