Horton

Re: [HACKERS] [PATCH] Generic type subscripting

Chapman Flack <chap@anastigmatix.net>

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From: Chapman Flack <chap@anastigmatix.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2020-12-17T21:56:29Z
Lists: pgsql-hackers 
On 12/17/20 16:47, Tom Lane wrote:
> As far as "treat as" is concerned, we already have a spelling for
> that, it's called a cast.

I find them different; XQuery was the first language I had encountered
that provides both (a cast in XQuery is spelled 'cast as', just as you'd
expect), and the idea of an explicit operation that means "I am only
asserting statically what type this will have at run time; do not ever
perform any conversion or coercion, just give me an error if I'm wrong"
seems to be a distinct and useful one.

Even if there is no available SQL spelling for that, it might still one day
be a useful expression node that could be generated in certain chosen cases.

Regards,
-Chap

Commits

  1. Throw error when assigning jsonb scalar instead of a composite object

  2. Filling array gaps during jsonb subscripting

  3. Implementation of subscripting for jsonb

  4. Allow ALTER TYPE to update an existing type's typsubscript value.

  5. Allow subscripting of hstore values.

  6. Support subscripting of arbitrary types, not only arrays.

  7. jit: Reference function pointer types via llvmjit_types.c.

  8. Teach contain_leaked_vars that assignment SubscriptingRefs are leaky.

  9. jit: Correct parameter type for generated expression evaluation functions.

  10. Renaming for new subscripting mechanism

  11. Fix assertion failure for SSL connections.

  12. Teach eval_const_expressions() to handle some more cases.