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A comment on When to Avoid JSONB in a PostgreSQL Schema. Parent comment

Re:When to Avoid JSONB in a PostgreSQL Schema by mcdee on Thursday September 01, 2016 @06:14PM (#12409276)
There are two separate issues. The lack of statistics is one thing, but the use of ->> instead of @> is another. Look at https://explain.depesz.com/s/zJiT Vs https://explain.depesz.com/s/ihwk for the difference.
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Re:When to Avoid JSONB in a PostgreSQL Schema by malisper on Thursday September 01, 2016 @06:30PM (#12409355)
Your queries are executing different plans. The first one is executing a nested loop join which filters out 1,246,035,384 intermediate rows. The second one is executing a index join which doesn't filter out any intermediate rows at all. This seems like it was caused either by the scientist_labs_pkey index not being there in the first trial or just random luck due to a difference in statistics.
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