Add new function startsWithUTF8 and endsWithUTF8 #52555

taiyang-li · 2023-07-25T07:37:05Z

Changelog category (leave one):

New Feature

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Add new function startsWithUTF8 and endsWithUTF8

 :) select startsWithUTF8('中国', '中国') 

SELECT startsWithUTF8('中国', '中国')

Query id: 8a3ade25-f55d-455e-8745-8386fb617d6c

┌─startsWithUTF8('中国', '中国')─┐
│                              1 │
└────────────────────────────────┘

1 row in set. Elapsed: 0.001 sec. 

 :) select startsWithUTF8('中国', '中')

SELECT startsWithUTF8('中国', '中')

Query id: f9656d22-d6b9-452e-b1b6-c791f297bc12

┌─startsWithUTF8('中国', '中')─┐
│                            1 │
└──────────────────────────────┘

1 row in set. Elapsed: 0.001 sec. 

 :) 
 :) select startsWithUTF8('中国', '\xe4') 

SELECT startsWithUTF8('中国', '⥩

Query id: 95b06f56-fe4a-40ff-9190-81b1591ef230

┌─startsWithUTF8('中国', '⥩─┐
│                          0 │
└────────────────────────────┘

1 row in set. Elapsed: 0.001 sec. 

 :) select endsWithUTF8('中国', '\xe4')

SELECT endsWithUTF8('中国', '⥩

Query id: 27b8105a-90cd-4b1f-a95d-ae7b3b8c0ab8

┌─endsWithUTF8('中国', '⥩─┐
│                        0 │
└──────────────────────────┘

1 row in set. Elapsed: 0.001 sec. 

 :) select endsWithUTF8('中国', '中')

SELECT endsWithUTF8('中国', '中')

Query id: 88469adf-3f9b-4203-980c-e77330cff839

┌─endsWithUTF8('中国', '中')─┐
│                          0 │
└────────────────────────────┘

1 row in set. Elapsed: 0.001 sec. 

 :) select endsWithUTF8('中国', '国')

SELECT endsWithUTF8('中国', '国')

Query id: 29c70be7-b529-43f7-b42e-5e251dfaac86

┌─endsWithUTF8('中国', '国')─┐
│                          1 │
└────────────────────────────┘

1 row in set. Elapsed: 0.001 sec.

robot-ch-test-poll4 · 2023-07-25T07:44:40Z

This is an automated comment for commit d15ae5e with description of existing statuses. It's updated for the latest CI running
The full report is available here
The overall status of the commit is 🔴 failure

Check name	Description	Status
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Compatibility check	Checks that clickhouse binary runs on distributions with old libc versions. If it fails, ask a maintainer for help	🟢 success
Docker image for servers	The check to build and optionally push the mentioned image to docker hub	🟢 success
Docs Check	Builds and tests the documentation	🟡 pending
Fast test	Normally this is the first check that is ran for a PR. It builds ClickHouse and runs most of stateless functional tests, omitting some. If it fails, further checks are not started until it is fixed. Look at the report to see which tests fail, then reproduce the failure locally as described here	🟢 success
Flaky tests	Checks if new added or modified tests are flaky by running them repeatedly, in parallel, with more randomization. Functional tests are run 100 times with address sanitizer, and additional randomization of thread scheduling. Integrational tests are run up to 10 times. If at least once a new test has failed, or was too long, this check will be red. We don't allow flaky tests, read the doc	🟢 success
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Mergeable Check	Checks if all other necessary checks are successful	🔴 failure
Performance Comparison	Measure changes in query performance. The performance test report is described in detail here. In square brackets are the optional part/total tests	🔴 failure
Push to Dockerhub	The check for building and pushing the CI related docker images to docker hub	🟢 success
SQLancer	Fuzzing tests that detect logical bugs with SQLancer tool	🟢 success
Sqllogic	Run clickhouse on the sqllogic test set against sqlite and checks that all statements are passed	🟢 success
Stateful tests	Runs stateful functional tests for ClickHouse binaries built in various configurations -- release, debug, with sanitizers, etc	🟢 success
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Avogar · 2023-07-25T10:45:47Z

Can you please share the motivation to have these functions?

taiyang-li · 2023-07-25T11:48:24Z

Can you please share the motivation to have these functions?

Yes of course. When string contains UTF8 characters, current function startsWith and endsWith is not enough to handle this case, because they are processing by bytes instead of characters. So I added startsWithUTF8 and endsWithUTF8 functions, just like other functions like substring and substringUTF8

taiyang-li · 2023-07-25T11:49:56Z

BTW, can you also review this pr #51472, it had been blocked a little long.

Avogar · 2023-07-25T12:19:13Z

BTW, can you also review this pr #51472, it had been blocked a little long.

Let me first ask Yakov in DM to continue review.

UPD: he will check the PR today

src/Functions/endsWithUTF8.cpp

alexey-milovidov · 2023-07-25T22:13:13Z

I've run your test with startsWith/endsWith, and the only difference to startsWithUTF8/endsWithUTF8 is in the cases where the result is documented as undefined:

milovidov@milovidov-desktop:~/work/ClickHouse$ clickhouse-local -n
ClickHouse local version 23.7.1.1.

milovidov-desktop :) select startsWith('富强民主文明和谐', '富强');
select startsWith('富强民主文明和谐', '\xe5');
select startsWith('富强民主文明和谐', '');

SELECT startsWith('123', '123');
SELECT startsWith('123', '12');
SELECT startsWith('123', '1234');
SELECT startsWith('123', '');

select endsWith('富强民主文明和谐', '和谐');
select endsWith('富强民主文明和谐', '\x90');
select endsWith('富强民主文明和谐', '');

SELECT endsWith('123', '3');
SELECT endsWith('123', '23');
SELECT endsWith('123', '32');
SELECT endsWith('123', '');

SELECT startsWith('富强民主文明和谐', '富强')

Query id: 81b491c8-919c-431a-a71d-9adb50f2fc31

┌─startsWith('富强民主文明和谐', '富强')─┐
│                                      1 │
└────────────────────────────────────────┘

1 row in set. Elapsed: 0.001 sec. 


SELECT startsWith('富强民主文明和谐', '�')

Query id: 20b97e86-2a7e-40ae-8114-202afa0ca7c0

┌─startsWith('富强民主文明和谐', '�')─┐
│                                  1 │
└────────────────────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT startsWith('富强民主文明和谐', '')

Query id: b1bfc3d7-9924-4ee2-873d-622785fc0b90

┌─startsWith('富强民主文明和谐', '')─┐
│                                  1 │
└────────────────────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT startsWith('123', '123')

Query id: c4b67995-ca2a-405a-a6d8-3f85aaf6b974

┌─startsWith('123', '123')─┐
│                        1 │
└──────────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT startsWith('123', '12')

Query id: ff96daa9-a8cd-497d-9535-ee9f8f0e2b04

┌─startsWith('123', '12')─┐
│                       1 │
└─────────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT startsWith('123', '1234')

Query id: a50ae898-d8d6-45d0-837b-b83706b685f6

┌─startsWith('123', '1234')─┐
│                         0 │
└───────────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT startsWith('123', '')

Query id: b86f6905-096a-4334-88fb-69b03661f2a0

┌─startsWith('123', '')─┐
│                     1 │
└───────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT endsWith('富强民主文明和谐', '和谐')

Query id: cbe60202-4015-4c83-b204-8bc6710f9cf6

┌─endsWith('富强民主文明和谐', '和谐')─┐
│                                    1 │
└──────────────────────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT endsWith('富强民主文明和谐', '�')

Query id: 512e52bd-4706-44af-ae65-b8832bda14ad

┌─endsWith('富强民主文明和谐', '�')─┐
│                                1 │
└──────────────────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT endsWith('富强民主文明和谐', '')

Query id: 57af6c52-c169-4d95-9043-c53497db606d

┌─endsWith('富强民主文明和谐', '')─┐
│                                1 │
└──────────────────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT endsWith('123', '3')

Query id: 8829b817-b359-4cd5-9ef2-bb3275690150

┌─endsWith('123', '3')─┐
│                    1 │
└──────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT endsWith('123', '23')

Query id: b8a1b4c8-ad21-4871-ad92-0c749e4b3011

┌─endsWith('123', '23')─┐
│                     1 │
└───────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT endsWith('123', '32')

Query id: d802bf37-b326-4741-9c45-6748d1bfb2f8

┌─endsWith('123', '32')─┐
│                     0 │
└───────────────────────┘

1 row in set. Elapsed: 0.000 sec. 


SELECT endsWith('123', '')

Query id: d5c42529-6c43-4bb0-a137-266520ff894e

┌─endsWith('123', '')─┐
│                   1 │
└─────────────────────┘

1 row in set. Elapsed: 0.000 sec. 

milovidov-desktop :)

It means no logical difference, and the motivation of these functions remains unclear.

I cannot imagine a case where there will be a difference.

taiyang-li · 2023-07-26T02:00:17Z

startsWith matchs two strings by byte, but startsWithUTF8 match two strings by UTF8 character, that's the difference, which is also the difference between substring and substringUTF8 or any other functions with or without UTF8 suffix

 :) select startsWith('富强民主文明和谐', '\xe5');

SELECT startsWith('富强民主文明和谐', '㥩

Query id: 5c0b30b1-877b-443b-b427-6fb48ac017d5

┌─startsWith('富强民主文明和谐', '㥩─┐
│                                  1 │
└────────────────────────────────────┘

1 row in set. Elapsed: 0.014 sec. 

 :) select startsWithUTF8('富强民主文明和谐', '\xe5');
SELECT startsWithUTF8('富强民主文明和谐', '㥩

Query id: f522aa30-a747-459e-b5ac-c91169f2a4a5

┌─startsWithUTF8('富强民主文明和谐', '㥩─┐
│                                      0 │
└────────────────────────────────────────┘

1 row in set. Elapsed: 0.001 sec.

alexey-milovidov · 2023-07-26T02:30:35Z

@taiyang-li but you state in the docs that this particular case is undefined behavior.

alexey-milovidov · 2023-07-26T02:31:26Z

substring and substringUTF8 differ in the way how they treat positions inside a string; the first uses byte numbers and the second - code point numbers.

alexey-milovidov · 2023-07-26T02:34:05Z

But startsWith/endsWith don't deal with positions, and every Unicode code point is unambiguously represented by a sequence of bytes in UTF-8, assuming UTF-8 is valid*, so there is no difference.

* there is "overlong encoding" and "CESU-8" as variants of invalid UTF-8, but we don't care.

taiyang-li · 2023-07-26T02:42:57Z

@alexey-milovidov I see. What I originally want to solve is below issue. I expect startsWithUTF8 match two strings by characters instead of bytes. The assumptions in the doc are wrong. I'll fix it.

select startsWith('富强民主文明和谐', '\xe5'); 

┌─startsWith('富强民主文明和谐', '㥩─┐
│                                  1 │
└────────────────────────────────────┘

docs/en/sql-reference/functions/string-functions.md

…ickHouse into starts_ends_with_utf8

taiyang-li · 2023-08-09T07:53:40Z

@Avogar I don't know how to solve those failed tests, do you have any ideas?

Avogar · 2023-08-10T11:18:08Z

Let's merge it, failed tests is not related and I will investigate it later

taiyang-li added 2 commits July 25, 2023 15:34

add new function startsWithUTF8 and endsWithUTF8

a5d7391

fix code style

acb33c1

robot-ch-test-poll4 added the pr-feature Pull request with new product feature label Jul 25, 2023

Avogar self-assigned this Jul 25, 2023

Avogar reviewed Jul 25, 2023

View reviewed changes

src/Functions/endsWithUTF8.cpp Outdated Show resolved Hide resolved

fix code style

23897b8

taiyang-li added 3 commits July 26, 2023 10:53

change as requested

27f3c5c

fix spell

d83eabc

Merge branch 'master' into starts_ends_with_utf8

d0c9425

Avogar reviewed Jul 28, 2023

View reviewed changes

docs/en/sql-reference/functions/string-functions.md Show resolved Hide resolved

taiyang-li added 2 commits July 31, 2023 12:07

change as request

fdfe64f

Merge branch 'starts_ends_with_utf8' of https://github.com/bigo-sg/Cl…

292d2ec

…ickHouse into starts_ends_with_utf8

taiyang-li mentioned this pull request Aug 1, 2023

[CH] clickhouse startsWith and endsWith function support utf8 version apache/incubator-gluten#2436

Closed

Avogar approved these changes Aug 1, 2023

View reviewed changes

taiyang-li added 2 commits August 2, 2023 10:29

Merge branch 'master' into starts_ends_with_utf8

041af68

Merge branch 'master' into starts_ends_with_utf8

d15ae5e

Avogar merged commit 14aad35 into ClickHouse:master Aug 10, 2023
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Add new function startsWithUTF8 and endsWithUTF8 #52555

Add new function startsWithUTF8 and endsWithUTF8 #52555

taiyang-li commented Jul 25, 2023

robot-ch-test-poll4 commented Jul 25, 2023 •

edited by robot-ch-test-poll

Avogar commented Jul 25, 2023

taiyang-li commented Jul 25, 2023

taiyang-li commented Jul 25, 2023

Avogar commented Jul 25, 2023 •

edited

alexey-milovidov commented Jul 25, 2023

taiyang-li commented Jul 26, 2023 •

edited

alexey-milovidov commented Jul 26, 2023

alexey-milovidov commented Jul 26, 2023 •

edited

alexey-milovidov commented Jul 26, 2023

taiyang-li commented Jul 26, 2023 •

edited

taiyang-li commented Aug 9, 2023 •

edited

Avogar commented Aug 10, 2023

Add new function startsWithUTF8 and endsWithUTF8 #52555

Add new function startsWithUTF8 and endsWithUTF8 #52555

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taiyang-li commented Jul 25, 2023

Changelog category (leave one):

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

robot-ch-test-poll4 commented Jul 25, 2023 • edited by robot-ch-test-poll

Avogar commented Jul 25, 2023

taiyang-li commented Jul 25, 2023

taiyang-li commented Jul 25, 2023

Avogar commented Jul 25, 2023 • edited

alexey-milovidov commented Jul 25, 2023

taiyang-li commented Jul 26, 2023 • edited

alexey-milovidov commented Jul 26, 2023

alexey-milovidov commented Jul 26, 2023 • edited

alexey-milovidov commented Jul 26, 2023

taiyang-li commented Jul 26, 2023 • edited

taiyang-li commented Aug 9, 2023 • edited

Avogar commented Aug 10, 2023

robot-ch-test-poll4 commented Jul 25, 2023 •

edited by robot-ch-test-poll

Avogar commented Jul 25, 2023 •

edited

taiyang-li commented Jul 26, 2023 •

edited

alexey-milovidov commented Jul 26, 2023 •

edited

taiyang-li commented Jul 26, 2023 •

edited

taiyang-li commented Aug 9, 2023 •

edited