The setting allows a user to provide own deduplication semantic in Replicated*MergeTree
If provided, it's used instead of data digest to generate block ID
So, for example, by providing a unique value for the setting in each INSERT statement,
user can avoid the same inserted data being deduplicated
Inserting data within the same INSERT statement are split into blocks
according to the *insert_block_size* settings
(max_insert_block_size, min_insert_block_size_rows, min_insert_block_size_bytes).
Each block with the same INSERT statement will get an ordinal number.
The ordinal number is added to insert_deduplication_token to get block dedup token
i.e. <token>_0, <token>_1, ... Deduplication is done per block
So, to guarantee deduplication for two same INSERT queries,
dedup token and number of blocks to have to be the same
Issue: #7461
* initial commit: add setting and stub
* typo
* added test stub
* fix
* wip merging new integration test and code proto
* adding steps interpreters
* adding firstly proposed solution (moving parts etc)
* added checking zookeeper path existence
* fixing the include
* fixing and sorting includes
* fixing outdated struct
* fix the name
* added ast ptr as level of indirection
* fix ref
* updating the changes
* working on test stub
* fix iterator -> reference
* revert rocksdb submodule update
* fixed show privileges test
* updated the test stub
* replaced rand() with thread_local_rng(), updated the tests
updated the test
fixed test config path
test fix
removed error messages
fixed the test
updated the test
fixed string literal
fixed literal
typo: =
* fixed the empty replica error message
* updated the test and the code with logs
* updated the possible test cases, updated
* added the code/test milestone comments
* updated the test (added more testcases)
* replaced native assert with CH one
* individual replicas recursive delete fix
* updated the AS db.name AST
* two small logging fixes
* manually generated AST fixes
* Updated the test, added the possible algo change
* Some thoughts about optimizing the solution:
ALTER MOVE PARTITION .. TO TABLE -> move to detached/ + ALTER ... ATTACH
* fix
* Removed the replica sync in test as it's invalid
* Some test tweaks
* tmp
* Rewrote the algo by using the executeQuery instead of
hand-crafting the ASTPtr.
Two questions still active.
* tr: logging active parts
* Extracted the parts moving algo into a separate helper function
* Fixed the test data and the queries slightly
* Replaced query to system.parts to direct invocation,
started building the test that breaks on various parts.
* Added the case for tables when at least one replica is alive
* Updated the test to test replicas restoration by detaching/attaching
* Altered the test to check restoration without replica restart
* Added the tables swap in the start if the server failed last time
* Hotfix when only /replicas/replica... path was deleted
* Restore ZK paths while creating a replicated MergeTree table
* Updated the docs, fixed the algo for individual replicas restoration case
* Initial parts table storage fix, tests sync fix
* Reverted individual replica restoration to general algo
* Slightly optimised getDataParts
* Trying another solution with parts detaching
* Rewrote algo without any steps, added ON CLUSTER support
* Attaching parts from other replica on restoration
* Getting part checksums from ZK
* Removed ON CLUSTER, finished working solution
* Multiple small changes after review
* Fixing parallel test
* Supporting rewritten form on cluster
* Test fix
* Moar logging
* Using source replica as checksum provider
* improve test, remove some code from parser
* Trying solution with move to detached + forget
* Moving all parts (not only Committed) to detached
* Edited docs for RESTORE REPLICA
* Re-merging
* minor fixes
Co-authored-by: Alexander Tokmakov <avtokmakov@yandex-team.ru>
TODO (suggested by Nikolai)
1. Build query plan fro current query (inside storage::read) up to WithMergableState
2. Check, that plan is simple enough: Aggregating - Expression - Filter - ReadFromStorage (or simplier)
3. Check, that filter is the same as filter in projection, and also expression calculates the same aggregation keys as in projection
4. Return WithMergableState if projection applies
3 will be easier to do with ActionsDAG, cause it sees all functions, and dependencies are direct (but it is possible with ExpressionActions also)
Also need to figure out how prewhere works for projections, and
row_filter_policies.
wip
For now uuids are not generated at all, they are present only if the
part is updated manually (as you can see in the integration test).
The only place where they can be seen today by an end user is in
`system.parts` table. I was looking for hiding this column behind an
option but couldn't find an easy way to do that.
Likely this is also required for WAL, but need to think how not to break
compatibility.
Relates to #13574, https://github.com/ClickHouse/ClickHouse/issues/13574
Next 1: In the upcoming PR the plan is to integrate de-duplication based on
these fingerprints in the query pipeline.
Next 2: We'll enable automatic generation of uuids and come up with a
way for conditionally sending uuids when processing distributed queries
only when part movement is in progress.
