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- Set Operations 11228
- Set operations allow queries to be combined according to set operation semantics . Set operations refer to the UNION [ALL] , INTERSECT [ALL] and EXCEPT [ALL] clauses. The vanilla variants use set semantics, i.e., they eliminate duplicates,
...ws an error. Vanilla UNION (Set Semantics) The vanilla UNION clause follows set semantics, therefore it performs duplicate elimination, i.e., only unique rows will be included in the result. SELECT * FROM range(2) t1(x) UNION SELECT * FROM range(3) t2(x); x...1 0 UNION ALL (Bag Semantics) UNION ALL returns all rows of both queries following bag semantics, i.e., without duplicate elimination. SELECT * FROM range(2) t1(x) UNION ALL SELECT * FROM range(3) t2(x); x 0 1 0 1 2 UNION [ALL] BY NAME The UNION [ALL] BY N...Berlin Germany NULL NULL Amsterdam NULL 10 2022-10-14 UNION BY NAME follows set semantics (therefore it performs duplicate elimination), whereas UNION ALL BY NAME follows bag semantics. INTERSECT The INTERSECT clause can be used to select all rows that occu... - https://man.mtool.work/duckdb/2.0/sql/query_syntax/setops.html
- Metrics 7485
- DuckDB provides a set of metrics that can be used to monitor the performance and health of the database. Metrics are named ⟨group⟩.⟨metric⟩ , e.g., query.total_time or operator.timing . The set of collected metrics is controlled with the tr
...n_rewriter , optimizer.late_materialization , optimizer.cte_inlining , optimizer.row_group_pruner , optimizer.top_n_window_elimination , optimizer.common_subplan , optimizer.join_elimination , optimizer.window_self_join , optimizer.projection_pullup , optim... - https://man.mtool.work/duckdb/2.0/dev/metrics.html
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