Describe VIEW for YDB CLI

[jepett0]

• views: ydb scheme describe to return view query text #9618

We want YDB CLI to return view query text on ydb scheme describe view_to_describe command.

There is no generic GRPC service that can return SchemeShard's private protobuf info to YDB CLI. Ideally, we would like to implement informational tables that contain up-to-date information about the objects in the scheme. However, this is a great undertaking and it will delay the first release of views significantly.

We have decided to add a dedicated GRPC service for views and add (for now) only the DescribeView call there. (Eventually, we would also add CreateView, AlterView and DropView calls if users asked.) This approach seems to be the currently adopted one across YDB. See the recently added replication service and object storage service which both have a single RPC in them.

[jepett0]

The output looks like this:

• basic example, the view exists

...$ ydb scheme describe v
<view> v

Query text:
select * from t

• the view does not exist

...$ ydb scheme describe vvv
Status: SCHEME_ERROR
Issues: 
<main>: Error: Path not found

• the view has captured the TablePathPrefix pragma

...$ ydb scheme describe path/to/a/folder/v
<view> v

Query text:
PRAGMA TablePathPrefix = "/Root/dedicated/path/to/a/folder";
select * from `/Root/dedicated/v`

• describe of a view in json format (note: self value is replaced with ...)

$ ydb scheme describe --format proto-json-base64 v
<view> v
{"self":{...},"query_text":"select * from t"}

[CyberROFL]

lgtm

[jepett0]

If you are wondering, all describe requests sent to tx proxy are going through both:

• scheme cache (with sync version flag) to retrieve the path's SchemeShard id
• SchemeShard to retrieve the most up-to-date info about the path

[github-actions]

⚪ 2024-10-10 06:10:16 UTC Pre-commit check linux-x86_64-relwithdebinfo for 56cafd4 has started.
⚪ 2024-10-10 06:10:27 UTC Artifacts will be uploaded here
⚪ 2024-10-10 06:13:40 UTC ya make is running...
🟡 2024-10-10 07:20:48 UTC Some tests failed, follow the links below. Going to retry failed tests...

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
79982	66024	0	1	13851	106

⚪ 2024-10-10 07:28:28 UTC ya make is running... (failed tests rerun, try 2)
🟢 2024-10-10 07:39:57 UTC Tests successful.

Test history | Ya make output | Test bloat | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
105 (only retried tests)	6	0	0	0	99

🟢 2024-10-10 07:40:04 UTC Build successful.
🟡 2024-10-10 07:40:22 UTC ydbd size 2.8 GiB changed* by +1.2 MiB, which is >= 100.0 KiB vs main: Warning

ydbd size dash	main: 0d12e54	merge: 56cafd4	diff	diff %
ydbd size	3 012 071 664 Bytes	3 013 323 880 Bytes	+1.2 MiB	+0.042%
ydbd stripped size	477 602 232 Bytes	477 743 384 Bytes	+137.8 KiB	+0.030%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}

[github-actions]

⚪ 2024-10-10 06:10:28 UTC Pre-commit check linux-x86_64-release-asan for 56cafd4 has started.
⚪ 2024-10-10 06:10:39 UTC Artifacts will be uploaded here
⚪ 2024-10-10 06:13:47 UTC ya make is running...
🟡 2024-10-10 08:01:08 UTC Some tests failed, follow the links below. This fail is not in blocking policy yet

Test history | Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED?
17141	16880	0	76	79	106

🟢 2024-10-10 08:02:49 UTC Build successful.
🔴 2024-10-10 08:03:20 UTC ydbd size 5.7 GiB changed* by +2.5 MiB, which is >= 2.0 MiB vs main: Alert

ydbd size dash	main: 0d12e54	merge: 56cafd4	diff	diff %
ydbd size	6 103 926 536 Bytes	6 106 595 832 Bytes	+2.5 MiB	+0.044%
ydbd stripped size	1 520 996 016 Bytes	1 521 537 840 Bytes	+529.1 KiB	+0.036%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}