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- Overview of DuckDB Internals 13335
- Tip For a detailed explanation of DuckDB internals, see the Design and Implementation of DuckDB Internals ("DiDi") library entry. On this page is a brief description of the internals of the DuckDB engine. Parser The parser converts a query
...Common Sub Expressions : Extracts common subexpressions from projection and filter nodes to prevent unnecessary duplicate execution. In Clause Rewriter : Rewrites large static IN clauses to a MARK join or INNER join. Column Binding Resolver The column bi...table into BoundReferenceExpression nodes that refer to a specific index into the DataChunks that are passed around in the execution engine. Physical Plan Generator The physical plan generator converts the resulting logical operator tree into a PhysicalOp...erator tree. Execution In the execution phase, the physical operators are executed to produce the query result. DuckDB uses a push-based vectoriz... - https://man.mtool.work/duckdb/2.0/internals/overview.html
- Command Line Client 11939
- Installation To use the DuckDB CLI client, visit the CLI installation page . The latest stable version of the DuckDB command line client is 2.0.0. Installation The DuckDB CLI (Command Line Interface) is a single, dependency-free executable.
.../or commands to execute. After running the commands in the file, control will revert back to the terminal. Output from the execution of that file is governed by the same .output and .once commands that have been discussed previously. This allows the outpu...y Completion ETA DuckDB's CLI now provides intelligent time-to-completion estimates for running queries and displays total execution time upon completion. When executing queries in the DuckDB CLI, the progress bar displays an estimated time remaining unti...rcentage for the running query Statistical Filtering: A Kalman filter smooths noisy progress measurements and accounts for execution variability Continuous Refinement: The system continuously updates predicted completion time as new progress data becomes... - https://man.mtool.work/duckdb/2.0/clients/cli/overview.html
- Pragmas 10892
- 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
...subsequent execution or behavior of the engine. Configure DuckDB settings using the SET statement . You can retrieve a setting's value using SE...ual memory consumption can be higher than the specified memory limit. Threads Set the amount of threads for parallel query execution: SET threads = 4; Maximum Execution Time New As of DuckDB 2.0, the max_execution_time setting bounds the wall-clock time o...f a query in milliseconds. When the limit is exceeded, the query is aborted with the error Query exceeded maximum execution time . The default is 0 , meaning no limit. SET max_execution_time = 5000; This is a per-connection setting with a global... - https://man.mtool.work/duckdb/2.0/configuration/pragmas.html
- Execution Format 10194
- Vector is the container format used to store in-memory data during execution. DataChunk is a collection of Vectors, used for instance to represent a column list in a PhysicalProjection operator. Data Flow DuckDB uses a vectorized query execution
...ifferent physical representation . This allows for a more compressed representation, and potentially allows for compressed execution throughout the system. Below the list of supported vector formats is shown. Flat Vectors Flat vectors are physically store...dictionary compressed column segment, we store this in a dictionary vector so we can keep the data compressed during query execution. Sequence Vectors Sequence vectors are physically stored as an offset and an increment value. Sequence vectors are useful... - https://man.mtool.work/duckdb/2.0/internals/vector.html
- Prepared Statements 9859
- DuckDB supports prepared statements where parameters are substituted when the query is executed. This can improve readability and is useful for preventing SQL injections . Syntax There are three syntaxes for denoting parameters in prepared
...nts with auto-incremented indexing, i.e., the position of the parameters in the query corresponds to their position in the execution statement. For example: PREPARE query_person AS SELECT * FROM person WHERE starts_with(name, ?) AND age >= ?; Using the CL...n variables as default values for named parameters was introduced in DuckDB 2.0. When a named parameter is not supplied at execution time, DuckDB fills it from the session variable of the same name, if one is set. An explicit argument always takes precede...ted parameters still fall back to theirs: EXECUTE compute(multiplier := 3); result 126 Because the fallback is resolved at execution time, re-executing the statement after changing a variable picks up the new value: SET VARIABLE multiplier = 100; EXECUTE... - https://man.mtool.work/duckdb/2.0/sql/query_syntax/prepared_statements.html
- Relational API on Pandas 9336
- DuckDB offers a relational API that can be used to chain together query operations. These are lazily evaluated so that DuckDB can optimize their execution. These operators can act on Pandas DataFrames, DuckDB tables or views (which can poin
...R BY i DESC LIMIT 2 transformed_rel = rel.filter('i >= 2').select('i, j, i*2 AS two_i').order('i DESC').limit(2) # trigger execution by requesting .df() of the relation # .df() could have been added to the end of the chain above - it was separated for cla... - https://man.mtool.work/duckdb/2.0/guides/python/relational_api_pandas.html
- Write User Defined Functions 9161
- Overview The JDBC driver can register user-defined functions (UDFs) written in Java, including scalar functions and table functions. This page covers building and registering both, from the simple functional-interface overloads to the vecto
...The DuckDBDataChunkReader , its DuckDBReadableVector columns, and the DuckDBWritableVector are valid only during callback execution and must not be retained. Scalar Function Builder Methods The scalarFunction() builder exposes the following methods: with...Parameter() and getNamedParameter() . It may return bind data that is passed to the later callbacks. init runs once before execution and returns the global state. localInit (optional) runs once per execution thread and returns thread-local state. Override...tring() , and setNull() . All callback arguments, including the parameter and info objects, are valid only during callback execution and must not be retained. The Java table function interface mirrors DuckDB's C API table functions as closely as possible.... - https://man.mtool.work/duckdb/2.0/clients/java/functions.html
- Sirius Extension 8638
- The sirius extension is not yet available. It is coming soon. The sirius extension adds GPU-accelerated query execution to DuckDB. Sirius is a GPU-native SQL engine that runs DuckDB queries on NVIDIA GPUs.
... - https://man.mtool.work/duckdb/2.0/core_extensions/sirius.html
- Write User Defined Functions 8463
- 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
...result_column() and reads the call's arguments with get_parameter() , returning read-only bind data. init runs once before execution and returns per-scan state, such as a cursor. func produces one chunk of rows per call. It fills the output vectors and se...nteger in 0..count , over columns of increasing complexity. Its skeleton, showing the bind data, init state, and per-chunk execution model: use duckdb::{ Connection, Result, core::{DataChunkHandle, LogicalTypeHandle, LogicalTypeId}, vtab::{BindInfo, InitI...e std::sync::atomic::{AtomicUsize, Ordering}; struct Numbers; // Computed once from the call's arguments; read-only during execution. struct NumbersBind { count: usize, } // Tracks scan progress: func is called once per output chunk. struct NumbersInit {... - https://man.mtool.work/duckdb/2.0/clients/rust/functions.html
- Logging 8289
- DuckDB implements a logging mechanism that provides users with detailed information about events such as query execution, performance metrics and system events. Warning Logs may contain sensitive information, including secrets and credentia
...TTP traffic from DuckDB's internal HTTP client Yes PhysicalOperator Logs events emitted by physical operators during query execution Yes Metrics Logs profiling metrics collected during query execution Yes The structured log types expose the following sche... - https://man.mtool.work/duckdb/2.0/operations_manual/logging/overview.html
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