executor: add builtin aggregate function json_arrayagg

[arthuryangcs]

What problem does this PR solve?

• closes Call For Participation: finish the unsupported aggregate functions #7623
• closes Call For Participation: implement aggregate function JSON_ARRAYAGG #19795

What is changed and how it works?

add an json_arrayagg function

Check List

• Make sure the replace instruction is changed back to the required instruction and the version is the latest.

Tests

	tk.MustExec(`CREATE TABLE t (
		a int(11),
		b varchar(100),
		c decimal(3,2),
		d json,
		e date,
		f time,
		g datetime DEFAULT '2012-01-01',
		h timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
		i char(36),
		j text(50));`)

	tk.MustExec(`insert into t values(1, 'ab', 5.5, '{"id": 1}', '2020-01-10', '11:12:13', '2020-01-11', '0000-00-00 00:00:00', 'first', 'json_arrayagg_test');`)

	result := tk.MustQuery("select a, json_arrayagg(b) from t group by a order by a;")
	result.Check(testkit.Rows(`1 ["ab"]`))
	result = tk.MustQuery("select b, json_arrayagg(c) from t group by b order by b;")
	result.Check(testkit.Rows(`ab [5.5]`))
	result = tk.MustQuery("select e, json_arrayagg(f) from t group by e order by e;")
	result.Check(testkit.Rows(`2020-01-10 ["11:12:13"]`))
	result = tk.MustQuery("select f, json_arrayagg(g) from t group by f order by f;")
	result.Check(testkit.Rows(`11:12:13 ["2020-01-11 00:00:00"]`))
	result = tk.MustQuery("select g, json_arrayagg(h) from t group by g order by g;")
	result.Check(testkit.Rows(`2020-01-11 00:00:00 ["0000-00-00 00:00:00"]`))
	result = tk.MustQuery("select h, json_arrayagg(i) from t group by h order by h;")
	result.Check(testkit.Rows(`0000-00-00 00:00:00 ["first"]`))
	result = tk.MustQuery("select i, json_arrayagg(j) from t group by i order by i;")
	result.Check(testkit.Rows(`first ["json_arrayagg_test"]`))
	result = tk.MustQuery("select json_arrayagg(23) from t group by a order by a;")
	result.Check(testkit.Rows(`[23]`))
	result = tk.MustQuery("select json_arrayagg(null) from t group by a order by a;")
	result.Check(testkit.Rows(`[null]`))

Code changes

• Add executor/aggfuncs/func_json_arrayagg.go
• Add executor/aggfuncs/func_json_arrayagg_test.go
• Delete all srcChk.AppendDatum(0, &types.Datum{}) and the end of Chunk

Related changes

• Need to add the definition of json_objectagg in pingcap/parser

Release Note

Add builtin aggregate function `json_arrayagg`

[sre-bot]

No release note, Please follow https://github.com/pingcap/community/blob/master/contributors/release-note-checker.md

[kennytm]

depends on pingcap/parser#1020

[arthuryangcs]

@qw4990 @wshwsh12 @winoros Please review the code.

[arthuryangcs]

@qw4990 @wshwsh12 @winoros Please.

[tisonkun]

@arthuryangcs Thanks for your contribution!

You can cc @wshwsh12 to ping him. Most of our committer received many email every day so feel free to ping them when they don't repsonse.

/cc @wshwsh12

[arthuryangcs]

Done.
/cc @wshwsh12

[arthuryangcs]

PTAL
/cc @wshwsh12

[wshwsh12]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: c17cc16

[arthuryangcs]

/run-all-tests

[ti-chi-bot]

@arthuryangcs: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

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[arthuryangcs]

/run-all-tests

[zhouqiang-cl]

/rebuild