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- Bitstring Functions 14728
- This section describes functions and operators for examining and manipulating BITSTRING values. Bitstrings must be of equal length when performing the bitwise operands AND, OR and XOR. When bit shifting, the original length of the string is
...ions These aggregate functions are available for BIT type. Name Description bit_and(arg) Returns the bitwise AND operation performed on all bitstrings in a given expression. bit_or(arg) Returns the bitwise OR operation performed on all bitstrings in a giv...en expression. bit_xor(arg) Returns the bitwise XOR operation performed on all bitstrings in a given expression. bitstring_agg(arg) Returns a bitstring with bits set for each distinct position d...ange [ min , max ] or an Out of Range Error will be thrown. bit_and(arg) | Description | Returns the bitwise AND operation performed on all bitstrings in a given expression. | | Example | bit_and(A) | bit_or(arg) | Description | Returns the bitwise OR ope... - https://man.mtool.work/duckdb/2.0/sql/functions/bitstring.html
- Join Operations 10491
- 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
...way, DuckDB builds a left-deep join tree following the order of JOIN clauses. SELECT ... FROM ... JOIN ... -- this join is performed first JOIN ...; -- this join is performed second Once the query in question has been executed, turn back the optimizers wi... - https://man.mtool.work/duckdb/2.0/guides/performance/join_operations.html
- Replacement Scans 10308
- The replacement scan API can be used to register a callback that is called when a table is read that does not exist in the catalog. For example, when a query such as SELECT * FROM my_table is executed and my_table does not exist, the replac
...n_name Sets the replacement function name. If this function is called in the replacement callback, the replacement scan is performed. If it is not called, the replacement callback is not performed. Syntax void duckdb_replacement_scan_set_function_name ( d... - https://man.mtool.work/duckdb/2.0/clients/c/replacement_scans.html
- Azure Extension 9541
- The azure extension lets DuckDB read and write files in Azure Blob Storage and Azure Data Lake Storage (ADLS) Gen2. Installing and Loading The azure extension will be transparently autoloaded on first use from the official extension reposit
...hile the Blob endpoint lists every file under the prefix and filters afterwards. The following example shows how a glob is performed through each endpoint. Using the following filesystem: root ├── l_receiptmonth=1997-10 │ ├── l_shipmode=AIR │ │ └── data_0...pmode=AIR │ └── data_0.csv ├── l_shipmode=SHIP │ └── data_0.csv └── l_shipmode=TRUCK └── data_0.csv The following query is performed through the Blob endpoint: SELECT count(*) FROM 'az://root/l_receiptmonth=1997-*/l_shipmode=SHIP/*.csv'; It will perform t...1997-11/l_shipmode=SHIP/data_0.csv root/l_receiptmonth=1997-12/l_shipmode=SHIP/data_0.csv Meanwhile, the same query can be performed through the datalake endpoint as follows: SELECT count(*) FROM 'abfss://root/l_receiptmonth=1997-*/l_shipmode=SHIP/*.csv';... - https://man.mtool.work/duckdb/2.0/core_extensions/azure.html
- PostgreSQL Extension Functions 9541
- postgres_clear_cache postgres_configure_pool postgres_execute postgres_hstore_get postgres_hstore_to_json postgres_query read_postgres_binary postgres_clear_cache postgres_clear_cache() -> TABLE Clears cached schema entries (like table name
...no connection was available at the time - so no connection was provided by the pool; note that when the parallel scans are performed by the Postgres extension - worker threads always use the try acquire mode; when SET threads = ⟨number_higher_then_pool_si...se sql_query ( VARCHAR ): query that is passed to PostgreSQL for execution; no transformation or analysis of this query is performed by DuckDB Optional named parameters: use_transaction ( BOOLEAN , default: TRUE ): whether to start a PostgreSQL transactio...se sql_query ( VARCHAR ): query that is passed to PostgreSQL for execution; no transformation or analysis of this query is performed by DuckDB Optional named parameters: use_transaction ( BOOLEAN , default: TRUE ): whether to start a PostgreSQL transactio... - https://man.mtool.work/duckdb/2.0/core_extensions/postgres/functions.html
- Friendly CLI 8573
- Along with our Friendly SQL , we provide friendly CLI features. Dark/Light Mode The CLI automatically detects whether the terminal is using a dark or light background and adjusts syntax highlighting colors accordingly. The mode can also be
...┘ FROM _; ┌───────┐ │ x │ │ int32 │ ├───────┤ │ 42 │ └───────┘ If the last query did not return a result (e.g., because it performed an update operation), the CLI throws an error: Binder Error: Failed to query last result "_": no result available... - https://man.mtool.work/duckdb/2.0/clients/cli/friendly_cli.html
- Typecasting 8573
- Typecasting is an operation that converts a value in one particular data type to the closest corresponding value in another data type. Like other SQL engines, DuckDB supports both implicit and explicit typecasting. Explicit Casting Explicit
...typecasting is performed by using a CAST expression. For example, CAST(col AS VARCHAR) or col::VARCHAR explicitly cast the column col to VARCHAR ....ly selected parent type. For example, list_value(1::INT64, 1::UINT64) creates a list of type INT128[] . The implicit casts performed in this situation are sometimes more lenient than regular implicit casts. For example, a BOOL value may be cast to INT (wi... - https://man.mtool.work/duckdb/2.0/sql/data_types/typecasting.html
- CSV Auto Detection 8373
- When using read_csv , the system tries to automatically infer how to read the CSV file using the CSV sniffer . This step is necessary because CSV files are not self-describing and come in many different dialects. The auto-detection works ro
...ans the entire file is read for sampling: SELECT * FROM read_csv('my_csv_file.csv', sample_size = -1); The way sampling is performed depends on the type of file. If we are reading from a regular file on disk, we will jump into the file and try to sample f...detecting the dialect, the system will attempt to figure out the types of each of the columns. Note that this step is only performed if we are calling read_csv . In case of the COPY statement the types of the table that we are copying into will be used in... - https://man.mtool.work/duckdb/2.0/data/csv/auto_detection.html
- Casting 8190
- Casting refers to the operation of converting a value in a particular data type to the corresponding value in another data type. Casting can occur either implicitly or explicitly. The syntax described here performs an explicit cast. More in
..., it is not possible to convert an INTEGER to a DATE . Casts may also throw errors when the cast could not be successfully performed. For example, trying to cast the string 'hello' to an INTEGER will result in an error being thrown. SELECT CAST('hello' AS... - https://man.mtool.work/duckdb/2.0/sql/expressions/cast.html
- Comparisons 8190
- Comparison Operators The table below shows the standard comparison operators. Whenever either of the input arguments is NULL , the output of the comparison is NULL . Operator Description Example Result < less than 2 < 3 true > greater than
...bination Casting . These casts were introduced to make interactive querying more convenient and are in line with the casts performed by several programming languages but are often not compatible with PostgreSQL's behavior. For example, the following expre... - https://man.mtool.work/duckdb/2.0/sql/expressions/comparison_operators.html
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