Results of 1 - 10 of about 13 for optimization (0.002 sec.)
- Join Operations 13003
- How to Force a Join Order DuckDB has a cost-based query optimizer, which uses statistics in the base tables (stored in a DuckDB database or Parquet files) to estimate the cardinality of operations. Turn off the Join Order Optimizer To turn
...der_threshold = 16; Raising the threshold can lead to better join orders for queries with many joins at the cost of longer optimization times. Lowering it reduces optimization time for large joins. Even below the threshold, the optimizer falls back to the ap... - https://man.mtool.work/duckdb/2.0/guides/performance/join_operations.html
- ANALYZE Statement 12035
- The ANALYZE statement recomputes the statistics on DuckDB's tables. Usage The statistics recomputed by the ANALYZE statement are only used for join order optimization . It is therefore recommended to recompute these statistics for improved
... - https://man.mtool.work/duckdb/2.0/sql/statements/analyze.html
- DuckDB Environment 9818
- DuckDB provides a number of functions and PRAGMA options to retrieve information on the running DuckDB instance and its environment. Version The version() function returns the version number of DuckDB. SELECT version() AS version; version v
...indexes() : secondary indexes duckdb_keywords() : DuckDB's keywords and reserved words duckdb_optimizers() : the available optimization rules in the DuckDB instance duckdb_schemas() : schemas duckdb_sequences() : sequences duckdb_settings() : settings duckdb... - https://man.mtool.work/duckdb/2.0/guides/meta/duckdb_environment.html
- Pragmas 8868
- 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
...of the available metrics . Disable Profiling To disable profiling: PRAGMA disable_profiling; PRAGMA disable_profile; Query Optimization Optimizer To disable the query optimizer: PRAGMA disable_optimizer; To enable the query optimizer: PRAGMA enable_optimizer...; Selectively Disabling Optimizers The disabled_optimizers option allows selectively disabling optimization steps. For example, to disable filter_pushdown and statistics_propagation , run: SET disabled_optimizers = 'filter_pushdow...n,statistics_propagation'; The available optimizations can be queried using the duckdb_optimizers() table function . To re-enable the optimizers, run: SET disabled_optimizers =... - https://man.mtool.work/duckdb/2.0/configuration/pragmas.html
- Execution Format 8551
- 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 exec
...enerally emitted for row identifiers. Unified Vector Format These properties of the different vector formats are great for optimization purposes, for example you can imagine the scenario where all the parameters to a function are constant, we can just comput... - https://man.mtool.work/duckdb/2.0/internals/vector.html
- File Formats 8234
- Handling Parquet Files DuckDB has advanced support for Parquet files, which includes directly querying Parquet files . When deciding on whether to query these files directly or to first load them to the database, you need to consider severa
...se a columnar storage format and contain basic statistics such as zonemaps . Thanks to these features, DuckDB can leverage optimizations such as projection and filter pushdown on Parquet files. Therefore, workloads that combine projection, filtering, and agg...reader runs the CSV sniffer on all files. For many small files, this may cause an unnecessarily high overhead. A potential optimization to speed this up is to turn the sniffer off. Assuming that all files have the same CSV dialect and column names/types, get... - https://man.mtool.work/duckdb/2.0/guides/performance/file_formats.html
- Enum Data Type 8234
- Name Description ENUM Dictionary representing all possible string values of a column The enum type represents a dictionary data structure with all possible unique values of a column. For example, a column storing the days of the week can be
...`WHERE current_mood::VARCHAR = name` -- No rows returned When comparing against a constant string, DuckDB will perform an optimization and try_cast(⟨constant string⟩, enum_type) so that physically we are doing an integer comparison instead of a string compa... - https://man.mtool.work/duckdb/2.0/sql/data_types/enum.html
- DuckDB_% Metadata Functions 8234
- DuckDB offers a collection of table functions that provide metadata about the current database. These functions reside in the main schema and their names are prefixed with duckdb_ . The resultset returned by a duckdb_ table function may be
...es The disk storage used (in bytes). BIGINT duckdb_optimizers The duckdb_optimizers() function provides metadata about the optimization rules (e.g., expression_rewriter , filter_pushdown ) available in the DuckDB instance. These can be selectively turned off...using PRAGMA disabled_optimizers . Column Description Type name The name of the optimization rule. VARCHAR duckdb_prepared_statements The duckdb_prepared_statements() function provides metadata about the prepared st... - https://man.mtool.work/duckdb/2.0/sql/meta/duckdb_table_functions.html
- Reading Faulty CSV Files 7900
- CSV files can come in all shapes and forms, with some presenting many errors that make the process of cleanly reading them inherently difficult. To help users read these files, DuckDB supports detailed error messages, the ability to skip fa
...ore_errors = true ); Outputs: name age Pedro 31 One should note that the CSV Parser is affected by the projection pushdown optimization. Hence, if we were to select only the name column, both rows would be considered valid, as the casting error on the age wo... - https://man.mtool.work/duckdb/2.0/data/csv/reading_faulty_csv_files.html
- Migrating to DuckDB 2.0 7900
- DuckDB 2.0.0 is packed with new features and performance improvements, including query optimization and asynchronous I/O. It also ships a small set of breaking changes, most notably a new default storage format, which DuckDB versions before
... - https://man.mtool.work/duckdb/2.0/operations_manual/migration.html
DuckDB 2.0 Documentation / man.mtool.work