Hacker News new | ask | show | jobs
by malisper 3571 days ago
> but it does bring the query response time down to the same order of magnitude as the non-JSON table.

In the specific example given it might, but you will still wind up with a handful of queries that are planned wrong and are orders of magnitude slower.
1 comments
mcdee 3571 days ago
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.
link
malisper 3571 days ago
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.
link