Mar 27, 2020 · Here there are multiple BEST_BID and BEST_ASK for a single timestamp. ClickHouse has 6 different algorithms for the join execution, or allow the query planner to adaptively choose and dynamically change the algorithm at runtime, depending on resource availability and usage. 01 is many times slower compared to 22. Normal functions do not change a set of rows, but just change the values in each row (map). 类似于 Feb 1, 2019 · Clickhouse-driver uses a similar format in both directions. However the query can not be executed, if join keys from the left and the right tables cannot be converted to a single type (for example, there is no data type that can hold all values from both UInt64 and Int64 , or String and Int32 ). 99. It seems to me that he should execute the first subquery and get a table weighing ~1 GB, then join it with the second table and as a result get a table weighing ~1. Using the example you've provided: WITH events_block AS (. The syntax should look familiar, and you can view the docs page on JOIN for all the details: Nov 22, 2019 · Sorry for the poorly written issue report. One of the most common operations in SQL is the join, which combines data from two or more tables. We'll use the query from the first example, it's the simplest one and focuses just on the "as of" aspect: SELECT s. Jun 27, 2024 · - Finding clickhouse/clickhouse versions matching "0. Provide a name for a query When adding numbers, ClickHouse automatically sets the single_value type for the data type of the array. Successfully merging a pull request may close this issue. Documentation provides more in-depth information. Hot Network Questions Mar 3, 2023 · There is a huge performance degradation of ASOF join between versions 22. count row only if specified expression is true. FROM table1. In 22. b != t2. Overview of ClickHouse Architecture. 1. 语法: (ON <expr_list>)|(USING <column_list>) 从表达式 ON 从子句和列 Mar 2, 2023 · The ASOF JOIN, implemented for ClickHouse in 2019 by Martijn Bakker and Artem Zuikov, provides non-exact matching capabilities. The function adds a NULL element to an array, and the type of array elements converts to Nullable. DB::Exception: ASOF join not supported for typeUInt16 When I changed my field for asof_con Aug 21, 2022 · clickhouse. entity_id AND states. The Cell Towers dataset imports a CSV into ClickHouse. Understanding the intricacies of ClickHouse’s advanced join types is essential for optimizing queries and unlocking the full potential of your data. Jun 24, 2019 · I think you need ASOF JOIN. 0. 2 variants. Let's have a quick overview of the syntax needed to get the ASOF JOIN in a few of the popular databases. event_id) ctrl + c. 01 it runs times slower, less than 5M/sec, actually the longer query runs the slower it becomes. SELECT * FROM some_table SETTINGS optimize_read_in_order=1, cast_keep_nullable=1; Edit this page. numbers ANY LEFT JOIN ( SELECT number * 2 AS number, (number * 10) + 1 AS joined FROM system. It is called “vectorized query execution” and it helps lower the cost of The INTERSECT clause returns only those rows that result from both the first and the second queries. Tutorial shows how to set up and query a small ClickHouse cluster. id = t2. sumIf. Grace hash join. 它是支持SQL的数据库中的常见操作,它对应于 关系代数 加入。. Here are some examples: #10913. Clickhouse: Mapping BETWEEN filtering from an array. Complex JOIN in ClickHouse (using subquery and left join) Here’s an example of a more complex join in ClickHouse, using a subquery and a left join: -- create two sample tables. password: "SUPER_SECRET" with your password. Examples. This function takes an array as an argument, and propagates the Aug 25, 2020 · Update: Apparently you cannot use columns from out query in correlated subquery in Clickhouse. If a row from the left table doesn’t have an exact match in the right table, then the closest matching row from the right table is used as a match instead. Let's size the temp_calls tables - 20 GB. SELECT sumIf ( age, date < '2022-01-01') FROM tbl ctrl + c. I cannot use subqueries because I have to correlate the data and clickhouse does not support correlated queries. All the values in columns are simply copied, except the values in the column Limits sizes of right-hand join data blocks in partial merge join algorithm for JOIN queries. Join通过使用一个或多个表的公共值合并来自一个或多个表的列来生成新表。. Validating and checking keys We can simply check if JSON is valid using isValidJSON function: 1. timestamp_, 10) and addSeconds (t2. How to reproduce Which ClickHouse server version to use 22. s3. Example: CREATE TABLE test. This optimization additionally resolves several related, preexisting issues in ClickHouse. The output of the EXPLAIN command will show the execution plan for the query, including the join order. CREATE TABLE orders (. date > '2022-01-01'. Jun 26, 2022 · Find closest combination of key, timestamp, value for list of key, timestamp combinations. If the regexp is empty, it will split the string s into an array of single characters. There are 2 main problems. We would love to hear feedback about your experience Jun 23, 2024 · ASOF JOIN support across popular databases. Multiple INTERSECT statements are executed left to right if parentheses are not specified. 12 and 23. I want to choose the closest trailing BEST_ASK for each BEST_BID. event phase. Jan 20, 2020 · You signed in with another tab or window. You can also define the compression method for each individual column in the CREATE TABLE query. start and t1. FROM event. bucket: "my-clickhouse-backups" with your S3 bucket name. 168. tbl1 t1. timestamp_ be Oct 13, 2022 · It enables ClickHouse to “see” and select data from remote transaction tables in MySQL. ClickHouse server: Splits right-hand join data into blocks with up to the specified number of rows. JOIN table2 ON table1. numbers LIMIT 10 ) AS js2 USING (number) LIMIT 10 Invalid expression / Unexpected token. For MergeTree-engine family you can change the default compression method in the compression section of a server configuration. date < '2022-01-01'. Is the FOCAL syntax for Alphanumeric Numbers ("0XYZ") documented anywhere? Apr 28, 2023 · INNER and LEFT join types and all strictness settings except ASOF are supported. Each insert sent to ClickHouse causes In other words, the data set in the IN clause will be collected on each server independently, only across the data that is stored locally on each of the servers. The INSERT params also support dictionary organization as well as generators, as we’ll see in a later section. Learn more about the shortcuts Select countIf usage example. timestamp_, 10) I am trying to join them but clickhouse only supports one inequality condition. 01. Extremely deep SIMD optimization with AVX-2 and SSE4. * ASOF JOIN — join nearest value by inexact match (<, >, ≤, ≥) — for time series correlation. Example Mar 17, 2014 · For ASOF JOIN*. ClickHouse, an open-source columnar database management system, has gained popularity for its exceptional query performance, especially when it comes to handling complex joins efficiently. timestamp ORDER BY This is the basic case of what ARRAY JOIN clause does. 它可以被视为执行 JOIN 并具有数组或嵌套数据结构。. If you'd like to know more about provider signing, you can read about it here: Feb 23, 2021 · Currently, the asof join allow to have one closest match condition, like>, >=, <, <=. So I completely ran out of options and start thinking that It is not even possible to do this. This blog post described and compared in detail the 3 ClickHouse join algorithms that are based on in Jan 1, 2022 · Select sumIf query example. arrayJoin function. Permutation via Recursion: The recursion method involves recursively selecting each element in the set and computing the permutations of the remaining elements. data_feed AND a. The following assumptions are made: The field name (function argument) must be a constant. All these JSON functions are based on strong assumptions about what the JSON can be. Feel free to check all configuration options here. limits by needed memory for a query. start=t2. Reload to refresh your session. The smaller dataset is used to create an in-memory hash table, which is then used to look up rows from the larger table. Joins are fully supported in ClickHouse with support for all standard SQL JOIN types. end=t2. When reading, the indexes of tables that are actually being read are used, if they exist. SELECT id. time >= orders. In ClickHouse, Hash Joins are a powerful method for combining data from multiple tables efficiently. ts ts, s. It works by automatically moving part of WHERE condition to prewhere stage. countIf. 4 days ago · note::: Since the AD security groups were prefixed in the example - i. timestamp > prev_states. spending+10) and (t1. 7. Specify the path to our XML file Mar 29, 2022 · t1. Data Skipping Indices. sudo nano config. Joining Tables in ClickHouse. If you have any questions about ClickHouse or ClickHouse Cloud, please join our community Slack channel or engage with our open source community on GitHub. ClickHouse recommend using built-in table functions in ClickHouse which provide a better alternative for ad-hoc querying scenarios (Postgres, MySQL, MongoDB, etc). time ORDER BY time ASC Received exception from server (version 21. SELECT * FROM tbl1 t1 JOIN tbl2 t2 ON (t1. entity_id = prev_states. These changes improved JOIN speed on INNER and LEFT JOINs by over 180x. second table to join to tbl1. Feb 27, 2017 · Indeed, joining many tables is currently not very convenient but there are plans to improve the join syntax. clickhouse_ad_db1_users- when the system retrieves them, the prefix will be removed and the system will look for a ClickHouse role called ad_db1_users to map to clickhouse_ad_db1_users. 2 - Installed clickhouse/clickhouse v0. Migrating tables to ClickHouse generally proceeds as follows. Other ways to make settings see here. Aug 5, 2019 · It would be useful, for example, if we want to join previous entity state to current state. ClickHouse supports both the WITH <expression> AS <identifier> as well as the WITH <identifier> AS <subquery expression> syntaxes. EXPLAIN AST Dump query AST. WHERE id%2=0 AND id IN. end and (t1. timestamp AND a. Splits a string into substrings separated by a regular expression. This causes ClickHouse to handle the batching on the server-side. should be one of the data types: UInt32, UInt64, Float32, Float64, Date, and DateTime Code: 169. Hash Join: The default and most commonly used. I'm using rowNumberInBlock() in an ASOF join but I am getting results that depend on the range of timestamps I ask for. timestamp_ between subtractSeconds (t2. If a row from the left table doesn ClickHouse Cloud ClickHouse as a service, built by the creators and maintainers. Jan 3, 2022 · Clickhouse ASOF left Join right table Nullable column is not implemented. Jul 10, 2022 · How to use array join to extract and query varying attributes using map keys and values; How to set up ClickHouse on Docker with ODBC to connect to a Microsoft SQL Server (MSSQL) database; Simple example flow for extracting JSON data using a landing table with a Materialized View; Mapping Windows Active Directory security groups to ClickHouse roles Here is an example of using the EXPLAIN command to determine the join order in ClickHouse: EXPLAIN SELECT *. Also note that if many joins are necessary because your schema is some variant of the star schema and you need to join dimension tables to the fact table, then in ClickHouse you should use the external dictionaries feature instead. b AND table_2. Usually by date/time. b is to use UNION ALL for > and <. There's plenty more settings you can configure, and remote storages other than S3. Does Justice Sotomayor's "Seal Team 6" example, in and of itself, explicitly give the Jun 7, 2023 · In our second post, we described and compared in detail the three ClickHouse join algorithms from the chart above that are based on in-memory hash tables: Hash join; Parallel hash join; Grace hash join; As a reminder: Hash join and parallel hash join are fast but memory-bound. Can be NULL. 这是 ARRAY JOIN 语句最基本的场景。. github. It is enabled by default even if PREWHERE clause is not specified explicitly. If possible (ie one key value spans multiple granules of single range), pick granules which has the closest timestamp value. SELECT queries perform data retrieval. Parallel hash join. Jan 18, 2024 · Typically, a feature store will consist of up to 4 main components: Data source - While this can be as simple as a CSV file, it is often a database or data lake with files in a format like Iceberg and accessible through a query engine. Choose Join Types: ClickHouse supports various join types, including inner, left, and outer joins. If I ask for a narrow range of timestamps I get the results I expect, but when I try to The syntax should look familiar, and you can view the docs page on JOIN for all the details: ClickHouse also provides additional non-standard SQL JOIN types useful for analytical workloads and for time-series analysis, including the ASOF join. table to select data from. Hash Join: The default and most commonly used Apr 27, 2021 · Clickhouse ASOF left Join right table Nullable column is not implemented. 2 (self-signed, key ID D7089EE5C6A92ED1) Partner and community providers are signed by their developers. For example, SELECT count() FROM table_1 ASOF LEFT JOIN table_2 ON table_1. Asof join in 23. DB::Exception: Received from 192. accel accel, e. Jul 8, 2022 · Syntax. The workaround for the condition t1. May 12, 2023 · ANY SELECT number, joined FROM system. CREATE TABLE states ( entity_id UUID state INT8 timestamp DateTime ) SELECT state AS cur_state, prev_state FROM states ASOF JOIN states AS prev_states ON states. The INTERSECT operator has a higher Prewhere is an optimization to apply filtering more efficiently. 一个表连接的特殊情况通常被称为 “self-join”. Algorithm Selection: ClickHouse primarily uses two algorithms for JOIN operations: Hash Join and Merge Join. e. The intent is similar to the arrayJoin function, but the clause functionality is broader. JOIN子句. Union by element of two array of array in clickhouse. name of the column to sum. Mar 17, 2023 · The ASOF JOIN, implemented for ClickHouse in 2019 by Martijn Bakker and Artem Zuikov, provides non-exact matching capabilities. This will work correctly and optimally if you are prepared for this case and have spread data across the cluster servers such that the data for a single UserID resides entirely on a single server. For hasAll function for arrays. ClickHouse primarily uses two algorithms for JOIN operations: Hash Join and Merge Join. SELECT * FROM events LIMIT 3. will select rows matching tbl1 and tbl2. . Initiate a CTE using WITH. key. This is a very unusual function. 12. Apr 20, 2023 · This chart gives an overview of these algorithms based on their relative memory consumption and execution time: This blog post will describe and compare in detail the three ClickHouse join algorithms from the chart above that are based on in-memory hash tables: Hash join. Here is an example output: Oct 26, 2022 · Clickhouse provides several functions to work with JSON data, including validating JSON data itself. 0. Slack and Telegram allow chatting with ClickHouse users in real-time. Transformation engine (optional) - Raw data needs to be transformed into features. (. Includes examples and code snippets. 2. age. It’s time to set up Clickhouse. We need the tag, it’s the path to a file that describes the dictionaries structure. These examples should, however, be reproducible on an equivalently sized self-managed cluster. As the types comes from the table definition (and your order_table must have a definition of order_timestamp like Nullable(Int64)), ClickHouse will refuse to run with the exception like ClickHouse exception, code: 48,DB::Exception: ASOF join over right table Nullable Apr 7, 2022 · I have this query I am trying to join 2 table based on 4 conditions select * from table1 t1 asof left join table2 t2 on t1. Meanwhile, MySQL handles transactional changes efficiently and safely. The result of INTERSECT can contain duplicate rows. Collect a summary of column/expression values for every N granules. 5): Code: 403. Clickhouse will work as you expected: it will execute your request on each shard locally and then combine results at initiator. The sample datasets include: The UK Property Price Paid dataset is a good starting point with some interesting SQL queries. Nov 22, 2023 · A Python client working example for connecting to ClickHouse Cloud Service; Terraform example on how to use Cloud API; How to use array join to extract and query varying attributes using map keys and values; How to set up ClickHouse on Docker with ODBC to connect to a Microsoft SQL Server (MSSQL) database; Simple example flow for extracting Apr 30, 2024 · Here are the complete results of ClickHouse performance tests, with the highlights shown below. order_id Int32, customer_id Int32, order_date Date, total_price Float32. They try to do as little as possible to get the job done as quickly as possible. SYNTAX — Query text after AST-level optimizations. Developer: youennL-cs (ContentSquare) and Maksim Kita. data_feed = b. spending-10 and t2. Allows ClickHouse to connect to external databases via JDBC. Example. The calls table size is 100 GB, but the daily data size is no more than 1 GB. I have tried another query using with clause and has but has May 5, 2021 · Here is an example to work with:-- Actual table to store the data fetched from an Apache Kafka topic CREATE TABLE data( a DateTime, b Int64, c Sting ) Engine=MergeTree ORDER BY (a,b); -- Materialized View to insert any consumed data by Kafka Engine to 'data' table CREATE MATERIALIZED VIEW data_mv TO data AS SELECT a, b, c FROM data_kafka; -- Kafka Engine which consumes the data from 'data select * from A as a LEFT ASOF JOIN B as b on a. Bonus: New Documentation Use it at your own risk. 2" - Installing clickhouse/clickhouse v0. FROM <left_subquery>. If no match is found for this regular expression, the string s won't be split. Nov 2, 2016 · 5. Select the service that you will connect to and click Connect: Choose Native, and the details are available in an example clickhouse-client command. timetamp <= b. Unloads prepared blocks to disk if it is possible. xml file using nano text editor: cd /etc/clickhouse-server. INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN queries support the implicit type conversion for "join keys". Permutation via Recursion: 2. Permutation via Cross Join: Conclusion. Let us worry about the infrastructure, and get querying! Если в запросе отсутствуют секции distinct, group by, order by, подзапросы в in и join, то запрос будет обработан полностью потоково, с использованием o(1) количества оперативки. sum specified column value if expression is true. Nested-Loop Join is suitable when one of the tables is relatively small and fits into memory. first table with alias. It’s efficient for unequal dataset sizes (one small, one large). 100:9091. Learn how to perform a left join with null values in ClickHouse with this detailed guide. The queries must match the number of columns, order, and type. The left join is a type of join that retains all rows from the left table The details for your ClickHouse Cloud service are available in the ClickHouse Cloud console. ClickHouse has 6 different algorithms for the join execution, or allow the query planner to adaptively May 20, 2020 · Setting up Clickhouse. What works for me is sharding calculation query by id%N using subqueries and union all results then. 对于包含数组列的表来说是一种常见的操作,用于生成一个新表,该表具有包含该初始列中的每个单独数组元素的列,而其他列的值将被重复显示。. From here you can Open SQL console: If you are using self-managed ClickHouse you can connect to the SQL console at https:// hostname :8443/play (check with your ClickHouse administrator for the details). In 23. Further reading. The limit is 10 GB. Aggregate functions compress a set of rows (fold or reduce). Let’s edit the config. Its name comes from the fact that it can be looked at as executing JOIN with an array or nested data structure. JOIN. Join tables in ClickHouse without equal expressions. May 31, 2023 · For our examples, we utilize a ClickHouse Cloud cluster with a total of 60 cores and 240GB of RAM per node. Otherwise, full tables will be pushed to memory to perform the join causing the issues you're experiencing. They fall under the category of “merge joins,” where ClickHouse takes advantage of sorted data structures to speed up the joining process. Jun 16, 2020 · Go to the config file: cd /etc/clickhouse-server. We already showed an example of a SELECT statement using functions to generate output. QUERY TREE — Query tree after Query Tree level optimizations. Simplified example to reproduce the problem: 1st table contains Urls Jan 6, 2024 · Internal Working of JOINs in ClickHouse. ClickHouse doesn't have a proper optimizer, so the right tables of the join require to be filtered before performing a join. key = table3. a == table_2. t <= table_1. Oct 7, 2023 · This request runs out of memory. YouTube channel has a lot of content about ClickHouse in video format. region: "eu-central-1" with the correct AWS region for your bucket. key = table2. The role of PREWHERE clause is only to control this optimization if you think that you know how to do it better than it happens by default. The base case occurs when there is only one element remaining, at which point the permutation is complete. Writing to a table is not supported. JOIN query example. IE during index scan ClickHouse will do: Identify ranges/granules where needed exact key values could be. Algorithm Selection. ASOF JOIN is useful when you need to join records that have no exact match. A nested data structure is like a table inside a cell. Reading is automatically parallelized. Possible values: Any positive integer. From your ClickHouse Cloud services list, choose the service that you will work with and click Connect. To implement the JDBC connection, ClickHouse uses the separate program clickhouse-jdbc-bridge splitByRegexp. spending between t2. Supports all types of queries, not only SELECT. Your ClickHouse queries can join local tables on transaction data whose natural home is MySQL. Example: — to correlate stock prices with weather sensors. The arrayJoin function takes each row and generates a set of rows (unfold). col1 — column to join on, ORDER BY col1 — sort values, LIMIT 1000000, 1 — offset by the number of rows we want to process in a single iteration (this should be executed for each iteration with respective offset). transform(T, Array(T), Array(U), U) -> U. Hash Joins are particularly beneficial when dealing with large datasets and complex join conditions. It uses a regular expression string regexp as the separator. ClickHouse is a true column-oriented DBMS. PLAN — Query execution plan. Nested-Loop Join. ClickHouse supports two main types of joins: Nested-Loop Join and Merge-Scan Join. SELECT 1. See the docs for more insert examples. T and U can be numeric, string, or Date or DateTime types. Indexes each block with its minimum and maximum values. For example, the first argument could have type Int64, while the second argument could have type Array(UInt16). ClickHouse also provides additional non-standard SQL JOIN types useful for analytical workloads and for time-series analysis, including the ASOF join. Alternatively, start your ClickHouse Cloud cluster today, and receive $300 of credit. You signed out in another tab or window. Examples: Jun 30, 2023 · Saved searches Use saved searches to filter your results more quickly Mar 16, 2023 · If you are curious to try ClickHouse Cloud, we offer $300 of credits during a 30-day trial to help you get started with your use case. Mar 22, 2021 · I'm trying to split 2 arrays using arrayJoin() my table: create table test_array( col1 Array(INT), col2 Array(INT), col3 String ) engine = TinyLog; Apr 3, 2019 · how to use array join in Clickhouse. Syntax: SELECT <expr_list>. For more information about the types of data in ClickHouse, see “Data types”. ) ENGINE = MergeTree ORDER BY order_id; AST — Abstract syntax tree. The NYPD Complaint Data demonstrates how to use data inference to simplify Optimize for Filtering: Apply filters as early as possible in the join sequence. SELECT time, price, qty FROM orders ASOF INNER JOIN trades ON trades. If a row from the left table doesn’t have an exact match in the Aug 24, 2021 · Let's first try to ASOF JOIN on the time column alone. Mar 24, 2022 · Saved searches Use saved searches to filter your results more quickly Use asynchronous inserts as an alternative to both batching data on the client-side and keeping the insert rate at around one insert query per second by enabling the async_insert setting. The setting value is applied only to this query and is reset to default or previous value after the query is executed. The Merge engine (not to be confused with MergeTree) does not store data itself, but allows reading from any number of other tables simultaneously. SELECT countIf (date > '2022-01-01') FROM tbl ctrl + c. Let’s delve into each join type, explain how they work, and provide practice data set examples. Иначе запрос может съесть ClickHouse has special functions for working with simplified JSON. That means that you can use join of the Distributed table with local tables to achieve expected result: SELECT xxx. tbl2 t2. The joined data from the right-hand side table needs to fit into memory. 4+ Which interface to use, if matters Non-default settings, if any CREATE TABLE statements for all tables Nov 19, 2021 · I can assume that you are joining 3 Distributed tables: t1d, t2d, t3d. JOIN table3 ON table2. The parameters of a nested data structure – the column names and types – are specified the same way as in a CREATE TABLE query. 1 GB. Each table row can correspond to any number of rows in a nested data structure. ClickHouse is a fast, in-memory columnar database that is well-suited for analytical workloads. visits. timestamp - interval '1 minute' would be very useful for my use case but it doesn't seem to be possible with just ASOF join Jan 4, 2022 · Current implementation of ASOF LEFT JOIN requires that the right side column used in inequality to be a non-nullable type. Whenever possible, operations are dispatched on arrays, rather than on individual values. Data is stored by columns, and during the execution of arrays (vectors or chunks of columns). PIPELINE — Query execution pipeline. By default, ClickHouse is writing data synchronously. Aug 25, 2023 · We can check that for the example query via EXPLAIN SYNTAX (that returns the syntactically optimized version into which a query gets rewritten before being executed) (View Highlight) The ASOF JOIN, implemented for ClickHouse in 2019 by Martijn Bakker and Artem Zuikov, provides non-exact matching capabilities. Syntax. Developers: Raul Marin and Maksim Kita. Jan 14, 2021 · Clickhouse ASOF left Join right table Nullable column is not implemented. Use this summaries to skip data while reading. xml. t. This function takes an array as an argument, and propagates the source row to multiple rows for the number of elements in the array. . expression to check (should we add this row value to the total sum) ASOF JOIN (by Citadel Securities) Join data by inexact (nearest) match. The New York Taxi Data has an example of how to insert data from S3 into ClickHouse. JOIN in ClickHouse; Query execution resources limits in ClickHouse; ClickHouse primary keys and query performance Jan 26, 2023 · 7. ::: Create example databases. By default, ClickHouse applies lz4 compression in the self-managed version, and zstd in ClickHouse Cloud. DB::Exception: Received from localhost:9000. Indices are available for MergeTree family of table ARRAY JOIN子句. Feb 15, 2023 · Describe the situation ASOF LEFT JOINs query uses more memory and time. If you are using self-managed ClickHouse, the connection details are set by your ClickHouse administrator. Select the appropriate join type for each relationship to retain necessary data. For example, filter by date or customer type before joining large datasets. I experience same problems with joining 2 huge distributed tables. You switched accounts on another tab or window. expression to check ( date column has date less than 10 days ago) tbl. The same letter (T or U) means that types must be mutually compatible and not necessarily equal. 12 following query runs with steady performance of ~30M rows/sec. timetamp >= b. ilghxgkdhhejfnuelbei