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80 lines
3.8 KiB
Markdown
80 lines
3.8 KiB
Markdown
---
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slug: /en/sql-reference/table-functions/url
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sidebar_position: 200
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sidebar_label: url
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---
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# url
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`url` function creates a table from the `URL` with given `format` and `structure`.
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`url` function may be used in `SELECT` and `INSERT` queries on data in [URL](../../engines/table-engines/special/url.md) tables.
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**Syntax**
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``` sql
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url(URL [,format] [,structure] [,headers])
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```
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**Parameters**
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- `URL` — HTTP or HTTPS server address, which can accept `GET` or `POST` requests (for `SELECT` or `INSERT` queries correspondingly). Type: [String](../../sql-reference/data-types/string.md).
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- `format` — [Format](../../interfaces/formats.md#formats) of the data. Type: [String](../../sql-reference/data-types/string.md).
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- `structure` — Table structure in `'UserID UInt64, Name String'` format. Determines column names and types. Type: [String](../../sql-reference/data-types/string.md).
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- `headers` - Headers in `'headers('key1'='value1', 'key2'='value2')'` format. You can set headers for HTTP call.
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**Returned value**
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A table with the specified format and structure and with data from the defined `URL`.
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**Examples**
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Getting the first 3 lines of a table that contains columns of `String` and [UInt32](../../sql-reference/data-types/int-uint.md) type from HTTP-server which answers in [CSV](../../interfaces/formats.md#csv) format.
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``` sql
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SELECT * FROM url('http://127.0.0.1:12345/', CSV, 'column1 String, column2 UInt32', headers('Accept'='text/csv; charset=utf-8')) LIMIT 3;
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```
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Inserting data from a `URL` into a table:
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``` sql
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CREATE TABLE test_table (column1 String, column2 UInt32) ENGINE=Memory;
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INSERT INTO FUNCTION url('http://127.0.0.1:8123/?query=INSERT+INTO+test_table+FORMAT+CSV', 'CSV', 'column1 String, column2 UInt32') VALUES ('http interface', 42);
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SELECT * FROM test_table;
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```
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## Globs in URL
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Patterns in curly brackets `{ }` are used to generate a set of shards or to specify failover addresses. Supported pattern types and examples see in the description of the [remote](remote.md#globs-in-addresses) function.
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Character `|` inside patterns is used to specify failover addresses. They are iterated in the same order as listed in the pattern. The number of generated addresses is limited by [glob_expansion_max_elements](../../operations/settings/settings.md#glob_expansion_max_elements) setting.
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## Virtual Columns
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- `_path` — Path to the `URL`. Type: `LowCardinalty(String)`.
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- `_file` — Resource name of the `URL`. Type: `LowCardinalty(String)`.
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- `_size` — Size of the resource in bytes. Type: `Nullable(UInt64)`. If the size is unknown, the value is `NULL`.
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- `_time` — Last modified time of the file. Type: `Nullable(DateTime)`. If the time is unknown, the value is `NULL`.
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- `_headers` - HTTP response headers. Type: `Map(LowCardinality(String), LowCardinality(String))`.
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## Hive-style partitioning {#hive-style-partitioning}
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When setting `use_hive_partitioning` is set to 1, ClickHouse will detect Hive-style partitioning in the path (`/name=value/`) and will allow to use partition columns as virtual columns in the query. These virtual columns will have the same names as in the partitioned path, but starting with `_`.
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**Example**
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Use virtual column, created with Hive-style partitioning
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``` sql
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SET use_hive_partitioning = 1;
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SELECT * from url('http://data/path/date=*/country=*/code=*/*.parquet') where _date > '2020-01-01' and _country = 'Netherlands' and _code = 42;
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```
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## Storage Settings {#storage-settings}
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- [engine_url_skip_empty_files](/docs/en/operations/settings/settings.md#engine_url_skip_empty_files) - allows to skip empty files while reading. Disabled by default.
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- [enable_url_encoding](/docs/en/operations/settings/settings.md#enable_url_encoding) - allows to enable/disable decoding/encoding path in uri. Enabled by default.
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**See Also**
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- [Virtual columns](/docs/en/engines/table-engines/index.md#table_engines-virtual_columns)
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