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- Relational API – DuckDB 14011
- This page is for DuckDB 1.3, which is outdated. Switch to the current version . Search Shortcut cmd + k | ctrl + k Installation Documentation Getting Started Connect Overview Concurrency Data Import Overview Data Sources CSV Files Overview
...chain queries. The methods are lazy evaluated . Name Description aggregate Compute the aggregate aggr_expr by the optional groups group_expr on the relation apply Compute the function of a single column or a list of columns by the optional groups on th...group_expr : str = '' ) -> duckdb . duckdb . DuckDBPyRelation Description Compute the aggregate aggr_expr by the optional groups group_expr on the relation Parameters aggr_expr : str, list[Expression] The list of columns and aggregation functions. gro...uckdb . duckdb . DuckDBPyRelation Description Compute the function of a single column or a list of columns by the optional groups on the relation Parameters function_name : str Name of the function to apply over the relation. function_aggr : str The li... - https://man.mtool.work/duckdb/1.3/clients/python/relational_api.html
- Python Client API – DuckDB 11776
- This page is for DuckDB 1.3, which is outdated. Switch to the current version . Search Shortcut cmd + k | ctrl + k Installation Documentation Getting Started Connect Overview Concurrency Data Import Overview Data Sources CSV Files Overview
...expr : object , group_expr : str = '' ) → duckdb.duckdb.DuckDBPyRelation ¶ Compute the aggregate aggr_expr by the optional groups group_expr on the relation Detailed examples can be found at Relational API page . alias ¶ Get the name of the current ali...Detailed examples can be found at Relational API page . any_value ( self : duckdb.duckdb.DuckDBPyRelation , column : str , groups : str = '' , window_spec : str = '' , projected_columns : str = '' ) → duckdb.duckdb.DuckDBPyRelation ¶ Returns the first...str = '' ) → duckdb.duckdb.DuckDBPyRelation ¶ Compute the function of a single column or a list of columns by the optional groups on the relation Detailed examples can be found at Relational API page . arg_max ( self : duckdb.duckdb.DuckDBPyRelation ,... - https://man.mtool.work/duckdb/1.3/clients/python/reference/
- Parquet Tips – DuckDB 11326
- This page is for DuckDB 1.3, which is outdated. Switch to the current version . Search Shortcut cmd + k | ctrl + k Installation Documentation Getting Started Connect Overview Concurrency Data Import Overview Data Sources CSV Files Overview
...column chunk for each column in the dataset. Compression algorithms are only applied per row group, so the larger the row group size, the more opportunities to compress the data. DuckDB can read Parquet row groups in parallel even within the same file...and uses predicate pushdown to only scan the row groups whose metadata ranges match the WHERE clause of the query. However there is some overhead associated with reading the meta...data in each group. A good approach would be to ensure that within each file, the total number of row groups is at least as large as the number of CPU threads used to query that file. More row groups beyond the thread count would i... - https://man.mtool.work/duckdb/1.3/data/parquet/tips.html
- File Formats – DuckDB 8924
- This page is for DuckDB 1.3, which is outdated. Switch to the current version . Search Shortcut cmd + k | ctrl + k Installation Documentation Getting Started Connect Overview Concurrency Data Import Overview Data Sources CSV Files Overview
...un many queries on the same dataset, load the Parquet files into the database first. The compression algorithm and the row group sizes in the Parquet files have a large effect on performance: study these using the parquet_metadata function . The Effect...of Row Group Sizes DuckDB works best on Parquet files with row groups of 100K-1M rows each. The reason for this is that DuckDB can only...parallelize over row groups – so if a Parquet file has a single giant row group it can only be processed by a single thread. You can use the parquet_m... - https://man.mtool.work/duckdb/1.3/guides/performance/file_formats.html
- Regular Expressions – DuckDB 8873
- This page is for DuckDB 1.3, which is outdated. Switch to the current version . Search Shortcut cmd + k | ctrl + k Installation Documentation Getting Started Connect Overview Concurrency Data Import Overview Data Sources CSV Files Overview
...tion regexp_extract(string, pattern[, group = 0][, options]) If string contains the regexp pattern , returns the capturing group specified by optional parameter group ; otherwise, returns the empty string. The group must be a constant value. If no grou...e set. regexp_extract(string, pattern, name_list[, options]) If string contains the regexp pattern , returns the capturing groups as a struct with corresponding names from name_list ; otherwise, returns a struct with the same keys and empty strings as...extract(string, pattern[, group = 0][, options]) Description If string contains the regexp pattern , returns the capturing group specified by optional parameter group ; otherwise, returns the empty string. The group must be a constant value. If no grou... - https://man.mtool.work/duckdb/1.3/sql/functions/regular_expressions.html
- Window Functions – DuckDB 8390
- This page is for DuckDB 1.3, which is outdated. Switch to the current version . Search Shortcut cmd + k | ctrl + k Installation Documentation Getting Started Connect Overview Concurrency Data Import Overview Data Sources CSV Files Overview
...with current row) / total partition rows. dense_rank() The rank of the current row without gaps; this function counts peer groups. first_value(expr[ ORDER BY ordering][ IGNORE NULLS]) Returns expr evaluated at the row that is the first row (with a non-...pe DOUBLE Example cume_dist() dense_rank() Description The rank of the current row without gaps; this function counts peer groups. Return type BIGINT Example dense_rank() Aliases rank_dense() first_value(expr[ ORDER BY ordering][ IGNORE NULLS]) Descrip...pecified as a number of rows , as a range of values using the partition's ordering value and a distance, or as a number of groups (sets of rows with the same sort value). The full syntax is shown in the diagram at the top of the page, and this diagram... - https://man.mtool.work/duckdb/1.3/sql/functions/window_functions.html
- Tuning Workloads – DuckDB 8273
- This page is for DuckDB 1.3, which is outdated. Switch to the current version . Search Shortcut cmd + k | ctrl + k Installation Documentation Getting Started Connect Overview Concurrency Data Import Overview Data Sources CSV Files Overview
...do not contain ORDER BY clauses, potentially reducing memory usage. Parallelism (Multi-Core Processing) The Effect of Row Groups on Parallelism DuckDB parallelizes the workload based on row groups , i.e., groups of rows that are stored together at the...orage level. A row group in DuckDB's database format consists of max. 122,880 rows. Parallelism starts at the level of row groups, therefore, for a query to run on k threads, it needs to scan at least k * 122,880 rows. Too Many Threads Note that in cer...ademark Use Blog In this article The preserve_insertion_order Option Parallelism (Multi-Core Processing) The Effect of Row Groups on Parallelism Too Many Threads Larger-than-Memory Workloads (Out-of-Core Processing) Spilling to Disk Blocking Operators... - https://man.mtool.work/duckdb/1.3/guides/performance/how_to_tune_workloads.html
- Storage Versions and Format – DuckDB 8273
- This page is for DuckDB 1.3, which is outdated. Switch to the current version . Search Shortcut cmd + k | ctrl + k Installation Documentation Getting Started Connect Overview Concurrency Data Import Overview Data Sources CSV Files Overview
...tabase file will require 25 GB of disk space, while loading 100 GB of Parquet files will require 120 GB of disk space. Row Groups DuckDB's storage format stores the data in row groups, i.e., horizontal partitions of the data. This concept is equivalent...to Parquet's row groups . Several features in DuckDB, including parallelism and compression are based on row groups. Troubleshooting Error Message...Converting between Storage Versions Storage Header Storage Version Table Compression Compression Algorithms Disk Usage Row Groups Troubleshooting Error Message When Opening an Incompatible Database File... - https://man.mtool.work/duckdb/1.3/internals/storage.html
- Querying Parquet Metadata – DuckDB 8223
- This page is for DuckDB 1.3, which is outdated. Switch to the current version . Search Shortcut cmd + k | ctrl + k Installation Documentation Getting Started Connect Overview Concurrency Data Import Overview Data Sources CSV Files Overview
...of the columns returned by parquet_file_metadata . Field Type file_name VARCHAR created_by VARCHAR num_rows BIGINT num_row_groups BIGINT format_version BIGINT encryption_algorithm VARCHAR footer_signing_key_metadata VARCHAR Parquet Key-Value Metadata T...etadata . Field Type file_name VARCHAR key BLOB value BLOB Bloom Filters DuckDB supports Bloom filters for pruning the row groups that need to be read to answer highly selective queries. Currently, Bloom filters are supported for the following types: I...ng point types: FLOAT , DOUBLE VARCHAR BLOB The parquet_bloom_probe(filename, column_name, value) function shows which row groups can excluded when filtering for a given value of a given column using the Bloom filter. For example: FROM parquet_bloom_pr... - https://man.mtool.work/duckdb/1.3/data/parquet/metadata.html
- Indexing – DuckDB 8106
- This page is for DuckDB 1.3, which is outdated. Switch to the current version . Search Shortcut cmd + k | ctrl + k Installation Documentation Getting Started Connect Overview Concurrency Data Import Overview Data Sources CSV Files Overview
...a column could contain a random number on every row in the worst case. Then, DuckDB will likely be unable to skip any row groups. If you query specific columns with selective filters, it is best to pre-order data by those columns when inserting it. Ev...mns queried using selective filters. In a scenario where a table contains out-of-order UUID s, DuckDB has to scan many row groups to find a specific UUID value. An ordered INTEGER column allows skipping all row groups except those containing the value....an scans memory columns these Indexes performance queries ordered selective filters order using allows table zonemaps also groups constraints indexed single 関連するページ Indexes Tuning Workloads CREATE INDEX Statement Vector Similarity Search Extensi... - https://man.mtool.work/duckdb/1.3/guides/performance/indexing.html
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