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- Expressions 12010
- An expression is a combination of values, operators and functions. Expressions are highly composable, and range from very simple to arbitrarily complex. They can be found in many different parts of SQL statements. This section describes the
... - https://man.mtool.work/duckdb/2.0/sql/expressions/overview.html
- Parquet Tips 11620
- 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
...e as the number of CPU threads used to query that file. More row groups beyond the 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 fi...t you filter on most often before writing makes these min/max ranges tight and non-overlapping between row groups, so that highly selective queries on those columns scan far fewer row groups: COPY (FROM 'events.parquet' ORDER BY event_time) TO 'events-... - https://man.mtool.work/duckdb/2.0/data/parquet/tips.html
- Indexing 10860
- 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
...ecause of index maintenance for these operations. For some use cases, single-column ART indexes improve the performance of highly selective queries using the indexed column. An ART index does not affect the performance of join, aggregation, and sorting...constraints, if these are necessary for enforcing constraints on your data. Do not define explicit indexes unless you have highly selective queries and enough memory available. If you define an ART index, do so after bulk loading the data to the table.... - https://man.mtool.work/duckdb/2.0/guides/performance/indexing.html
- Jupyter Notebooks 9692
- DuckDB's Python client can be used directly in Jupyter notebooks with no additional configuration, as the first section shows. Additional libraries can simplify SQL query development; the rest of this guide uses the JupySQL package. See oth
...using Pandas and then use matplotlib or seaborn for plotting. This approach requires loading all data into memory which is highly inefficient. The plotting module in JupySQL runs computations in the SQL engine. This delegates memory management to the e...distance --bins 10 --with short_trips Summary You now have the ability to alternate between SQL and Pandas in a simple and highly performant way! You can plot massive datasets directly through the engine (avoiding both the download of the entire file a... - https://man.mtool.work/duckdb/2.0/guides/python/jupyter.html
- Spatial Functions 8932
- 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
...ers. This function uses the GeographicLib library, calculating the area using an ellipsoidal model of the earth. This is a highly accurate method for calculating the area of a polygon taking the curvature of the earth into account, but is also the slow...inverse geodesic problem , calculating the distance between two points using an ellipsoidal model of the earth. This is a highly accurate method for calculating the distance between two arbitrary points taking the curvature of the earths surface into...inverse geodesic problem , calculating the distance between two points using an ellipsoidal model of the earth. This is a highly accurate method for calculating the distance between two arbitrary points taking the curvature of the earths surface into... - https://man.mtool.work/duckdb/2.0/core_extensions/spatial/functions.html
- Describe 8932
- Describing a Table To view the schema of a table, use the DESCRIBE statement (or its alias DESC ) followed by the table name. CREATE TABLE tbl (i INTEGER PRIMARY KEY, j VARCHAR); DESCRIBE tbl; column_name column_type null key default extra
...ULL NULL cnt_damn_it_jim_quote BIGINT YES NULL NULL NULL cnt_im_givin_her_all_shes_got_quote BIGINT YES NULL NULL NULL cnt_highly_illogical_quote BIGINT YES NULL NULL NULL bool_enterprise_saved_the_day BIGINT YES NULL NULL NULL... - https://man.mtool.work/duckdb/2.0/guides/meta/describe.html
- Querying Parquet Metadata 7782
- 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
...standalone function. Bloom Filters DuckDB supports Bloom filters for pruning the row groups that need to be read to answer highly selective queries. Currently, Bloom filters are supported for the following types: Integer types: TINYINT , UTINYINT , SMA... - https://man.mtool.work/duckdb/2.0/data/parquet/metadata.html
- Schema 7782
- 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
...ithout primary key then add primary key 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 effec... - https://man.mtool.work/duckdb/2.0/guides/performance/schema.html
- Indexes 7782
- Index Types DuckDB has two built-in index types. Indexes can also be defined via extensions . Min-Max Index (Zonemap) A min-max index (also known as zonemap or block range index) is automatically created for columns of all general-purpose d
...ix Tree (ART) An Adaptive Radix Tree (ART) is mainly used to ensure primary key constraints and to speed up point and very highly selective (i.e., < 0.1%) queries. ART indexes can be created manually using the CREATE INDEX clause and they are automatic... - https://man.mtool.work/duckdb/2.0/sql/indexes.html
- R-Tree Indexes 7004
- The spatial extension provides support for spatial indexing through the R-tree extension index type. Why Should I Use an R-Tree Index? When working with geospatial datasets, it is very common that you want to filter rows based on their spat
...N my_table USING RTREE (geom) WITH (max_node_capacity = 16); The impact tweaking these options will have on performance is highly dependent on the system setup DuckDB is running on, the spatial distribution of the dataset and the query patterns of your... - https://man.mtool.work/duckdb/2.0/core_extensions/spatial/r-tree_indexes.html
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