Results of 1 - 10 of about 20 for generally (0.002 sec.)
- Subqueries 12048
- Subqueries are parenthesized query expressions that appear as part of a larger, outer query. Subqueries are usually based on SELECT ... FROM , but in DuckDB other query constructs such as PIVOT can also appear as a subquery. Scalar Subquery
...ubquery. It returns either true when the subquery returns one or more records, and false otherwise. The EXISTS operator is generally the most useful as a correlated subquery to express semijoin operations. However, it can be used as an uncorrelated subque...ubquery. It returns either true when the subquery returns an empty result, and false otherwise. The NOT EXISTS operator is generally the most useful as a correlated subquery to express antijoin operations. For example, to find Person nodes without an inte... - https://man.mtool.work/duckdb/2.0/sql/expressions/subqueries.html
- Multiple Connections 10791
- For tests whose purpose is to verify that the transactional management or versioning of data works correctly, it is generally necessary to use multiple connections. For example, if we want to verify that the creation of tables is correctly
... - https://man.mtool.work/duckdb/2.0/dev/sqllogictest/multiple_connections.html
- Versioning of Extensions 10791
- Extension Versioning Most software has some sort of version number. Version numbers serve a few important goals: Tie a binary to a specific state of the source code Allow determining the expected feature set Allow determining the state of t
...re about the release cycle of a specific extension, refer to the documentation or GitHub page of the respective extension. Generally, pre-release and stable extensions will document their releases as GitHub releases, an example of which you can see in the...extensions were separated into their own repository, which we call out-of-tree. While from a user's perspective, there are generally no noticeable differences, there are some minor differences related to versioning: in-tree extensions use the version of D... - https://man.mtool.work/duckdb/2.0/extensions/versioning_of_extensions.html
- Typecasting 10791
- Typecasting is an operation that converts a value in one particular data type to the closest corresponding value in another data type. Like other SQL engines, DuckDB supports both implicit and explicit typecasting. Explicit Casting Explicit
...function but can be cast to the required type. Implicit casts can only be added for a number of type combinations, and is generally only possible when the cast cannot fail. For example, an implicit cast can be added from INTEGER to DOUBLE – but not from...nerate_typecasting_matrix.py ; do not edit it by hand. Implicit casts are added by the system only where the conversion is generally lossless, so they are also safe to reverse, with the notable exception of casts from wide integer or DECIMAL types to FLOA... - https://man.mtool.work/duckdb/2.0/sql/data_types/typecasting.html
- Concurrency 10179
- 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
...was released alongside DuckDB 2.0. Optimistic Concurrency Control DuckDB uses optimistic concurrency control , an approach generally considered to be the best fit for read-intensive analytical database systems as it speeds up read query processing. As a r... - https://man.mtool.work/duckdb/2.0/connect/concurrency.html
- Release Cycle 9550
- 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>.<
...start off by listing the format these core branches come in. main branch: the main branch can mean various things, but can generally be considered the catch-all branch vx.y-codename branch: the branch used to produce all vx.y.z releases vx.y.z tag: a stab...hould be available. For unstable API extensions, this means a rebuild of the binaries. For the core extensions, this build generally happens through the duckdb/duckdb CI. This means that the list of extensions that will be available on release is document... - https://man.mtool.work/duckdb/2.0/dev/release_cycle.html
- Writing Tests 8921
- Development and Testing It is crucial that any new features that get added have correct tests that not only test the “happy path”, but also test edge cases and incorrect usage of the feature. In this section, we describe how DuckDB tests ar
...written using the Catch framework . Client Connector Tests DuckDB also has tests for various client connectors. These are generally written in the relevant client language, and can be found in tools/*/tests . They also double as documentation of what sho... - https://man.mtool.work/duckdb/2.0/dev/sqllogictest/writing_tests.html
- Timestamp Issues 8921
- 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
...use plain TIMESTAMP s for temporal data. This will avoid confusing issues such as this, and the arithmetic operations are generally faster. Time Zone Performance DuckDB's time zone support is provided by the icu extension . Starting with DuckDB 2.0, the... - https://man.mtool.work/duckdb/2.0/guides/sql_features/timestamps.html
- Partitioned Writes 8292
- Examples Write a table to a Hive partitioned dataset of Parquet files: COPY orders TO 'orders' (FORMAT parquet, PARTITION_BY (year, month)); Write a table to a Hive partitioned dataset of CSV files, allowing overwrites: COPY orders TO 'orde
...100): SET partitioned_write_max_open_files = 10; Bestpractice Writing data into many small partitions is expensive. It is generally recommended to have at least 100 MB of data per partition. Filename Pattern By default, files will be named data_0.parquet... - https://man.mtool.work/duckdb/2.0/data/partitioning/partitioned_writes.html
- Benchmark Suite 8292
- DuckDB has an extensive benchmark suite. When making changes that have potential performance implications, it is important to run these benchmarks to detect potential performance regressions. Getting Started To build the benchmark suite, ru
...s of rows per partition) * The error rate (fraction of the values that are missing) * The number of partitions. Benchmarks generally require some data preparation before running the query. Data preparation is done in the load section of the benchmark file... - https://man.mtool.work/duckdb/2.0/dev/benchmark.html
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