sql: fix the reporting of types in information_schema.columns

[knz]

First commits from #28944 and priors.
Forked off #28690.
Fixes #27601.
Largely addresses the concerns that led to issue #26925.

Prior to this patch, CockroachDB incorrectly placed the "input syntax"
of each SQL type in the column data_type of
information_schema.columns.

The input syntax is the one reported in SHOW COLUMNS, SHOW CREATE
TABLE and other places, and is suitable to reproduce the exact type of
at able.

In contrast, information_schema.columns.data_type is constrained by
compatibility with third party tools and PostgreSQL clients. It must
report the name of the type like PostgreSQL does, which in turn is
constrained by the SQL standard. A text column must be reported as
"text" not "string"; a decimal column as "numeric" not "decimal", a
float8 column as "double precision" not "float8", and so on.

By reporting the wrong string in that column CockroachDB is confusing
ORMs, which subsequently decide that the current on-disk type is not
the one expected by the app and then initiate a schema change (ALTER
COLUMN SET TYPE).

This patch corrects this incompatibility by introducing logic that
produces the proper information schema names for column types. This is
expected to reduce ORM complaints about insufficient support for ALTER
COLUMN SET TYPE (but will be tested/evaluated separately).

Release note (bug fix): CockroachDB now populates the data_type
column of information_schema.columns like PostgreSQL for
compatibility with 3rd party tools and ORMs.

[cockroach-teamcity]

This change is 

[BramGruneir]

Just a small nit.

Reviewed 4 of 4 files at r1, 1 of 1 files at r2, 18 of 18 files at r3, 2 of 2 files at r4, 7 of 7 files at r5.
Reviewable status: complete! 0 of 0 LGTMs obtained (and 1 stale)

---

pkg/sql/sqlbase/column_type_properties.go, line 299 at r5 (raw file):

	}

	// date, timestamp, interval, int2vector, oidvector, inet, oid, uuid

This list may rot. Rephrase it and say put in (e.g. date, timestamp, interval, )

[knz]

Reviewable status: complete! 0 of 0 LGTMs obtained (and 1 stale)

---

pkg/sql/sqlbase/column_type_properties.go, line 299 at r5 (raw file):

Previously, BramGruneir (Bram Gruneir) wrote…

This list may rot. Rephrase it and say put in (e.g. date, timestamp, interval, )

Done.

[knz]

bors r+

[craig]

Build succeeded

• GitHub CI (Cockroach)