Results of 1 - 10 of about 30 for Filters (0.001 sec.)
- EXPLAIN ANALYZE: Profile Queries 12119
- 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
...n.students │ │ Type: Sequential Scan │ │ Type: Sequential Scan │ │ Projections: sid │ │ Projections: sid, name │ │ Dynamic Filters: │ │ Filters: name >= 'Ma' │ │ optional: (sid IN (1, 3)) AND optional: sid IN PRF(sid) │ │ Row Groups Scanned: 1 / 1 │ │ R...er of rows it produced and the time spent in it. Scan operators also show the number of row groups scanned and any dynamic filters that were pushed into them at runtime, e.g., by the hash join. See Also For more information, see the ”Profiling” page .... - https://man.mtool.work/duckdb/2.0/guides/meta/explain_analyze.html
- Indexing 11924
- 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
...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. Even an imperfect ordering will still be helpful. The be...exploit ordering is to use the INTEGER type with automatic increments rather than UUID for columns 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 valu...formance of some queries. DuckDB will try to use an index scan for equality and IN(...) conditions. It also pushes dynamic filters, e.g., from hash joins, into the scan, allowing dynamic index scans on these filters. Indexes are only eligible for index... - https://man.mtool.work/duckdb/2.0/guides/performance/indexing.html
- Overview of DuckDB Internals 11291
- 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
...query optimizers are run: Expression Rewriter : Simplifies expressions, performs constant folding Filter Pushdown : Pushes filters down into the query plan and duplicates filters over equivalency sets. Also prunes subtrees that are guaranteed to be empt...y (because of filters that statically evaluate to false). Join Order Optimizer : Reorders joins using dynamic programming. Specifically, the DPh... - https://man.mtool.work/duckdb/2.0/internals/overview.html
- SQL on Apache Arrow 10462
- DuckDB can query multiple different types of Apache Arrow objects. DuckDB pushes the filters of a query that it can translate, such as comparisons, into the scan of an Arrow dataset. Arrow tables, record batches, scanners and RecordBatchRea
...ul to point towards directories of Parquet files to analyze large datasets. DuckDB will push column selections and the row filters it can translate down into the dataset scan operation so that only the necessary data is pulled into memory. import duckdb...ataset and select specific columns or apply row-wise filtering. This is similar to how DuckDB pushes column selections and filters down into an Arrow Dataset, but using Arrow compute operations instead. Arrow can use asynchronous IO to quickly access fi... - https://man.mtool.work/duckdb/2.0/guides/python/sql_on_arrow.html
- Querying Parquet Metadata 10251
- Parquet Metadata The parquet_metadata function can be used to query the metadata contained within a Parquet file, which reveals various internal details of the Parquet file such as the statistics of the different columns. This can be useful
...quet_kv_metadata STRUCT(...)[] Each struct array contains the same columns as the corresponding standalone function. Bloom Filters DuckDB supports Bloom filters for pruning the row groups that need to be read to answer highly selective queries. Currentl...y, Bloom filters are supported for the following types: Integer types: TINYINT , UTINYINT , SMALLINT , USMALLINT , INTEGER , UINTEGER , BIG... - https://man.mtool.work/duckdb/2.0/data/parquet/metadata.html
- Tuning Workloads 10056
- DuckDB aims to perform well out of the box, so most workloads do not require any tuning. When tuning is worthwhile, there is no single configuration or magic number that is optimal for every workload: the right settings depend on what you a
.... Instead, only select columns that are actually used. DuckDB will try to only download the data it actually needs. Apply filters on remote Parquet files when possible. DuckDB can use these filters to reduce the amount of data that is scanned. Either s...ort or partition data by columns that are regularly used for filters: this increases the effectiveness of the filters in reducing IO. To inspect how much remote data is transferred for a quer... - https://man.mtool.work/duckdb/2.0/guides/performance/how_to_tune_workloads.html
- Querying Parquet Files 9227
- To run a query directly on a Parquet file, use the read_parquet function in the FROM clause of a query. SELECT * FROM read_parquet('input.parquet'); The Parquet file will be processed in parallel. Filters will be automatically pushed down i
... - https://man.mtool.work/duckdb/2.0/guides/file_formats/query_parquet.html
- WHERE Clause 8805
- The WHERE clause specifies any filters to apply to the data. This allows you to select only a subset of the data in which you are interested. Logically the WHERE clause is applied immediately after the FROM clause. Examples Select all rows
... - https://man.mtool.work/duckdb/2.0/sql/query_syntax/where.html
- FILTER Clause 8399
- The FILTER clause may optionally follow an aggregate function in a SELECT statement. This will filter the rows of data that are fed into the aggregate function in the same way that a WHERE clause filters rows, but localized to the specific
...There are multiple types of situations where this is useful, including when evaluating multiple aggregates with different filters, and when creating a pivoted view of a dataset. FILTER provides a cleaner syntax for pivoting data when compared with the... - https://man.mtool.work/duckdb/2.0/sql/query_syntax/filter.html
- Unity Catalog Extension 7976
- The unity_catalog extension attaches a Unity Catalog catalog, on Databricks or Unity Catalog OSS, as a DuckDB database. You can list, read, insert into and create its Delta Lake tables. It uses the delta extension to access the tables. For
...iles that a query scans. Unity Catalog OSS does not offer this API. With USE_IRC_SCAN_PLAN true , DuckDB sends each scan's filters to the server and reads only the files that it returns, with their delete files. DuckDB still applies the filters itself:... - https://man.mtool.work/duckdb/2.0/core_extensions/unity_catalog.html
DuckDB 2.0 Documentation / man.mtool.work