Add system.dropped_tables_parts table - second attempt #58038

yakov-olkhovskiy · 2023-12-19T15:47:34Z

Changelog category (leave one):

New Feature

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

Table system.dropped_tables_parts contains parts of system.dropped_tables tables (dropped but not yet removed tables)

Documentation entry for user-facing changes

Documentation is written (mandatory for new features)

robot-clickhouse-ci-2 · 2023-12-19T15:48:51Z

This is an automated comment for commit b05211c with description of existing statuses. It's updated for the latest CI running

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Successful checks

Check name	Description	Status
AST fuzzer	Runs randomly generated queries to catch program errors. The build type is optionally given in parenthesis. If it fails, ask a maintainer for help	✅ success
CI running	A meta-check that indicates the running CI. Normally, it's in success or pending state. The failed status indicates some problems with the PR	✅ success
ClickBench	Runs [ClickBench](https://github.com/ClickHouse/ClickBench/) with instant-attach table	✅ success
ClickHouse build check	Builds ClickHouse in various configurations for use in further steps. You have to fix the builds that fail. Build logs often has enough information to fix the error, but you might have to reproduce the failure locally. The cmake options can be found in the build log, grepping for cmake. Use these options and follow the general build process	✅ success
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Docs Check	Builds and tests the documentation	✅ success
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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Integration tests	The integration tests report. In parenthesis the package type is given, and in square brackets are the optional part/total tests	✅ success
Mergeable Check	Checks if all other necessary checks are successful	✅ success
SQLTest	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ 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
Stateless tests	Runs stateless functional tests for ClickHouse binaries built in various configurations -- release, debug, with sanitizers, etc	✅ success
Style Check	Runs a set of checks to keep the code style clean. If some of tests failed, see the related log from the report	✅ success
Unit tests	Runs the unit tests for different release types	✅ success

Check name	Description	Status
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
Stress test	Runs stateless functional tests concurrently from several clients to detect concurrency-related errors	❌ failure
Upgrade check	Runs stress tests on server version from last release and then tries to upgrade it to the version from the PR. It checks if the new server can successfully startup without any errors, crashes or sanitizer asserts	❌ failure

yakov-olkhovskiy · 2023-12-19T23:14:57Z

@antonio2368 could you please specify which stateless tests were failing after this PR?

antonio2368 · 2023-12-20T07:11:31Z

@yakov-olkhovskiy all test failed here would consistently fail with Databse ordinary
https://s3.amazonaws.com/clickhouse-test-reports/0/34ca74878eb7fbf92c8911d3abfbbd3025fabf39/stateless_tests__release__databaseordinary_.html

Seems we run with that database only on master so you couldn't have noticed that in PR.
You can test locally by specifying --db-engine Ordinary flag for clickhouse-test.
e.g. ./tests/clickhouse-test 02723_zookeeper_name --db-engine Ordinary

tavplubix · 2023-12-21T17:20:02Z

We also check that new (and midified) tests work with Ordinary database in the flaky check, but the modified 02698_marked_dropped_tables is disabled for Ordinary:

2023-12-19 18:04:13 Running about 1 stateless tests (ForkPoolWorker-2).
2023-12-19 18:04:13 
2023-12-19 18:04:13 02698_marked_dropped_tables:                                            [ SKIPPED ] 0.00 sec. - not running for current build
2023-12-19 18:04:13 
2023-12-19 18:04:13 0 tests passed. 1 tests skipped. 0.00 s elapsed (ForkPoolWorker-2).
2023-12-19 18:04:13 
2023-12-19 18:04:13 0 tests passed. 0 tests skipped. 0.00 s elapsed (MainProcess).
2023-12-19 18:04:18 Won't run stateful tests because test data wasn't loaded.

and the previous PR did not have any tests at all

tavplubix · 2023-12-21T17:24:30Z

Btw, what's the usecase for the new table?

tavplubix · 2023-12-21T17:34:35Z

src/Storages/System/StorageSystemDroppedTablesParts.cpp

+StoragesDroppedInfoStream::StoragesDroppedInfoStream(const SelectQueryInfo & query_info, ContextPtr context)
+        : StoragesInfoStreamBase(context)
+{
+    needsLock = false;


It looks ugly, however, acquiring the lock for share (especially in Atomic database, especially if the table is dropped) is almost no-op (no chance it will wait for something)

this class is common for both - dropped and alive tables - we need the way to distinct between just-dropped table for system.parts and table for system.dropped_tables_parts
but yes, it's ugly - will try to improve

tavplubix · 2023-12-21T17:36:21Z

src/Storages/System/StorageSystemPartsBase.cpp

@@ -1,3 +1,4 @@
+#include "Common/SipHash.h"


Suggested change

#include "Common/SipHash.h"

#include <Common/SipHash.h>

tavplubix · 2023-12-21T17:40:29Z

src/Storages/System/StorageSystemPartsBase.cpp

+                    UUID storage_uuid = storage->getStorageID().uuid;
+                    if (database->getEngineName() == "Ordinary")
+                    {
+                        SipHash hash;
+                        hash.update(database_name);
+                        hash.update(table_name);
+                        storage_uuid = hash.get128();


It should not display any UUIDs for tables from Ordinary databases, otherwise, it may be confusing. Also, assigning a random hash to UUID is wrong, because this UUID is likely to be invalid, see https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_(random)

we don't display this UUID - we need it only as a key for internal map - previously we used database_name+table_name pair here, but because we can delete table with the same name multiple times, it can't be used to uniquely identify such tables in dropped_tables, so I replaced this pair with table's UUID

I'm confused here, wouldn't we also get the same hash for the same database - table name pair and still have the same problem for Ordinary databases as without UUID?

@antonio2368 yes, we would, but per my knowledge Ordinary do not use postponed deletion

tavplubix · 2023-12-21T17:42:49Z

tests/queries/0_stateless/02698_marked_dropped_tables.sql

 DROP TABLE 25400_dropped_tables;

 SELECT table, engine FROM system.dropped_tables WHERE database = currentDatabase() LIMIT 1;
 DESCRIBE TABLE system.dropped_tables;
-
+SELECT database, table, name FROM system.dropped_tables_parts WHERE database = currentDatabase() and table = '25400_dropped_tables';


Let's also add a test that runs select * from system.dropped_tables_parts format Null and works in parallel with other tests

... format Null will not test the issue with Ordinary - I added a test which will...

Yes, but the purpose of this query is to find race conditions, not issues with Ordinary

yakov-olkhovskiy · 2023-12-21T18:36:37Z

Btw, what's the usecase for the new table?

After DROP TABLE parts are removed from system.parts but not yet deleted physically - the purpose of this table is to have access to info about these parts. Particularly it allows to account for difference between parts count in system.parts and metric PartsActive - it only updates when parts physically deleted.

Revert "Revert "Add system.dropped_tables_parts table""

3d8933f

yakov-olkhovskiy assigned KochetovNicolai Dec 19, 2023

robot-clickhouse-ci-2 added the pr-feature Pull request with new product feature label Dec 19, 2023

yakov-olkhovskiy added 2 commits December 19, 2023 10:51

Update 02698_marked_dropped_tables.sql

17c3212

Update 02698_marked_dropped_tables.reference

f0a20c6

fix for Ordinary

2ad9c7d

tavplubix reviewed Dec 21, 2023

View reviewed changes

StoragesInfoStreamBase refactoring, additional test, style fix

d7fe862

KochetovNicolai approved these changes Jan 8, 2024

View reviewed changes

Update 02947_dropped_tables_parts.sql

b05211c

yakov-olkhovskiy merged commit cfa41e7 into master Jan 9, 2024
262 of 265 checks passed

yakov-olkhovskiy deleted the revert-58022-revert-57555-ft-dropped_tables_parts branch January 9, 2024 05:47

yakov-olkhovskiy mentioned this pull request Jan 12, 2024

Return and fix 01600_parts_states_metrics_long test #58748

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Add system.dropped_tables_parts table - second attempt #58038

Add system.dropped_tables_parts table - second attempt #58038

yakov-olkhovskiy commented Dec 19, 2023

robot-clickhouse-ci-2 commented Dec 19, 2023 •

edited by robot-ch-test-poll4

yakov-olkhovskiy commented Dec 19, 2023

antonio2368 commented Dec 20, 2023

tavplubix commented Dec 21, 2023

tavplubix commented Dec 21, 2023

tavplubix Dec 21, 2023

yakov-olkhovskiy Dec 23, 2023

tavplubix Dec 21, 2023

tavplubix Dec 21, 2023

yakov-olkhovskiy Dec 21, 2023

antonio2368 Dec 22, 2023

yakov-olkhovskiy Dec 22, 2023

tavplubix Dec 21, 2023

yakov-olkhovskiy Dec 23, 2023

tavplubix Jan 8, 2024

yakov-olkhovskiy commented Dec 21, 2023

Add system.dropped_tables_parts table - second attempt #58038

Add system.dropped_tables_parts table - second attempt #58038

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yakov-olkhovskiy commented Dec 19, 2023

Changelog category (leave one):

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

Documentation entry for user-facing changes

robot-clickhouse-ci-2 commented Dec 19, 2023 • edited by robot-ch-test-poll4

yakov-olkhovskiy commented Dec 19, 2023

antonio2368 commented Dec 20, 2023

tavplubix commented Dec 21, 2023

tavplubix commented Dec 21, 2023

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yakov-olkhovskiy commented Dec 21, 2023

robot-clickhouse-ci-2 commented Dec 19, 2023 •

edited by robot-ch-test-poll4