On May 31, armand pirvu modulated:
> The idea is that I would like to avoid having an index for each key
> possibly wanted to search, but rather say have the whole record then
> search by the key and get the key value, thus having one index serving
> multiple purposes so to speak
>
First, benchmarking would be important to figure out if any proposed
indexing actually speeds up the kinds of queries you want to perform.
With the recently added parallel query features, a simpler indexing
scheme with some brute-force search might be adequate?
But, you could use a search idiom like this:
(lower(json_column::text)::json) -> lower('key') = 'value'::json
This will down-convert the case on all values and keys. The left-hand
parenthetic expression could be precomputed in an expression index to
avoid repeated case conversion. But, typical searches will still have
to scan the whole index to perform the projection and match the final
value tests on the right-hand side.
If you want to do things like substring matching on field values, you
might stick with text and using regexp matches:
(lower(json_column::text)) ~ 'valuepattern'
or more structural searches:
(lower(json_column::text)) ~ '"key": "[^"]*substring[^"]*"'
Here, the left-hand expression could be trigram indexed to help with
sparse, substring matching without a full index scan. We've had good
luck using trigram indexing with regexp matching, though I've honestly
never used it for the purpose sketched above...
Karl
