Results of 1 - 10 of about 24 for multi (0.003 sec.)
- Non-Deterministic Behavior 13377
- 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-
...', NULL, NULL]) AS arr; For this query, both [A, B] and [B, A] are valid results. Floating-Point Aggregate Operations with Multi-Threading Floating-point inaccuracies may produce different results when run in multi-threaded configurations: For example...s; The expected standard deviations and correlations from this query are 0 for all values of s . However, when executed on multiple threads, the query may return small numbers ( 0 <= z < 10e-16 ) due to floating-point inaccuracies. Working Around Non-...rable. In these cases, try the following workarounds: 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 ( S... - https://man.mtool.work/duckdb/2.0/operations_manual/non-deterministic_behavior.h...
- Spatial Functions 13194
- 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
...of geometries into a collection geometry. ST_CollectionExtract Extracts geometries from a GeometryCollection into a typed multi geometry. ST_ConcaveHull Returns the 'concave' hull of the input geometry, containing all of the source input's points, an...s a GEOMETRY_TYPE enum identifying the input geometry type. Possible enum return types are: POINT , LINESTRING , POLYGON , MULTIPOINT , MULTILINESTRING , MULTIPOLYGON and GEOMETRYCOLLECTION . ST_HasM Check if the input geometry has M values. ST_HasZ C...polatePoint Returns a point interpolated along a line at a fraction of total 2D length. ST_LineInterpolatePoints Returns a multi-point interpolated along a line at a fraction of total 2D length. ST_LineLocatePoint Returns the location on a line closes... - https://man.mtool.work/duckdb/2.0/core_extensions/spatial/functions.html
- Crashes 10225
- DuckDB is thoroughly tested via an extensive test suite. However, bugs can still occur and these can sometimes lead to crashes. This page contains practical information on how to troubleshoot DuckDB crashes. Types of Crashes There are a few
...ying another computer to run the same workload. Decomposing the Query It's a good idea to try to break down the query into multiple smaller queries with each using a separate DuckDB extension and SQL feature. For example, if you have a query that targ...the dataset's files manually and load them into DuckDB. Then perform the first join and the second join separately. If the multi-step approach still exhibits the crash at some step, then the query that triggers the crash is a good basis for a minimal...reproducible example. If the multi-step approach works and the multi-step process no longer crashes, try to reconstruct the original query and observe which... - https://man.mtool.work/duckdb/2.0/guides/troubleshooting/crashes.html
- Catalogs 8924
- The iceberg extension supports attaching Iceberg REST Catalogs. Attaching a catalog is required for writing to Iceberg . Before attaching an Iceberg REST Catalog, you must install the iceberg extension by following the instructions located
...these catalogs. Catalog behavior Option to set Does not support staged CREATE TABLE STAGE_CREATE_TABLES false Rejects the multi-table transactions/commit endpoint DISABLE_MULTI_TABLE_COMMIT true Fully initializes metadata on CREATE TABLE and rejects...anup: ATTACH '⟨warehouse⟩' AS horizon_catalog ( TYPE iceberg, URI '⟨catalog_endpoint⟩', STAGE_CREATE_TABLES false, DISABLE_MULTI_TABLE_COMMIT true, SKIP_CREATE_TABLE_METADATA_UPDATES true, REMOVE_FILES_ON_DELETE false ); Limitations DuckDB supports Ic... - https://man.mtool.work/duckdb/2.0/core_extensions/iceberg/catalogs.html
- Julia Client 8740
- The DuckDB Julia package provides a high-performance front-end for DuckDB. Much like SQLite, DuckDB runs in-process within the Julia client, and provides a DBInterface front-end. The package also supports multi-threaded execution. It uses J
...ulia threads/tasks for this purpose. If you wish to run queries in parallel, you must launch Julia with multi-threading support (by e.g., setting the JULIA_NUM_THREADS environment variable). Installation Install DuckDB as follows: u...nterface.execute(con, "SELECT 42 a") print(results) Some SQL statements, such as PIVOT and IMPORT DATABASE are executed as multiple prepared statements and will error when using DuckDB.execute() . Instead they can be run with DuckDB.query() instead of... - https://man.mtool.work/duckdb/2.0/clients/tertiary_clients/julia.html
- Release Cycle 8740
- This document outlines the DuckDB and core extension release cycle framework. It is intended for developers working on DuckDB extensions to better understand the underlying processes. Overview DuckDB follows Semantic Versioning ( v<MAJOR>.<
...e branch this is always main. This means all other branches of format vx.y-codename must be vx.<y-n>-codename where n >= 1 Multi branch extension : Extension with more than 1 active branch Two branch extension : Extension with two active branches: mai...table extension API. This can be both the C++ API or the unstable C API. These extensions are not binary-compatible across multiple DuckDB versions Stable API extension : An extension targeting the stable C API of DuckDB. These extensions are binary-c...ompatible across multiple DuckDB versions In-tree extensions : Extensions that live inside the duckdb/duckdb source tree Main Branches and Tags I... - https://man.mtool.work/duckdb/2.0/dev/release_cycle.html
- Samples 8373
- Samples are used to randomly select a subset of a dataset. Examples Select a sample of exactly 5 rows from tbl using reservoir sampling: SELECT * FROM tbl USING SAMPLE 5; Select a sample of approximately 10% of the table using system sampli
...between runs unless the seed is specifically specified. Specifying the seed only guarantees that the sample is the same if multi-threading is not enabled (i.e., SET threads = 1 ). In the case of multiple threads running over a sample, samples are not...ed above, fixing the seed only guarantees a reproducible sample when DuckDB runs single-threaded ( SET threads = 1 ). With multiple threads, samples are not necessarily consistent even with a fixed seed. Sampling Methods reservoir Reservoir sampling i...higher the performance hit incurred by this process. Reservoir sampling also incurs an additional performance penalty when multi-processing is used, since the reservoir is to be shared amongst the different threads to ensure unbiased sampling. This is... - https://man.mtool.work/duckdb/2.0/sql/samples.html
- Transaction Management 8190
- DuckDB supports ACID database transactions . Transactions provide isolation, i.e., changes made by a transaction are not visible from concurrent transactions until it is committed. A transaction can also be aborted, which discards any chang
...ch has an identical behavior: ABORT; If you are not in an active transaction, the ROLLBACK and ABORT statements will fail. Multi-Statement Transactions When multiple SQL statements are submitted together (e.g., separated by semicolons), they are execu... - https://man.mtool.work/duckdb/2.0/sql/statements/transactions.html
- Concurrency 8006
- Handling Concurrency Single Process In in-process mode, DuckDB has two configurable options for concurrency: Read-write mode: one process can both read and write to the database. Read-only mode: multiple processes can read from the database
..., but no processes can write ( access_mode = 'READ_ONLY' ). When using read-write mode, DuckDB supports multiple writer threads using a combination of MVCC (Multi-Version Concurrency Control) and optimistic concurrency control (see...DB supports concurrency within a single process according to the following rules. As long as there are no write conflicts, multiple concurrent writes will succeed. Appends will never conflict, even on the same table. Multiple threads can also simultan...) the same row at the same time. In that situation, the second thread to attempt the edit will fail with a conflict error. Multiple Processes Writing to DuckDB's native database format from multiple processes is supported through the Quack remote prot... - https://man.mtool.work/duckdb/2.0/connect/concurrency.html
- ODBC Extension 8006
- Please note that DuckDB also offers an ODBC client , which allows you to connect to DuckDB via ODBC from other applications. The odbc_scanner extension allows connecting to other databases (using their ODBC drivers ) and run queries with th
...ied to the prepared statement and will be freed when the statement is destroyed. Connections and Concurrency DuckDB uses a multi-threaded execution engine to run parts of the query in parallel. ODBC drivers may or may not support using the same connec...hreads concurrently. To prevent possible concurrency problems the extension does not allow to use the same connection from multiple threads. For example, the following query: FROM odbc_query(getvariable('conn'), 'SELECT ''foo'' col1 FROM DUAL') UNION...nput Error: 'odbc_query' error: ODBC connection not found on global init, id: 139760181976192 This can be avoided by using multiple ODBC connections: FROM odbc_query(getvariable('conn1'), 'SELECT ''foo'' col1 FROM DUAL') UNION ALL FROM odbc_query(getv... - https://man.mtool.work/duckdb/2.0/core_extensions/odbc/overview.html
DuckDB 2.0 Documentation / man.mtool.work