Results of 1 - 10 of about 19 for cardinality (0.002 sec.)
- Table Functions 13933
- The table function API can be used to define a table function that can then be called from within DuckDB in the FROM clause of a query. API Reference Overview duckdb_table_function duckdb_create_table_function (); void duckdb_destroy_table_
...b_bind_set_bind_data ( duckdb_bind_info info , void * bind_data , duckdb_delete_callback_t destroy ); void duckdb_bind_set_cardinality ( duckdb_bind_info info , idx_t cardinality , bool is_exact ); void duckdb_bind_set_error ( duckdb_bind_info info , const...able function. bind_data : The bind data object. destroy : The callback to destroy the bind data (if any). duckdb_bind_set_cardinality Sets the cardinality estimate for the table function, used for optimization. Syntax void duckdb_bind_set_cardinality ( duc...kdb_bind_info info , idx_t cardinality , bool is_exact ); Parameters info : The bind data object. is_exact : Whether or not the cardinality estimate is exact, or... - https://man.mtool.work/duckdb/2.0/clients/c/table_functions.html
- Write User Defined Functions 11013
- Overview The Go client can register user-defined functions written in Go: scalar functions that map input rows to a single output value, and table functions that produce a set of rows. It can also register a replacement scan that rewrites a
...ing one duckdb.Row per call with duckdb.SetRowValue() and returning true while there are more rows, false to end the scan. Cardinality() returns an optional row-count estimate. Register the function with duckdb.RegisterTableUDF() . The following defines inc...scan } udf.currentRow++ err := duckdb.SetRowValue(row, 0, udf.currentRow) return true, err } func (udf *incrementTableUDF) Cardinality() *duckdb.CardinalityInfo { return &duckdb.CardinalityInfo{Cardinality: uint(udf.tableSize), Exact: true} } func main() {... - https://man.mtool.work/duckdb/2.0/clients/go/functions.html
- Map Functions 10757
- Name Description cardinality(map) Return the size of the map (or the number of entries in the map). element_at(map, key) Return the value for a given key as a list, or an empty list if the key is not contained in the map. The type of the ke
...sent. An optional third argument, switch(key, map, default) , returns default instead of NULL when the key is not present. cardinality(map) | Description | Return the size of the map (or the number of entries in the map). | | Example | cardinality(map([4, 2... - https://man.mtool.work/duckdb/2.0/sql/functions/map.html
- Delta Extension 9425
- The delta extension adds support for the Delta Lake open-source storage format . It is built using the Delta Kernel . The extension reads Delta tables, local and remote, and writes them: it can create tables and append to them. For implemen
...ly' ); Inspecting Scanned Files delta_list_files returns the data files a scan would read for a table, together with their cardinality, partition values, and whether they carry deletion vectors. This is useful for understanding the effect of data skipping :...SELECT * FROM delta_list_files('file:///⟨path⟩'); Column Type Description data_file VARCHAR Path to the Parquet data file. cardinality UBIGINT Number of rows in the file. partitions MAP(VARCHAR, VARCHAR) Partition column values for the file. have_deletes BO...te_count column with the number of rows each file's deletion vector removes, pass delete_count => true : SELECT data_file, cardinality, delete_count FROM delta_list_files('file:///⟨path⟩', version => 3, delete_count => true); Reading Domain Metadata Since v... - https://man.mtool.work/duckdb/2.0/core_extensions/delta.html
- Metrics 8896
- DuckDB provides a set of metrics that can be used to monitor the performance and health of the database. Metrics are named ⟨group⟩.⟨metric⟩ , e.g., query.total_time or operator.timing . The set of collected metrics is controlled with the tr
...es": 0, "timing": 5.458e-06, "type": "RESULT_COLLECTOR", "children": [ { "extra_info": { "Projections": "name", "Estimated Cardinality": "1" }, "intermediate_rows": 2, "intermediate_size_bytes": 40, "timing": 8.3e-08, "type": "PROJECTION", "children": [ { "...extra_info": { "Join Type": "INNER", "Conditions": "sid = sid", "Estimated Cardinality": "1" }, "intermediate_rows": 2, "intermediate_size_bytes": 48, "timing": 4.4209e-05, "type": "HASH_JOIN", "children": [ .... - https://man.mtool.work/duckdb/2.0/dev/metrics.html
- EXPLAIN: Inspect Query Plans 8623
- EXPLAIN SELECT * FROM tbl; The EXPLAIN statement displays the physical plan, i.e., the query plan that will get executed, and is enabled by prepending the query with EXPLAIN . The physical plan is a tree of operators that are executed in a
...│ ╰─────────────────────────────╯ Note that the query is not actually executed – therefore, we can only see the estimated cardinality for each operator (shown with a ~ prefix, e.g., ~3 rows ), which is calculated by using the statistics of the base tables... - https://man.mtool.work/duckdb/2.0/guides/meta/explain.html
- EXPLAIN ANALYZE: Profile Queries 8623
- Prepending a query with EXPLAIN ANALYZE both pretty-prints the query plan, and executes it, providing run-time performance numbers and the actual cardinality (number of rows produced) for every operator. EXPLAIN ANALYZE SELECT * FROM tbl; N
... - https://man.mtool.work/duckdb/2.0/guides/meta/explain_analyze.html
- Join Operations 8623
- 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
... - https://man.mtool.work/duckdb/2.0/guides/performance/join_operations.html
- Data Chunks 7837
- Data chunks represent a horizontal slice of a table. They hold a number of vectors , that can each hold up to the VECTOR_SIZE rows. The vector size can be obtained through the duckdb_vector_size function and is configurable, but is usually
...hunk : The data chunk to destroy. duckdb_data_chunk_reset Resets a data chunk, clearing the validity masks and setting the cardinality of the data chunk to 0. After calling this method, you must call duckdb_vector_get_validity and duckdb_vector_get_data to... - https://man.mtool.work/duckdb/2.0/clients/c/data_chunk.html
- Indexing 7837
- 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
...bl (col1, col2); CREATE INDEX idx_expr ON tbl (col1 + 1); The default threshold for index scans is MAX(2048, 0.001 * table_cardinality) . You can configure this threshold via index_scan_percentage and index_scan_max_count , or disable them by setting these... - https://man.mtool.work/duckdb/2.0/guides/performance/indexing.html
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