Results of 1 - 10 of about 17 for reduce (0.002 sec.)
- Lambda Functions 14966
- DuckDB lambda functions (a.k.a. 'lambdas' or 'lambda expressions') are expressions that define an inline anonymous function. Lambdas are passed as argument to certain list functions , which evaluate the passed lambda expression against its
...form . array_apply(list, lambda(x)) Alias for list_transform . array_filter(list, lambda(x)) Alias for list_filter . array_reduce(list, lambda(x,y)[, initial_value]) Alias for list_reduce . array_transform(list, lambda(x)) Alias for list_transform . fi...on's return type to BOOL . The return type of list_filter is the same as the input list's. See list_filter examples . list_reduce(list, lambda(x,y)[, initial_value]) Reduces all elements of the input list into a single scalar value by executing the lam...nction on a running result and the next list element. The lambda function has an optional initial_value argument. See list_reduce examples . list_transform(list, lambda(x)) Returns a list that is the result of applying the lambda function to each eleme... - https://man.mtool.work/duckdb/2.0/sql/functions/lambda.html
- Out-of-Memory Issues 10035
- Configuration Options If you are experiencing out-of-memory issues with DuckDB, try tweaking the following configuration options: Reduce the number of threads using the SET threads = ... command. Setting the memory limit lower than the defa
...= false; Schema and Indexes If you run in a memory-constrained environment, using smaller data types (e.g., TINYINT ) can reduce the amount of memory and disk space required to complete a query. DuckDB's bitpacking compression means small values store...up more memory during processing – hence, using the most restrictive types possible when creating columns is necessary to reduce memory consumption. Indexes can significantly increase memory consumption. Additionally, they are currently not buffer-man... - https://man.mtool.work/duckdb/2.0/guides/performance/oom.html
- List Functions 9569
- Function Description list[index] Extracts a single list element using a (1-based) index . list[begin[:end][:step]] Extracts a sublist using slice conventions . Negative values are accepted. list1 && list2 Alias for list_has_any . list1 <->
.... array_push_back(list, element) Alias for list_append . array_push_front(list, element) Prepends element to list . array_reduce(list, lambda(x,y)[, initial_value]) Alias for list_reduce . array_resize(list, size[[, value]]) Alias for list_resize . ar...prepend(element, list) Prepends element to list . list_product(list) Applies aggregate function product to the list . list_reduce(list, lambda(x,y)[, initial_value]) Reduces all elements of the input list into a single scalar value by executing the lam...nction on a running result and the next list element. The lambda function has an optional initial_value argument. See list_reduce examples . list_resize(list, size[[, value]]) Resizes the list to contain size elements. Initializes new elements with val... - https://man.mtool.work/duckdb/2.0/sql/functions/list.html
- SQLSmith Extension 8845
- The sqlsmith extension is used for testing. Installing and Loading INSTALL AND LOAD sqlsmith; Functions The sqlsmith extension registers the following functions: sqlsmith fuzzyduck reduce_sql_statement fuzz_all_functions
... - https://man.mtool.work/duckdb/2.0/core_extensions/sqlsmith.html
- Schema 8448
- 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
...orrect types for CSV inputs. If you run in a memory-constrained environment, using smaller data types (e.g., TINYINT ) can reduce the amount of memory and disk space required to complete a query. DuckDB's bitpacking compression means small values store...up more memory during processing – hence, using the most restrictive types possible when creating columns is necessary to reduce memory consumption. Microbenchmark: Using Timestamps We illustrate the difference in aggregation speed using the creationD... - https://man.mtool.work/duckdb/2.0/guides/performance/schema.html
- Text Types 8207
- In DuckDB, strings can be stored in the VARCHAR field. The field allows storage of Unicode characters. Internally, the data is encoded as UTF-8. Name Aliases Description VARCHAR CHAR , BPCHAR , STRING , TEXT Variable-length character string
...RING and TEXT types is not required and has no effect on the system. Specifying the length will not improve performance or reduce storage space of the strings in the database. These variants are supported for compatibility with other systems that do re... - https://man.mtool.work/duckdb/2.0/sql/data_types/text.html
- UNPIVOT Statement 8207
- The UNPIVOT statement allows multiple columns to be stacked into fewer columns. In the basic case, multiple columns are stacked into two columns: a NAME column (which contains the name of the source column) and a VALUE column (which contain
...tatement has additional flexibility: more than 2 destination columns are supported. This can be useful when the goal is to reduce the extent to which a dataset is pivoted, but not completely stack all pivoted columns. To demonstrate this, the query bel...tatement has additional flexibility: more than 2 destination columns are supported. This can be useful when the goal is to reduce the extent to which a dataset is pivoted, but not completely stack all pivoted columns. To demonstrate this, the query bel... - https://man.mtool.work/duckdb/2.0/sql/statements/unpivot.html
- Tuning Workloads 8138
- DuckDB aims to perform well out of the box, so most workloads do not require any tuning. When tuning is worthwhile, there is no single configuration or magic number that is optimal for every workload: the right settings depend on what you a
...download the data it actually needs. Apply filters on remote Parquet files when possible. DuckDB can use these filters to reduce the amount of data that is scanned. Either sort or partition data by columns that are regularly used for filters: this inc...the same database connection many times. Disconnecting and reconnecting on every query will incur some overhead, which can reduce performance when running many small queries. DuckDB also caches some data and metadata in memory, and that cache is lost w... - https://man.mtool.work/duckdb/2.0/guides/performance/how_to_tune_workloads.html
- Order Preservation 8052
- For many operations, DuckDB preserves the order of rows, similarly to data frame libraries such as Pandas. Example Take the following table for example: CREATE TABLE tbl AS SELECT * FROM (VALUES (1, 'a'), (2, 'b'), (3, 'c')) t(x, y); SELECT
...e order should be preserved. To change this setting, use: SET preserve_insertion_order = false; Disabling this setting can reduce memory usage when importing or exporting datasets larger than memory. See the preserve_insertion_order option in the workl... - https://man.mtool.work/duckdb/2.0/sql/dialect/order_preservation.html
- JSON Processing Functions 7897
- JSON Extraction Functions There are two extraction functions, which have their respective operators. The operators can only be used if the string is stored as the JSON logical type. These functions support the same two location notations as
...OSE, SWAN, NULL] To drop the NULL entries and combine the remaining names into a single string, chain list_filter and list_reduce : SELECT list_reduce( list_filter(j->>'$.species[*]', lambda s: s IS NOT NULL), lambda acc, s: acc || ', ' || s ) AS names... - https://man.mtool.work/duckdb/2.0/data/json/json_functions.html
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