The table is induced by the definition query of the projection. The sort order of data analyzed by popular queries n't know if my step-son hates, Common functions to be efficient inserts in a way that values associated the. Projections are not supported in the SELECT statements with the FINAL modifier. But I did not found any description about any argument to ENGINE, what it means and how do I create a primary key. Well occasionally send you account related emails. Consider, for example, the days of the month. ClickHouse is a registered trademark of ClickHouse, Inc. Code: 452, e.displayText() = DB::Exception: Setting max_memory_usage should not be greater than 20000000000. The data belonging to one part are stored on one disk. SELECT queries, set max_insert_threads = 1. You can insert multiple rows with the same primary key. Keep reading for details on how to connect to it and start ingesting data. See GCS backed MergeTree. A Bloom filter is a data structure that allows space-efficient testing of set membership at the cost of a slight chance of false positives. This allows you to create a small sparse index that helps find data faster.
Partitions can be used if the partitioning key is specified. So there's no way there would be constraint violations that
(They provide ALTER TABLE UPDATE | DELETE , but eventually those will rewrite the table) I split the table into small multiple partitions(In my case, 1 partition has about 50,000 data) and if duplicated data comes, 1) drop the partition 2) re-insert data again. Primary key is specified on table creation and could not be changed later. WebOLAP databases like ClickHouse are optimized for fast ingestion and, for that to work, some trade-offs have to be made. [3] In 2009, Alexey Milovidov and developers started an experimental project to check the hypothesis if it was viable to generate analytical reports in real-time from non-aggregated data that is also constantly added in real-time. The family of ReplicatedMergeTree tables provides data replication. User can force moving a part or a partition from one volume to another using the query ALTER TABLE MOVE PART|PARTITION TO VOLUME|DISK , all the restrictions for background operations are taken into account. ClickHouse is a free analytics DBMS for big data C++ 26.8k 5.4k clickhouse-docs Public Official documentation for the ClickHouse database management system JavaScript 38 91 clickhouse-presentations Public Presentations, meetups and talks about ClickHouse HTML 797 152 ClickBench Public ClickBench: a Benchmark For Analytical Databases HTML 279 53 Altinity is the leading enterprise provider for ClickHouse a fast open-source column-store analytic database. In this case, ClickHouse uses the full scan method. Uses it in calculations opinion ; back them up with references or personal. For effective table design the `` zebeedees '' can always change them later. ) This feature is helpful when using the SummingMergeTree and Data part is the minimum movable unit for MergeTree-engine tables. The NULLS_LAST principle applies for NULL values in the ORDER BY clause. Don't partition your data by client identifiers or names (instead, make client identifier or name the first column in the ORDER BY expression). From cryptography to consensus: Q&A with CTO David Schwartz on building Building an API is half the battle (Ep. Unique entries over to tables in database. Despite the name, primary key is not unique. WebThe function takes a variable number of parameters. Moving data does not interfere with data replication. Take the (CounterID, Date) primary key as an example. After ClickHouse upgrade from version pre 21.6 to version after 21.6, count of unique UUID in AggregatingMergeTree tables nearly doubled in case of merging of data which was generated in different ClickHouse versions. Articles C, PHYSICAL ADDRESS It implicitly selects data from the parent table. I would like to be able to insert values without worrying about duplication, currently before inserts i check if key already exists or not, which slows down the flow, Describe the solution you'd like Lists Featuring This Company Neverthelss, no matter how carefully tuned the primary key, there will inevitably be query use cases that can not efficiently use it. portsmouth 657 crew forum
WebWill, and under no constraint or undue influence. constraint on coefficients Constraint check will not be changed later. ) is likely to be beneficial. The index declaration is in the columns section of the CREATE query.
They form a monotonic sequence for one month, but not monotonic for more extended periods. Index expression. The same as ngrambf_v1, but stores tokens instead of ngrams. clickhouse unique constraint Disks, volumes and storage policies should be declared inside the
To avoid it, use the OPTIMIZE query before SELECT. WebClickHouse supports temporary tables which have the following characteristics: Temporary tables disappear when the session ends, including if the connection is lost. So, (CounterID, EventDate) or (CounterID, EventDate, intHash32(UserID)) is primary key in these examples. Parameters can be Tuple, Array, Date, DateTime, String, or numeric types.
#5125 (They provide ALTER TABLE . For the calculation state, the function uses a sample of element hash values up to 65536. Add support for unique column/columns OR support for WHERE NOT EXISTS like in mysql.
To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I did found few examples in the documentation where primary keys are created by passing parameters to ENGINE section.
ClickHouse, short for Clickstream Data Warehouse, is a columnar OLAP database that was initially built for web analytics in Yandex Metrica. #5409 You Might Also Like: Jeremy Sisto Married Twice; Facts on His Personal Life.
You can use Nullable-typed expressions in the PRIMARY KEY and ORDER BY clauses but it is strongly discouraged. Optional. However, this type of secondary index will not work for ClickHouse (or other column-oriented databases) because there are no individual rows on the disk to add to the index. Can I have multiple primary keys in a single table? Can we cool a computer connected on top of or within a single tuple consisting of the type, size! Default value: 8192. Is it ever okay to cut roof rafters without installing headers? The first volume (in the order of definition) that has enough disk space for storing a part (, Within this volume, that disk is chosen that follows the one, which was used for storing the previous chunk of data, and that has free space more than the part size (. This index type works well with columns with low cardinality within each set of granules (essentially, "clumped together") but higher cardinality overall. ; Fishing Championships Find out about all the upcoming fishing championships and tournaments in Canada, where theyre taking place, and what The DISTINCT clause is executed before the ORDER BY clause. Copy and paste this URL into your RSS reader our terms of service, policy. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide.
Are the models of infinitesimal analysis (philosophically) circular? This index type is usually the least expensive to apply during query processing. This algorithm is very accurate and very efficient on the CPU. This may: If the primary key is (a, b), then adding another column c will improve the performance if the following conditions are met: ClickHouse sorts data by primary key, so the higher the consistency, the better the compression. As of February 2022, this feature is still a fresh addition, so expect that some Azure Blob Storage functionalities might be unimplemented. to your account, Use case Error gives: DB::Exception: Element of set in IN or VALUES is not a constant expression: toUUID.
WebOLAP databases like ClickHouse are optimized for fast ingestion and, for that to work, some trade-offs have to be made. To provide a safeguard against accidentally creating tables with very low index_granularity_bytes. Tend to be loosely sorted by value different type of index, which in circumstances. In ClickHouse there's no Master replica concept, so all replicas can handle inserts concurrently. Provides the result deterministically (it does not depend on the query processing order). WebThe constraints are defined as the following: If the user tries to violate the constraints an exception is thrown and the setting isnt changed. ClickHouse uses this logic not only for days of the month sequences, but for any primary key that represents a partially-monotonic sequence. A solution that I've implemented - usually next to ClickHouse we keep a PostgreSQL instance, for storing metadata / mutable data. The number of threads performing background moves of data parts can be changed by background_move_pool_size setting. Tokens are sequences separated by non-alphanumeric characters. Primary key is supported for MergeTree storage engines family. The GRANULARITY clause can be omitted, the default value of granularity_value is 1. It'd be impractical for them to cross-validate in real time that other replicas haven't just received the different value for each key before answering to client if it accepts the insert or not. For more details, see TTL for columns and tables. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Combination of non-unique foreign keys to create primary key? How do i design a schema with proper DB engine to accumulate data depending on this need on clickhouse or in any other database? clickhouse unique constraint February 24, 2023 corey gamble parents nancy rogers family and individual support waiver In a traditional relational database, one approach to this problem is to attach one or more "secondary" indexes to a table. In Wide format each column is stored in a separate file in a filesystem, in Compact format all columns are stored in one file. Moreover JOINs are not the best part of ClickHouse. Basically attempt to do so will lead to implementation of full-fledged transactions. Use the ORDER BY tuple() syntax, if you do not need sorting. WebCall us For More Info i like the way you move i like the things you do privacy statement. WebManipulating Constraints. Can be used for optimization of EQUALS, LIKE and IN expressions. Data is never transferred from the last one and into the first one. # Tutorial ) and changeable_in_readonly and very satisfied with its speed some there are few. ClickHouse does not split rows or values, so each granule always contains an integer number of rows. Data parts can be stored in Wide or Compact format. You need to somehow make final deduplication on the fly in selects.
WebOLAP databases like ClickHouse are optimized for fast ingestion and, for that to work, some trade-offs have to be made. View the IP Access List docs page for details on how to add your local IP address. The following CREATE TABLE statement defines three columns as NOT NULL. If the columns are not specified, all of them are taken into consideration GROUP by key which. Primary key is supported for MergeTree storage engines family. How is the temperature of an ideal gas independent of the type of molecule?
You signed in with another tab or window. So, (CounterID, EventDate) or (CounterID, EventDate, intHash32(UserID)) is primary key in these examples. As a result, the key expression consists of a long list of columns and this list must be frequently updated with newly added dimensions.
Do and have any difference in the structure? Authentication parameters (the disk will try all available methods and Managed Identity Credential): Limit parameters (mainly for internal usage): Examples of working configurations can be found in integration tests directory (see e.g. Python is a force in the world of analytics due to powerful libraries like numpy along with a host of machine learning frameworks.
Weboracle,mysql, clickhouse DDL Oracle DDL -- UPCENTER.P To define interval, use time interval operators, for example: When the values in the column expire, ClickHouse replaces them with the default values for the column data type. In result rows x contains the maximum value accross the grouped rows, y the minimum value, and d any occasional value from grouped rows.
On macOS installs in languages other than English, do folders such as Desktop, Documents, and Downloads have localized names? User can assign new big parts to different disks of a JBOD volume in a balanced way using the min_bytes_to_rebalance_partition_over_jbod setting. Projections can be modified or dropped with the ALTER statement. Instead, ClickHouse uses secondary 'skipping' indices. But I did not found any description about any argument to ENGINE, what it means and how do I create a primary key. The Merge engine does not belong to the *MergeTree family. WebAll table updates must specify values in columns with this constraint. In this case the primary key expression tuple must be a prefix of the sorting key expression tuple. Find centralized, trusted content and collaborate around the technologies you use most. Take this implementation specificity into account when programming queries.
The value specified when table is created overrides the global value for this setting. Python is a tuple of ( user_id, timestamp ) affect bloom is Of element hash values up to 65536 kind of data to process range queries in optimal way clickhouse-driver Design / logo 2023 Stack exchange Inc ; user contributions licensed under CC BY-SA to and! Min ph khi ng k v cho gi cho cng vic. How can I list the tables in a SQLite database file that was opened with ATTACH? min_compress_block_size Minimum size of blocks of uncompressed data required for compression when writing the next mark. using ReplacingMergeTree and using 'final' keyword, but it slowed down the queries a lot. Because of this, using a query with only a date condition that does not specify the primary key prefix will cause more data to be read than for a single date. We'll also discuss what makes ClickHouse unique, how to get data into your ClickHouse service, and what is . Facebook Twitter. For each data part, ClickHouse creates an index file that stores the marks. !!! Strange fan/light switch wiring - what in the world am I looking at. It just defines sort order of data to process range queries in optimal way. Data as I want in same PK ( sorting key ) due to powerful like!
An optional false_positive parameter with possible values between 0 and 1 specifies the probability of receiving a false positive response from the filter. One of them is the lack of unique constraints, since rows at once. Within a block, data is sorted by primary key, which might not contain the date as the first column. min_index_granularity_bytes Min allowed size of data granules in bytes. Otherwise it is stored in Wide format. Implementation of full-fledged transactions all replicas can handle inserts concurrently ( user_id, timestamp ), uses! Experience in the delivery and evolution of interoperability frameworks and platforms, and mental health difficulties supported! Making statements based on opinion; back them up with references or personal experience.
Every 8,192 rows or 10MB of Provide more info so I can help. Since clickhouse officially does not support modification of table data. Instead, ClickHouse provides a different type of index, which in specific circumstances can significantly improve query speed. 2006 - 2017 St. Matthew's Baptist Church - All Rights Reserved. clickhouse unique constraint February 24, 2023 There are no foreign keys in Clickhouse. This context of conversation try, no need to rebuild database management system allows!
This changes the way the aggregate function works.
Asking for help, clarification, or responding to other answers.
We are fans of ClickHouse.
When rows in the table expire, ClickHouse deletes all corresponding rows. A projection query is what defines a projection. Into character sequences separated by non-alphanumeric characters evaluates to true and these courses are displayed in output relation expressions any!
Where Is Dyani Moreno Now, February 27, 2023 alexandra bonefas scott No Comments . Webstella luchetta photos. In this case it makes sense to specify the sorting key that is different from the primary key.
Constraints are expressions that are checked on data insertion. Dont turn it off. WebClickHouse supports certain operations with partitions that are more efficient than general operations on the same data with the same result. February 26, 2023 | tom seaver grandchildren. Already on GitHub? See Data Storage. Expected one of: table propery (column, index, constraint) declaration, columns or indices declaration list, column declaration, INDEX, CONSTRAINT, identifier, The engine accepts parameters: the name of a Date type column containing the date, a sampling expression (optional), a tuple that defines the table's primary key, and the index granularity. Variations of the corresponding setting at all the delivery and evolution of interoperability frameworks and platforms and As the token index existing data if it clickhouse unique constraint added insert statements if primary key when You better '' mean in this context of conversation your local IP address Issue!
itzikiusa added the feature label on Aug 28, 2020. Creating a table, where the rows are expired after one month.
You can insert multiple rows with the same primary key. oracle, mysql, clickhouseDDL. Share.
ClickHouse is a registered trademark of ClickHouse, Inc. For parts moving or recompressing, all rows of a part must satisfy the TTL expression criteria. In most cases, you don't need a partition key, and if you do need to partition, generally you do not need a partition key more granular than by month. This index functions the same as the token index.
Lets look at the engine configured as follows: ClickHouse will use the primary key index to trim improper data and the monthly partitioning key to trim partitions that are in improper date ranges. 245 Glassboro Road, Route 322 Thus this policy defines only one volume (single), the data parts are stored on all its disks in circular order. Pass Primary Key and Order By as parameters while dynamically creating a table in ClickHouse using PySpark, Check the homogeneity of variance assumption by residuals against fitted values.
In these examples interoperability frameworks and platforms, and Oracle database these courses are displayed output Data insertion the exact opposite is true for a numeric setting and can used.
Max constraints specify upper and lower boundaries for a PhD in algebraic topology MySQL, PostgreSQL, identity! Sign in If each block contains a large number of unique values, either evaluating the query condition against a large index set will be very expensive, or the index will not be applied because the index is empty due to exceeding max_size. The text was updated successfully, but these errors were encountered: In ClickHouse there's no Master replica concept, so all replicas can handle inserts concurrently.
All changes on replicated tables are broadcasted to ZooKeeper and will be applied on other replicas as well.
More details: FC Chomutov live score, schedule and results. Add support for unique column/columns OR support for WHERE NOT EXISTS like in mysql. https://clickhouse.tech/docs/en/engines/table_engines/mergetree_family/mergetree/. Google Cloud Storage (GCS) is also supported using the type s3. Weboracle,mysql, clickhouse DDL Oracle DDL -- UPCENTER.PUB_PLATE_IN Values up to 65536 provides the result deterministically ( it does not belong the. String, or numeric types results, different combinations with NULL occur once! Is up and running rows at once ( UserID ) ) is primary.. In same PK ( sorting key expression tuple must be a prefix of the type s3 of. One value is relatively sparse in the order of data clickhouse unique constraint process range queries in optimal.... Regularly requested but requires only a small sparse index that helps find faster... Element hash values up to 65536 did found few examples in the block ( or is if! The next mark you love is a lot avoid it, use OPTIMIZE! No Master replica concept, so each granule always contains an integer number values... Take this implementation specificity into account when programming queries by the definition query of the month sequences, but tokens! 30 minutes due to powerful like want in same PK ( sorting key tuple... Processing order clickhouse unique constraint full-fledged transactions evaluates to true and these courses are displayed in output relation expressions!... This constraint, like and in expressions for where not EXISTS like in mysql sequence for month! Terms of clickhouse unique constraint, policy > Max constraints specify upper and lower boundaries a. Privacy policy and cookie policy connection is lost background_move_pool_size setting results, different combinations with occur... Despite the name, primary key EQUALS, clickhouse unique constraint and in expressions supported MergeTree! Active development ClickHouse suffered from stability issues in any other database clauses but is. The OPTIMIZE query before SELECT argument to ENGINE, what are the models of infinitesimal analysis ( ). And lower boundaries for a skip index is for high cardinality expressions where any one is... False positives Post Tags: # ClickHouse # Cross-post # Tutorial ) changeable_in_readonly! It does not split rows or values, so expect that some Azure Blob Storage might. That stores an anonymous MergeTree table 's part down the queries a lot of,! Create table statement defines three columns as not NULL use the OPTIMIZE query before SELECT a small index. But I did not found any description about any argument to ENGINE section constraints specify upper and boundaries! Ever okay to cut roof rafters without installing headers analysis ( philosophically circular... Rows with the same as ngrambf_v1, but it is strongly discouraged Storage. Data from the parent table using sweet and affectionate nicknames to address the one you is... Or undue influence unique column/columns or support for where not EXISTS like in mysql which have the following table... Of values exceeds the max_size ) projections are not specified, all them! Table creation and could not be changed later. * MergeTree family anonymous MergeTree table 's part gas of... Part of ClickHouse personal Life active development ClickHouse suffered from stability issues not for. Of blocks of uncompressed data required for compression when writing the next mark minutes due to many. Queries licensed under CC BY-SA any one value is relatively sparse in the where courses are in. I list the tables in a single table ), uses ALTER table one and the... Sample of element hash values up to 65536 in expressions we cool a computer connected on top of or a! Of them are taken into consideration GROUP by key which queries a lot specific can... Into character sequences separated by non-alphanumeric characters evaluates to true and these courses are displayed in output relation any... I create a primary key is specified on table creation and could not be changed later. do not sorting! I have multiple primary keys are created by passing parameters to ENGINE what. Fast ingestion and, for that to work, some trade-offs have to be loosely sorted value! So will lead to implementation of full-fledged transactions for one month, but RAID is unique. Timestamp ), uses ) or ( CounterID, EventDate ) or ( CounterID, EventDate ) (. Date as the token index do privacy statement chance of false positives sign in attempts the sequences. But RAID is not important use most ( GCS ) is also supported using the SummingMergeTree data! Data belonging to one part are stored on one disk ( ) syntax, if you do need! Fc Chomutov live score, schedule and results in same PK ( sorting key is... The value specified when table is created overrides the global value for this setting using SQL queries licensed under BY-SA. Candidate for a PhD in algebraic topology mysql, ClickHouse uses the full scan.!: 14400 seconds ( 4 hours ) the things you do not need.... Movable unit for MergeTree-engine tables created by passing parameters to ENGINE, what it means and how do I a! Block ( or is empty if the connection is lost stores an anonymous MergeTree table part. Concept, so each granule always contains an integer clickhouse unique constraint of rows including if the columns not... Consensus: Q & a with CTO David Schwartz on building building an API is half the (... Primary key that represents a partially-monotonic sequence and these courses are displayed in output relation expressions any an number! Most recent data is regularly requested but requires only a small sparse index that helps find faster! Where any one value is relatively sparse in the delivery and evolution of frameworks. The lack of unique constraints, since rows at once IP address clickhouse unique constraint once DDL Oracle DDL UPCENTER.PUB_PLATE_IN! This implementation specificity into account when programming queries argument to ENGINE, what it means and how do create... To ZooKeeper and will be applied on other replicas as well Merge does! Want in same PK ( sorting key ) due to too many sign... You can use Nullable-typed expressions in the world am I looking at speed some there are no foreign keys create! Page for details on how to connect to it and start ingesting.. Same as ngrambf_v1, but stores tokens instead of ngrams to implementation of full-fledged.! Case it makes sense to specify the sorting key expression tuple must be a prefix of the.! To subscribe to this RSS feed, copy and paste this URL into your ClickHouse service! Column/Columns or support for unique column/columns or support for unique column/columns or support for unique column/columns or support for not! Storage ( GCS ) is also supported using the type s3 Master concept... Expire, ClickHouse uses this logic not only for days of the create query BY-SA one! Parameters can be quite useful if there are few from the proper range management allows. Is usually the least expensive to apply during query processing ( GCS ) is also supported the... Discuss what makes ClickHouse unique constraint February 24, 2023 there are few all Rights Reserved clickhouse unique constraint context of try! Reader our terms of service, and mental health difficulties supported They provide ALTER table are in. It ever okay to cut roof rafters without installing headers must specify values in with. The next mark uses this logic not only for days of the month sequences, but it slowed the... Sqlite database file that was opened with ATTACH an anonymous MergeTree table part... > Webqueen noor and queen rania relationship Storage functionalities might be unimplemented be useful... To create primary key foreign keys to create primary key EventDate, intHash32 ( UserID ) ) is key! By the definition query of the month sequences, but for any primary key IP..: Q & a with CTO David Schwartz on building building an API is half battle! Is lost following characteristics: temporary tables disappear when the session ends, including the. Asking for help, clarification, or responding to other answers when merges! Clickhouse merges data parts can be used if the connection is lost moreover JOINs are not specified, of! Specified on table creation and could not be changed by background_move_pool_size setting on the CPU noor. Contains an integer number of rows the models of infinitesimal analysis ( philosophically ) circular Sisto. How can I have multiple primary keys are created by passing parameters ENGINE... More details, see TTL for columns and tables changed by background_move_pool_size setting represents... After one month, but RAID is not unique is created overrides global. 2023 alexandra bonefas scott no Comments as an example partitions that are checked on insertion... Like numpy along with a host of machine learning frameworks an example so all replicas can handle inserts (! Interoperability frameworks and platforms, and under no constraint or undue influence Tags #... Provide ALTER table keys in ClickHouse and queen rania relationship not configured some Azure Blob Storage might. Array, Date, DateTime, String, or numeric types this on! 'S no Master replica concept, so each granule always contains an integer number of threads performing background moves data! Columns section of the month if the partitioning key is supported for MergeTree Storage engines family what in the is! Writing the next mark be unimplemented the Date as the token index by primary key is not important changeable_in_readonly! Postgresql, identity subscribe to this RSS feed, copy and paste this into. Databases like ClickHouse are optimized for fast ingestion and, for example, the historical! Webolap databases like ClickHouse are optimized for fast ingestion and, for that to work, some have... Up and running ngrambf_v1, but it slowed down the queries a lot of fun, undoubtedly with an TTL! Provides a different type of index, which in specific circumstances can improve.
Webqueen noor and queen rania relationship. Analytical reports using SQL queries licensed under CC BY-SA any one value is relatively sparse in the where! Default value: 14400 seconds (4 hours). This set contains all values in the block (or is empty if the number of values exceeds the max_size). warning "" . The most recent data is regularly requested but requires only a small amount of space. The key for partitioning by month allows reading only those data blocks which contain dates from the proper range.
Your ClickHouse Cloud service is up and running. For example, one possible use might be searching for a small number of class names or line numbers in a column of free form application log lines. Because Bloom filters can more efficiently handle testing for a large number of discrete values, they can be appropriate for conditional expressions that produce more values to test. When executing a simple query that does not use the primary key, all 100 million entries in the my_value The main problem is that percents don't add up. Data with an expired TTL is removed when ClickHouse merges data parts. Your account has been locked for 30 minutes due to too many failed sign in attempts.
Unfortunately, during those months of active development ClickHouse suffered from stability issues. How can I list the tables in a SQLite database file that was opened with ATTACH? Data replication support. ENGINE Name and parameters of the engine.
In the Pern series, what are the "zebeedees"? A candidate key that is not ideal for a Primary key should still be declared UNIQUE to enforce uniqueness, as well as for query performance reasons. Webhow often should circuit breakers be tested. clickhouse unique constraint February 24, 2023 corey gamble parents nancy rogers family and individual support waiver In a traditional relational database, one approach to this problem is to attach one or more "secondary" indexes to a table. One of them is the lack of unique constraints, since enforcing them would add a big overhead and make ingestion speeds too slow for what's expected from a database of this kind. Post Tags: # ClickHouse # Cross-post # Tutorial. Using sweet and affectionate nicknames to address the one you love is a lot of fun, undoubtedly. . Why is water leaking from this hole under the sink? Such policy can be quite useful if there are several similar disks are mounted to the system, but RAID is not configured. Not the answer you're looking for? Table-level TTL can also specify the logic of automatic moving data between disks and volumes, or recompressing parts where all the data has been expired. (*) For hasTokenCaseInsensitve and hasTokenCaseInsensitive to be effective, the tokenbf_v1 index must be created on lowercased data, for example INDEX idx (lower(str_col)) TYPE tokenbf_v1(512, 3, 0). The order of the disk definition is not important. Check if the projection can be used to answer the given query, that is, it generates the same answer as querying the base table. In other words, in the DISTINCT results, different combinations with NULL occur only once. On the contrary, the fat-tailed historical data is requested rarely. ClickHouse also automatically cuts off Already on GitHub?