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If you are interested in reading about JOINS in detail, ClickHouse has good blogs around it: - https://clickhouse.com/blog/clickhouse-fully-supports-joins-part

If you are interested in reading about JOINS in detail, ClickHouse has good blogs around it: - https://clickhouse.com/blog/clickhouse-fully-supports-joins-part1 https://clickhouse.com/blog/clickhouse-fully-supports-joins-... - https://clickhouse.com/blog/clickhouse-fully-supports-joins-hash-joins-part2 https://clickhouse.com/blog/clickhouse-fully-supports-joins-... - https://clickhouse.com/blog/clickhouse-fully-supports-joins-full-sort-partial-merge-part3 https://clickhouse.com/blog/clickhouse-fully-supports-joins-... - https://clickhouse.com/blog/clickhouse-fully-supports-joins-direct-join-part4 https://clickhouse.com/blog/clickhouse-fully-supports-joins-... - https://clickhouse.com/blog/clickhouse-fully-supports-joins-how-to-choose-the-right-algorithm-part5 https://clickhouse.com/blog/clickhouse-fully-supports-joins-...

tucnak 3y ago
I'm sorry but Clickhouse isn't SQL-compliant so it has no business teaching us JOIN.
- 392 3y ago
  No database is fully SQL compliant. Though clickhouse can at times be painfully so. https://stackoverflow.com/questions/784900/why-does-no-database-fully-support-ansi-or-iso-sql-standards https://stackoverflow.com/questions/784900/why-does-no-datab...
  - tucnak 3y ago
    > PostgreSQL supports most of the major features of SQL:2023. Out of 177 mandatory features required for full Core conformance, PostgreSQL conforms to at least 170. In addition, there is a long list of supported optional features. https://www.postgresql.org/docs/current/features.html https://www.postgresql.org/docs/current/features.html Clickhouse is simply a joke in comparison. No basic cursor support, no transactions, incomplete comparison operators, no single-row SELECT with GROUP BY and HAVING clauses grouped views, no procedures, no anti-joins or WHERE EXISTS, for that matter. The list goes on... it's basically impossible to write SQL to any degree of sophistication in Clickhouse.
    - wotwmn 3y ago
      > anti-joins Does exist. > single-row SELECT with GROUP BY and HAVING clauses grouped views If it's about grouping sets they do exist. > no procedures parametrized views/UDF/executable UDF (UDTF) exist. > WHERE EXISTS, Exists, but without Correlated Sub query part, which is honestly a joke because of how subpair performance it usually have compared to other alternatives. Can you remind, does SQL:2023 standard finally allow you to use DISTINCT keyword in WINDOW functions? Or people still forced to do horrible hacks with correlated subqueries or joins to do extremely simple thing like count Distinct in running window of X days? > it's basically impossible to write SQL to any degree of sophistication in Clickhouse. It's says more about engineer not DBMS.

tucnak 3y ago

I'm sorry but Clickhouse isn't SQL-compliant so it has no business teaching us JOIN.

392 3y ago
No database is fully SQL compliant. Though clickhouse can at times be painfully so. https://stackoverflow.com/questions/784900/why-does-no-database-fully-support-ansi-or-iso-sql-standards https://stackoverflow.com/questions/784900/why-does-no-datab...
- tucnak 3y ago
  > PostgreSQL supports most of the major features of SQL:2023. Out of 177 mandatory features required for full Core conformance, PostgreSQL conforms to at least 170. In addition, there is a long list of supported optional features. https://www.postgresql.org/docs/current/features.html https://www.postgresql.org/docs/current/features.html Clickhouse is simply a joke in comparison. No basic cursor support, no transactions, incomplete comparison operators, no single-row SELECT with GROUP BY and HAVING clauses grouped views, no procedures, no anti-joins or WHERE EXISTS, for that matter. The list goes on... it's basically impossible to write SQL to any degree of sophistication in Clickhouse.
  - wotwmn 3y ago
    > anti-joins Does exist. > single-row SELECT with GROUP BY and HAVING clauses grouped views If it's about grouping sets they do exist. > no procedures parametrized views/UDF/executable UDF (UDTF) exist. > WHERE EXISTS, Exists, but without Correlated Sub query part, which is honestly a joke because of how subpair performance it usually have compared to other alternatives. Can you remind, does SQL:2023 standard finally allow you to use DISTINCT keyword in WINDOW functions? Or people still forced to do horrible hacks with correlated subqueries or joins to do extremely simple thing like count Distinct in running window of X days? > it's basically impossible to write SQL to any degree of sophistication in Clickhouse. It's says more about engineer not DBMS.