hashes are ordered, so just use the columns_hash ivar
Apparently people were mutating this array. :'(

This reverts commit abba61e2bbe320894ba8449ebdf778a1d2af545b.
pg is the only adapter that supports the xml type, so push the method down
make the headers consistent
UTF-8 encode all keys and values in nested params hash.
you can provide uuid_generate_v4 as the default value for uuid columns
dup and set the default proc to nil rather than looping through everything
Getting Started Guide: 3.2.9 -> 4.0.0. [ci skip]

Brought up in https://github.com/rails/rails/issues/9727
Should be a symbol not string to defer the choice of layout.
[ci skip]
safely publish columns and columns hash info
hide more data in the schema cache
just access the ivars rather than rb_iv_get
oops!
bumping arel
clean up pk delclaration in `create_table`
Small typos here and there.
fix hash duping on 1.9
ask column if it is a pk
`Http::Headers` directly modifies the passed environment.

The env hash passed to `Http::Headers#new` must be in env format.
Also be aware that the passed hash is modified directly.

docs and test-cases for setting headers/env in functional tests.

Follow up to #9700.
document request simulation methods in functional tests.