sql: equip scalar expressions with telemetry

[knz]

Informs https://github.com/cockroachlabs/registration/issues/203.

This patch introduces telemetry for the following scalar expressions:

• array[...], array(...), ...[...]

  telemetry: sql.ops.array.cons, sql.ops.array.flatten,
  sql.ops.array.ind

• IFERROR(...)

  telemetry: sql.ops.iferr

• unary, binary and comparison operators;

  telemetry: sql.ops.un.<op> <type>, sql.ops.bin.<type> <op> <type>, sql.ops.cmp.<type> <op> <type>

• casts;

  telemetry: sql.ops.cast.<type>::<type>, sql.ops.cast.arrays

• built-in function applications.

  telemetry: sql.builtins.<name><signature>

For example:

> select ('{"a":{"c":"d"},"e":123}'::string::jsonb #- array['a']) - 'e';
> select * from crdb_internal.feature_usage where feature_name like '%json%';
                             feature_name                             | usage_count
+---------------------------------------------------------------------+-------------+
  sql.builtins.json_remove_path.(val: jsonb, path: string[]) -> jsonb |           1
  sql.ops.cast.text::jsonb                                            |           1
  sql.ops.bin.jsonb - text                                            |           1
(3 rows)

Release note (sql change): CockroachDB will now report usage frequency
of various SQL scalar operators in telemetry, when telemetry is
enabled, so as to guide future optimizations of query performance.

[cockroach-teamcity]

This change is 

[bobvawter]

Would it be possible to get a dump of all generated counter names, just to be able to give it a quick eyeball?

Otherwise,

Reviewed 1 of 1 files at r1, 8 of 8 files at r2.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @dt and @knz)

---

pkg/sql/sem/tree/operators.go, line 33 at r2 (raw file):

// Scalar operators will be counter as sql.ops.<kind>.<lhstype> <opname> <rhstype>.
const opCounterNameFmt = "sql.ops.%s.%s"

The constant value doesn't seem to agree with the comment above.

---

pkg/sql/sem/tree/overload.go, line 58 at r2 (raw file):

	// Counter, if non-nil, should be incremented upon successful
	// type check of expressions using this overload.
	Counter telemetry.Counter

Counter isn't exported on the other types in sem/tree, does it need to be?

[knz]

Would it be possible to get a dump of all generated counter names, just to be able to give it a quick eyeball?

It's pretty big (~1300 entries), I made a list here:
allfeatures.txt

[knz]

Reviewable status: complete! 0 of 0 LGTMs obtained (and 1 stale) (waiting on @bobvawter and @dt)

---

pkg/sql/sem/tree/operators.go, line 33 at r2 (raw file):

Previously, bobvawter (Bob Vawter) wrote…

The constant value doesn't seem to agree with the comment above.

Clarified in comment.

---

pkg/sql/sem/tree/overload.go, line 58 at r2 (raw file):

Previously, bobvawter (Bob Vawter) wrote…

Counter isn't exported on the other types in sem/tree, does it need to be?

No it doesn't. Good catch!

[knz]

TFYR!

bors r+

[craig]

Canceled (will resume)

[knz]

bors r+

[craig]

Not awaiting review

[craig]

Canceled

[knz]

bors r+

[craig]

Build succeeded

• GitHub CI (Cockroach)