MySQL binary protocol implementation for initial support of Tableau Online #54115

slvrtrn · 2023-08-31T11:43:45Z

Resolves #51103.

This PR allows connecting to Tableau Online, discovering the tables, and fetching the data.

Tableau Online wraps everything into prepared statements, even the simplest SELECTs. However, it does not add the parameters to bind - everything is hardcoded into the query. The current MySQL interface implementation was missing binary protocol implementation, as well as COM_STMT_PREPARE, COM_STMT_EXECUTE, and COM_STMT_CLOSE handlers. This PR addresses this.

Please note: the prepared statements implementation is pretty minimal, we do not support arguments binding yet, it is not required in this particular Tableau online use case. It will be implemented as a follow-up if necessary after extensive testing of Tableau Online in case we discover issues.

I also tweaked SHOW COLUMNS a bit as it did not 100% match the MySQL spec.

Corner cases of Decimal128 with precision > 65 or scale > 30 were also addressed, as this is the maximum according to the spec.

Changelog category (leave one):

Improvement

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

The MySQL interface gained a minimal implementation of prepared statements, just enough to allow a connection from Tableau Online to ClickHouse via the MySQL connector.

…ents-for-mysql

robot-ch-test-poll3 · 2023-08-31T11:47:33Z

This is an automated comment for commit 44e1f6b with description of existing statuses. It's updated for the latest CI running

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clickhouse-ci · 2023-09-01T16:08:26Z

This is an automatic comment. The PR descriptions does not match the template.

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The error is: Changelog entry required for category 'Improvement'

clickhouse-ci · 2023-09-01T16:09:40Z

This is an automatic comment. The PR descriptions does not match the template.

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The error is: Changelog entry required for category 'Improvement'

clickhouse-ci · 2023-09-01T16:15:46Z

This is an automatic comment. The PR descriptions does not match the template.

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The error is: Changelog entry required for category 'Improvement'

clickhouse-ci · 2023-09-01T16:16:07Z

This is an automatic comment. The PR descriptions does not match the template.

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The error is: Changelog entry required for category 'Improvement'

clickhouse-ci · 2023-09-01T16:21:03Z

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The error is: Changelog entry required for category 'Improvement'

src/Interpreters/InterpreterShowColumnsQuery.cpp

src/Core/MySQL/PacketsProtocolText.h

rschu1ze

Second batch of comments.

src/Core/MySQL/PacketsProtocolBinary.cpp

src/Core/MySQL/PacketsProtocolBinary.h

src/Core/MySQL/PacketsProtocolBinary.cpp

rschu1ze · 2023-09-05T20:39:28Z

src/Core/MySQL/PacketsProtocolBinary.cpp

+                        break;
+                    }
+                    case TypeIndex::UInt16: {
+                        UInt16 value = assert_cast<const ColumnVector<UInt16> &>(*col).getData()[row_num];


We are casting *col to the specific column implementation of the corresponding type (e.g. ColumnVector<UInt16>). That is okay.

But: This only works if col is not of low-cardinality (ColumnLowCardinality), or nullable (ColumnNullable), sparse (ColumnSparse) or const (ColumnConst) type. These classes are (possibly chained) wrappers around the actual column structure. In l. 164, we are stripping the low-cardinality and nullness of the datatype away, but we would need to do something equivalent for col. Check e.g. recursiveRemoveSparse() (Columns/ColumnSparse.h), etc.

LowCardinality and Nullable are removed prior to that, so I assumed it should always work as intended.

They are only removed from the data type, not from the actual data. I am pretty sure this will go boom, please try it out.

src/Core/MySQL/PacketsProtocolBinary.cpp

rschu1ze

Dumping the 3rd batch of comments. More tomorrow.

src/Core/MySQL/PacketsProtocolBinary.cpp

src/DataTypes/DataTypesDecimal.cpp

src/Server/MySQLHandler.h

src/Server/MySQLHandler.cpp

src/Storages/System/InformationSchema/schemata.sql

src/Storages/System/InformationSchema/tables.sql

tests/integration/test_mysql_protocol/prepared_statements_test.sql

…ents-for-mysql

…-statements-for-mysql' into simplified-prepared-statements-for-mysql

rschu1ze

Lgtm, thanks.

Kindly look at the remaining (mostly small) comments, we can submit afterwards.

src/Core/MySQL/PacketsProtocolBinary.h

src/Core/MySQL/PacketsProtocolBinary.cpp

src/Server/MySQLHandler.h

src/Server/MySQLHandler.cpp

rschu1ze · 2023-09-12T19:18:54Z

src/Core/MySQL/PacketsProtocolBinary.cpp

+                        break;
+                    }
+                    case TypeIndex::UInt16: {
+                        UInt16 value = assert_cast<const ColumnVector<UInt16> &>(*col).getData()[row_num];


They are only removed from the data type, not from the actual data. I am pretty sure this will go boom, please try it out.

1. Disables namespace indentation in accordance with 16. of (*) and the majority of the codebase. 2. Disables {} for single-statement if/for/while in accordance with 17. of (*) and the majority of the codebase. Note: clang-format is used manually and voluntarily, usually only on new files. Nothing is automatically reformatted, this is only about how new files look. Motivated by ClickHouse#54115 (comment). (*) https://clickhouse.com/docs/en/development/style#formatting

…ents-for-mysql

MaceWindu · 2023-10-07T18:05:35Z

Is it possible to disable this feature using CH option? It introduce several protocol violations making it unusable (I will try to fill found issues if they are not reported yet) as client library now switch to binary protocol

rschu1ze · 2023-10-07T18:20:19Z

@MaceWindu No, it is not possible to disable the binary protocol as it an integral part of the MySQL wire protocol. If you run into problems due to this PR, kindly open an issue, ideally with a small example that doesn't work.

slvrtrn added 7 commits August 8, 2023 23:48

Simplified prepared statements handling for MySQL interface

d8904ff

One more [[unlikely]]

7fdb414

WIP prepared statements

734ffd9

Merge remote-tracking branch 'origin' into simplified-prepared-statem…

055d2e3

…ents-for-mysql

WIP prepared statements

f4dd6be

Merge remote-tracking branch 'origin' into simplified-prepared-statem…

8378441

…ents-for-mysql

Binary protocol tests

8483d1c

rschu1ze self-assigned this Aug 31, 2023

robot-ch-test-poll3 added the pr-improvement Pull request with some product improvements label Aug 31, 2023

mshustov added the can be tested Allows running workflows for external contributors label Aug 31, 2023

Add DateTime64 support

4f4640e

clickhouse-ci bot added manual approve Manual approve required to run CI labels Sep 4, 2023

slvrtrn added 3 commits September 4, 2023 20:58

Revert format changes

2245a8d

Revert format changes

bb0eff9

Update tests, update imports, remove requirements

6e0a254

slvrtrn marked this pull request as ready for review September 4, 2023 19:51

slvrtrn added 2 commits September 4, 2023 22:05

Address style checks

319a51c

Try to resolve style check

9fa4850

slvrtrn commented Sep 4, 2023

View reviewed changes

src/Interpreters/InterpreterShowColumnsQuery.cpp Outdated Show resolved Hide resolved

Clear prepared statements when it's too many

eddf914

slvrtrn commented Sep 4, 2023

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src/Core/MySQL/PacketsProtocolText.h Show resolved Hide resolved

slvrtrn mentioned this pull request Sep 5, 2023

Basic prepared statements implementation for MySQL interface #53217

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rschu1ze changed the title ~~MySQL binary protocol implementation and initial Tableau online support~~ Implement the MySQL binary protocol implementation for initial support of Tableau Online Sep 5, 2023

rschu1ze reviewed Sep 5, 2023

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rschu1ze reviewed Sep 6, 2023

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slvrtrn added 4 commits September 12, 2023 10:38

Merge remote-tracking branch 'origin' into simplified-prepared-statem…

611a75a

…ents-for-mysql

Address the review comments

dddea92

Merge remote-tracking branch 'refs/remotes/origin/simplified-prepared…

28e2ebf

…-statements-for-mysql' into simplified-prepared-statements-for-mysql

Revert information_schema changes (new PR)

0a1495f

slvrtrn requested a review from rschu1ze September 12, 2023 16:47

rschu1ze approved these changes Sep 12, 2023

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rschu1ze mentioned this pull request Sep 12, 2023

clang-format: Disable namespace indentation and omit {} in if/for/while #54554

Merged

slvrtrn added 3 commits September 13, 2023 19:33

PR review

007a75c

Merge remote-tracking branch 'origin' into simplified-prepared-statem…

c0961d9

…ents-for-mysql

Fix LowCardinality/Nullable columns issues

44e1f6b

robot-clickhouse-ci-1 added the pr-status-⏳ PR with some pending statuses label Sep 13, 2023

robot-ch-test-poll added pr-status-✅ PR with only success statuses and removed pr-status-⏳ PR with some pending statuses labels Sep 13, 2023

robot-ch-test-poll2 added pr-status-⏳ PR with some pending statuses and removed pr-status-✅ PR with only success statuses labels Sep 13, 2023

robot-ch-test-poll1 added pr-status-❌ PR with some error/faliure statuses and removed pr-status-⏳ PR with some pending statuses labels Sep 13, 2023

slvrtrn requested a review from rschu1ze September 14, 2023 08:45

rschu1ze approved these changes Sep 14, 2023

View reviewed changes

rschu1ze merged commit a9ae813 into ClickHouse:master Sep 14, 2023
280 of 283 checks passed

slvrtrn changed the title ~~Implement the MySQL binary protocol implementation for initial support of Tableau Online~~ MySQL binary protocol implementation for initial support of Tableau Online Sep 15, 2023

slvrtrn mentioned this pull request Sep 19, 2023

Adjust information_schema to support Tableau Online via MySQL interface #54773

Merged

slvrtrn mentioned this pull request Oct 9, 2023

[MySQL Interface] Nullable type reported as string to client #39297

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MySQL binary protocol implementation for initial support of Tableau Online #54115

MySQL binary protocol implementation for initial support of Tableau Online #54115

slvrtrn commented Aug 31, 2023 •

edited by rschu1ze

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rschu1ze commented Oct 7, 2023

MySQL binary protocol implementation for initial support of Tableau Online #54115

MySQL binary protocol implementation for initial support of Tableau Online #54115

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slvrtrn commented Aug 31, 2023 • edited by rschu1ze

Changelog category (leave one):

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

robot-ch-test-poll3 commented Aug 31, 2023 • edited by robot-ch-test-poll2

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slvrtrn commented Aug 31, 2023 •

edited by rschu1ze

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edited by robot-ch-test-poll2