4 ms·
Interesting! MVCC mechanics aside, it's also worth remembering that work_mem is only 4MB by default [0], so large intermediate results will likely spill to disk
by refset 2y ago
Interesting! MVCC mechanics aside, it's also worth remembering that work_mem is only 4MB by default [0], so large intermediate results will likely spill to disk (e.g. external sorts for ORDER BY operations).
[0] https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-WORK-MEM https://www.postgresql.org/docs/current/runtime-config-resou...
- metanonsense 2y agoDid not see your comment until after I posted mine, but exactly this. The amount of disk io from these sort operations can be massive and very surprising.