On 04/08/2014 05:57 PM, Peter Geoghegan wrote:
On Tue, Apr 8, 2014 at 2:46 PM, Tom Lane <t...@sss.pgh.pa.us> wrote:
Well, let me see if I understand the situation correctly:
* jsonb_ops supports more operators
* jsonb_hash_ops produces smaller, better-performing indexes
* jsonb_ops falls over on inputs with wide field values, but
jsonb_hash_ops does not
There might be some compelling cases for indexing existence rather
than containment, since the recheck flag isn't set there, but in
general this summary seems sound. I would say that broadly, existence
is a less useful operator than containment, and so jsonb_hash_ops is
broadly more compelling. I didn't propose changing the default due to
concerns about the POLA, but I'm happy to be told that those concerns
were out of proportion to the practical benefits of a different
default.
I tend to agree with Tom that POLA will be more violated by the default
ops class not being able to index some values.
cheers
andrew
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