On 08/26/2014 07:51 AM, Tom Lane wrote: > My feeling about it at this point is that the apparent speed gain from > using offsets is illusory: in practically all real-world cases where there > are enough keys or array elements for it to matter, costs associated with > compression (or rather failure to compress) will dominate any savings we > get from offset-assisted lookups. I agree that the evidence for this > opinion is pretty thin ... but the evidence against it is nonexistent.
Well, I have shown one test case which shows where lengths is a net penalty. However, for that to be the case, you have to have the following conditions *all* be true: * lots of top-level keys * short values * rows which are on the borderline for TOAST * table which fits in RAM ... so that's a "special case" and if it's sub-optimal, no bigee. Also, it's not like it's an order-of-magnitude slower. Anyway, I called for feedback on by blog, and have gotten some: http://www.databasesoup.com/2014/08/the-great-jsonb-tradeoff.html -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
