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PostgreSQL 10 High Performance
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Explain plans are pretty complicated to read. Figuring out which portion of the plan is causing the main performance issues is not necessarily obvious. A few tools have sprung up to help with analyzing them, making it easier to identify the slow portions.
Complicated query plans can be difficult to read, with only the indentation level suggesting how nodes that fit into one another are connected. One way to help visualize complicated plans is to graph them using visual explain, a feature available in the pgAdmin III tool: http://www.pgadmin.org/.
Seeing how the nodes fit together for the more complicated structures like multilevel joins is extremely valuable for learning how they work. One useful bit of trivia for the graphic display used: when you see lines connecting nodes in the plan, their thickness is proportional to how costly that section of the plan is. You can get an idea where the parts taking a while to execute are, just by looking for the wide...