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- HAVING Clause 13357
- The HAVING clause can be used after the GROUP BY clause to provide filter criteria after the grouping has been completed. In terms of syntax the HAVING clause is identical to the WHERE clause, but while the WHERE clause occurs before the gr
...ccurs after the grouping. Examples Count the number of entries in the addresses table that belong to each different city , filtering out cities with a count below 50: SELECT city, count(*) FROM addresses GROUP BY city HAVING count(*) >= 50; Compute the av...erage income per city per street_name , filtering out cities with an average income bigger than twice the median income : SELECT city, street_name, avg(income) FROM address... - https://man.mtool.work/duckdb/2.0/sql/query_syntax/having.html
- QUALIFY Clause 13119
- The QUALIFY clause is used to filter the results of WINDOW functions . This filtering of results is similar to how a HAVING clause filters the results of aggregate functions applied based on the GROUP BY clause . The QUALIFY clause avoids t
...he need for a subquery or WITH clause to perform this filtering (much like HAVING avoids a subquery). An example using a WITH clause instead of QUALIFY is included below the QUALIFY exam...ples. Note that this is filtering based on WINDOW functions , not necessarily based on the WINDOW clause . The WINDOW clause is optional and can be used to... - https://man.mtool.work/duckdb/2.0/sql/query_syntax/qualify.html
- Schema 9652
- Types It is important to use the correct type for encoding columns (e.g., BIGINT , DATE , DATETIME ). While it is always possible to use string types ( VARCHAR , etc.) to encode more specific values, this is not recommended. Strings use mor
...e space and are slower to process in operations such as filtering, join, and aggregation. When loading CSV files, you may leverage the CSV reader's auto-detection mechanism to determine th...y 242.0 s For this dataset, primary keys will only have a (small) positive effect on highly selective queries such as when filtering on a single identifier. Defining primary keys (or indexes) will not have an effect on join and aggregation operators. Best... - https://man.mtool.work/duckdb/2.0/guides/performance/schema.html
- SAMPLE Clause 9193
- The SAMPLE clause allows you to run the query on a sample from the base table. This can significantly speed up processing of queries, at the expense of accuracy in the result. Samples can also be used to quickly see a snapshot of the data w
...r the WHERE , GROUP BY , HAVING , and QUALIFY clauses, and before ORDER BY and LIMIT . So it is written after grouping and filtering, but it is applied to the result of the FROM clause before those operations run. To sample an individual table expression... - https://man.mtool.work/duckdb/2.0/sql/query_syntax/sample.html
- Command Line Client 8496
- Installation To use the DuckDB CLI client, visit the CLI installation page . The latest stable version of the DuckDB command line client is 2.0.0. Installation The DuckDB CLI (Command Line Interface) is a single, dependency-free executable.
...ess bar displays an estimated time remaining until completion. This feature employs advanced statistical modeling ( Kalman filtering ) to deliver more accurate predictions than simple linear extrapolation. How It Works DuckDB calculates the estimated time...s Monitoring: DuckDB's internal progress API reports the estimated completion percentage for the running query Statistical Filtering: A Kalman filter smooths noisy progress measurements and accounts for execution variability Continuous Refinement: The sys... - https://man.mtool.work/duckdb/2.0/clients/cli/overview.html
- Spatial Functions 8275
- Function Index Scalar Functions Function Summary DuckDB_PROJ_Compiled_Version Returns a text description of the PROJ library version that this instance of DuckDB was compiled against. DuckDB_Proj_Version Returns a text description of the PR
...the point(s) at the geometry with the given measure ST_LocateBetween Returns a geometry or geometry collection created by filtering and interpolating vertices within a range of "M" values ST_M Returns the M coordinate of a point geometry ST_MMax Returns...(line GEOMETRY, start_measure DOUBLE, end_measure DOUBLE) Description Returns a geometry or geometry collection created by filtering and interpolating vertices within a range of "M" values Creates a geometry or geometry collection, containing the parts fo...able function will only return rows that intersect with the given WKB geometry. Some drivers may support efficient spatial filtering natively, in which case it will be pushed down. Otherwise the filtering is done by GDAL which may be much slower. open_opt... - https://man.mtool.work/duckdb/2.0/core_extensions/spatial/functions.html
- Timestamp Issues 8275
- Timestamp with Time Zone Promotion Casts Working with time zones in SQL can be quite confusing at times. For example, when filtering to a date range, one might try the following query: SET timezone = 'America/Los_Angeles'; CREATE TABLE time
... - https://man.mtool.work/duckdb/2.0/guides/sql_features/timestamps.html
- Querying Parquet Metadata 8038
- Parquet Metadata The parquet_metadata function can be used to query the metadata contained within a Parquet file, which reveals various internal details of the Parquet file such as the statistics of the different columns. This can be useful
...LE VARCHAR BLOB The parquet_bloom_probe(filename, column_name, value) function shows which row groups can be excluded when filtering for a given value of a given column using the Bloom filter. For example: FROM parquet_bloom_probe('my_file.parquet', 'my_c... - https://man.mtool.work/duckdb/2.0/data/parquet/metadata.html
- SQL on Apache Arrow 8038
- DuckDB can query multiple different types of Apache Arrow objects. DuckDB pushes the filters of a query that it can translate, such as comparisons, into the scan of an Arrow dataset. Arrow tables, record batches, scanners and RecordBatchRea
...also be queried as if they were regular tables. Scanners read over a dataset and select specific columns or apply row-wise filtering. This is similar to how DuckDB pushes column selections and filters down into an Arrow Dataset, but using Arrow compute op... - https://man.mtool.work/duckdb/2.0/guides/python/sql_on_arrow.html
- Window Functions 8038
- DuckDB supports window functions , which can use multiple rows to calculate a value for each row. Window functions are blocking operators , i.e., they require their entire input to be buffered, making them one of the most memory-intensive o
...BY , etc. For more complex queries you can find where WINDOW clauses fall in the canonical order of the SELECT statement . Filtering the Results of Window Functions Using QUALIFY Window functions are executed after the WHERE and HAVING clauses have been a...to filter the results of window functions The QUALIFY clause avoids the need for a subquery or WITH clause to perform this filtering. Box and Whisker Queries All aggregates can be used as windowing functions, including the complex statistical functions. T... - https://man.mtool.work/duckdb/2.0/sql/functions/window_functions.html
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