Results of 1 - 10 of about 22 for ordering (0.003 sec.)
- Window Functions 13938
- 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
...urpose Window Functions The table below shows the available general window functions. Name Description cume_dist([ORDER BY ordering]) The cumulative distribution: (number of partition rows preceding or peer with current row) / total partition rows. dense..._rank() The rank of the current row without gaps; this function counts peer groups. fill(expr [ ORDER BY ordering]) Fill in missing values using linear interpolation with ORDER BY as the X-axis. first_value(expr[ ORDER BY ordering][ IGN...st row (with a non-null value of expr if IGNORE NULLS is set) of the window frame. lag(expr[, offset[, default]][ ORDER BY ordering][ IGNORE NULLS]) Returns expr evaluated at the row that is offset rows (among rows with a non-null value of expr if IGNORE... - https://man.mtool.work/duckdb/2.0/sql/functions/window_functions.html
- Aggregate Functions 13349
- Examples Produce a single row containing the sum of the amount column: SELECT sum(amount) FROM sales; Produce one row per unique region, containing the sum of amount for each group: SELECT region, sum(amount) FROM sales GROUP BY region; Ret
...function call. Note the lack of the comma separator before the clause. SELECT ⟨aggregate_function⟩(⟨arg⟩, ⟨sep⟩ ORDER BY ⟨ordering_criteria⟩); This clause ensures that the values being aggregated are sorted before applying the function. Most aggregate f...s parsed and discarded. However, there are some order-sensitive aggregates that can have non-deterministic results without ordering, e.g., first , last , list and string_agg / group_concat / listagg . These can be made deterministic by ordering the argum...te functions. Function Description any_value(arg) Returns the first non-null value from arg . This function is affected by ordering . arg_max(arg, val) Finds the row with the maximum val and calculates the arg expression at that row. Rows where the value... - https://man.mtool.work/duckdb/2.0/sql/functions/aggregates.html
- Indexing 8737
- 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
...r value (e.g., it can omit a block with a min-max range of 1000 to 2000 when comparing for = 123 or < 400 ). The Effect of Ordering on Zonemaps The more ordered the data within a column, the more valuable the zonemap indexes will be. For example, a colum...pecific columns with selective filters, it is best to pre-order data by those columns when inserting it. Even an imperfect ordering will still be helpful. The best case of ordered data commonly arises with DATETIME columns. Microbenchmark: The Effect of...smaller storage size. It also allows the computation to be 1.5× faster. Ordered Integers Another practical way to exploit ordering is to use the INTEGER type with automatic increments rather than UUID for columns queried using selective filters. In a sc... - https://man.mtool.work/duckdb/2.0/guides/performance/indexing.html
- Pragmas 8299
- The PRAGMA statement is a SQL extension adopted by DuckDB from SQLite. PRAGMA statements can be issued in a similar manner to regular SQL statements. PRAGMA commands may alter the internal state of the database engine, and can influence the
...ions: PRAGMA collations; Set the default collation to one of the available ones: SET default_collation = 'nocase'; Default Ordering for NULLs Set the default ordering for NULLs to be either NULLS_FIRST , NULLS_LAST , NULLS_FIRST_ON_ASC_LAST_ON_DESC or NU...default_null_order = 'NULLS_FIRST'; SET default_null_order = 'NULLS_LAST_ON_ASC_FIRST_ON_DESC'; Set the default result set ordering direction to ASCENDING or DESCENDING : SET default_order = 'ASCENDING'; SET default_order = 'DESCENDING'; Ordering by Non-...Integer Literals By default, ordering by non-integer literals is not allowed: SELECT 42 ORDER BY 'hello world'; -- Binder Error: ORDER BY non-integer literal ha... - https://man.mtool.work/duckdb/2.0/configuration/pragmas.html
- Non-Deterministic Behavior 8248
- Several operators in DuckDB exhibit non-deterministic behavior. Most notably, SQL uses set semantics, which allows results to be returned in a different order. DuckDB exploits this to improve performance, particularly when performing multi-
...Other factors, such as using different compilers, operating systems and hardware architectures, can also cause changes in ordering. This page documents the cases where non-determinism is an expected behavior . If you would like to make your queries dete...rounds: Limit the number of threads to prevent non-determinism introduced by multi-threading. sql SET threads = 1; Enforce ordering. For example, you can use the ORDER BY ALL clause : sql SELECT * FROM ( SELECT 'A' AS x UNION SELECT 'B' AS x ) ORDER BY A... - https://man.mtool.work/duckdb/2.0/operations_manual/non-deterministic_behavior.h...
- Array Type 8164
- An ARRAY column stores fixed-sized arrays. All fields in the column must have the same length and the same underlying type. Arrays are typically used to store arrays of numbers, but can contain any uniform data type, including ARRAY , LIST
...FROM x, y WHERE x.i = y.i; Compute cosine similarity: SELECT array_cosine_similarity(x.v, y.v) FROM x, y WHERE x.i = y.i; Ordering The ordering of ARRAY instances is defined using a lexicographical order. NULL values compare greater than all other value... - https://man.mtool.work/duckdb/2.0/sql/data_types/array.html
- List Type 8114
- A LIST column encodes lists of values. Fields in the column can have values with different lengths, but they must all have the same underlying type. LIST s are typically used to store arrays of numbers, but can contain any uniform data type
...][:2] ['a', 'b'] SELECT ['a', 'b', 'c'][-2:] ['b', 'c'] SELECT list_slice(['a', 'b', 'c'], 2, 3) ['b', 'c'] Comparison and Ordering The LIST type can be compared using all the comparison operators . These comparisons can be used in logical expressions su...ch as WHERE and HAVING clauses, and return BOOLEAN values . The LIST ordering is defined positionally using the following rules, where min_len = min(len(l1), len(l2)) . Equality. l1 and l2 are equal,... - https://man.mtool.work/duckdb/2.0/sql/data_types/list.html
- Variant Functions 7979
- This section describes functions that operate on the VARIANT type . New Most variant_* functions were introduced in DuckDB 2.0. The variant_extract , variant_normalize and variant_typeof functions were already available in DuckDB 1.5. Name
...tained in the haystack VARIANT . variant_comparator(v) Return a binary sort key that orders a VARIANT value by the logical ordering of VARIANT values. variant_normalize(v) Return a canonical representation of a VARIANT value, so that values representing...iant_comparator(v) | Description | Return a binary sort key (a BLOB ) that orders a VARIANT value according to the logical ordering of VARIANT values. This is used internally so that VARIANT s compare and sort consistently with the corresponding native D... - https://man.mtool.work/duckdb/2.0/sql/functions/variant.html
- Write User Defined Functions 7929
- Overview The Rust client can register user-defined functions written in Rust: scalar functions with the vscalar feature and table functions with the vtab feature. Both operate on DuckDB's columnar data chunks, so a single call processes a b
...alTypeHandle, LogicalTypeId}, vtab::{BindInfo, InitInfo, TableFunctionInfo, VTab}, }; use std::sync::atomic::{AtomicUsize, Ordering}; struct Numbers; // Computed once from the call's arguments; read-only during execution. struct NumbersBind { count: usiz...at most a vector's worth of rows. let capacity = output.flat_vector(0).capacity(); let start = cursor.fetch_add(capacity, Ordering::Relaxed); if start >= count { output.set_len(0); // no more rows: end the scan return Ok(()); } let rows = capacity.min(c... - https://man.mtool.work/duckdb/2.0/clients/rust/functions.html
- Interval Type 7929
- INTERVAL s represent periods of time that can be added to or subtracted from DATE , TIMESTAMP , TIMESTAMPTZ , or TIME values. Name Description INTERVAL Period of time An INTERVAL can be constructed by providing amounts together with units.
...'day', TIMESTAMP '2020-01-02 00:00:00' - TIMESTAMP '2020-01-01 01:00:00'), -- 0 ; Equality and Comparison For equality and ordering comparisons only, the total number of microseconds in an INTERVAL is computed by converting the days basis unit to 24 * 60...* 60 * 60 * 1e6 microseconds. As a result, INTERVAL s can compare equal even when they are functionally different, and the ordering of INTERVAL s is not always preserved when they are added to dates or timestamps. For example: INTERVAL 30 DAYS = INTERVAL... - https://man.mtool.work/duckdb/2.0/sql/data_types/interval.html
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