Results of 1 - 6 of about 6 for aggregations (0.001 sec.)
- Pivot Internals 12174
- PIVOT Pivoting is implemented as a combination of SQL query re-writing and a dedicated PhysicalPivot operator for higher performance. Each PIVOT is implemented as set of aggregations into lists and then the dedicated PhysicalPivot operator
...statement's IN clauses. After the IN clauses have been populated with ENUM s, the query is re-written again into a set of aggregations into lists. For example: PIVOT cities ON year USING sum(population); is initially translated into: CREATE TEMPORARY TYPE _...0 2010 2020 NL Amsterdam 1005 1065 1158 US Seattle 564 608 738 US New York City 8015 8175 8772 The rewrite into list-based aggregations shown above is used only when the number of distinct pivot values exceeds the pivot_filter_threshold configuration option... - https://man.mtool.work/duckdb/2.0/internals/pivot.html
- GROUP BY Clause 10693
- The GROUP BY clause specifies which grouping columns should be used to perform any aggregations in the SELECT clause. If the GROUP BY clause is specified, the query is always an aggregate query, even if no aggregations are present in the SE
... - https://man.mtool.work/duckdb/2.0/sql/query_syntax/groupby.html
- SELECT Statement 9450
- The SELECT statement retrieves rows from the database. Examples Select all columns from the table tbl : SELECT * FROM tbl; Select the rows from tbl : SELECT j FROM tbl WHERE i = 3; Perform an aggregate grouped by the column i : SELECT i, su
...ROM clause. GROUP BY and HAVING Clauses The GROUP BY clause specifies which grouping columns should be used to perform any aggregations in the SELECT clause. If the GROUP BY clause is specified, the query is always an aggregate query, even if no aggregations... - https://man.mtool.work/duckdb/2.0/sql/statements/select.html
- Parquet Tips 7732
- Below is a collection of tips to help when dealing with Parquet files. Tips for Reading Parquet Files Use union_by_name When Loading Files with Different Schemas The union_by_name option can be used to unify the schema of files that have di
...thread count would improve the speed of highly selective queries, but slow down queries that must scan the whole file like aggregations. To write a query to a Parquet file with a different row group size, run: COPY (FROM generate_series(100_000)) TO 'row-gro... - https://man.mtool.work/duckdb/2.0/data/parquet/tips.html
- Indexing 7494
- DuckDB has two types of indexes: zonemaps and ART indexes. Zonemaps DuckDB automatically creates zonemaps (also known as min-max indexes) for the columns of all general-purpose data types . Operations like predicate pushdown into scan opera
...tors and computing aggregations use zonemaps. If a filter criterion (like WHERE column1 = 123 ) is in use, DuckDB can skip any row group whose min-max ran... - https://man.mtool.work/duckdb/2.0/guides/performance/indexing.html
- I/O 7238
- Warning DuckDB ships with safe defaults. The configuration options described on this page are advanced options, so proceed with caution when changing them. Asynchronous I/O New Asynchronous I/O was introduced in DuckDB 2.0. Starting with v2
...pools: The regular pool contains the worker threads, which perform the actual query processing (e.g., decoding, joins and aggregations). Its size is controlled by the threads setting and defaults to the number of CPU cores. Regular threads prioritize query... - https://man.mtool.work/duckdb/2.0/data/io.html
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