Weijun-H commented on code in PR #7520: URL: https://github.com/apache/arrow-datafusion/pull/7520#discussion_r1320979617
########## docs/source/user-guide/sql/write_options.md: ########## @@ -0,0 +1,131 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# Write Options + +DataFusion supports customizing how data is written out to disk as a result of a `COPY` or `INSERT INTO` query. There are a few special options, file format (e.g. CSV or parquet) specific options, and parquet column specific options. Options can also in some cases be specified in multiple ways with a set order of precedence. + +## Specifying Options and Order of Precedence + +Write related options can be specified in the following ways: + +- Session level config defaults +- `CREATE EXTERNAL TABLE` options +- `COPY` option tuples + +For a list of supported session level config defaults see [Configuration Settings](https://arrow.apache.org/datafusion/user-guide/configs.html). These defaults apply to all write operations but have the lowest level of precedence. + +If inserting to an external table, table specific write options can be specified when the table is created: + +```sql +CREATE EXTERNAL TABLE +my_table(a bigint, b bigint) +STORED AS csv +COMPRESSION TYPE gzip +WITH HEADER ROW +DELIMETER ';' +LOCATION '/test/location/my_csv_table/' +OPTIONS( +CREATE_LOCAL_PATH 'true', +NULL_VALUE 'NAN' +); +``` + +When running `INSERT INTO my_table ...`, the above specified options will be respected (gzip compression, special delimiter, and header row included). Note that compression, header, and delimeter settings can also be specified within the `OPTIONS` tuple list. Dedicated syntax within the SQL statement always takes precedence over arbitrary option tuples, so if both are specified the `OPTIONS` setting will be ignored. CREATE_LOCAL_PATH is a special option that indicates if DataFusion should create local file paths when writing new files if they do not already exist. This option is useful if you wish to create an external table from scratch, using only DataFusion SQL statements. Finally, NULL_VALUE is a CSV format specific option that determines how null values should be encoded within the CSV file. + +Finally, options can be passed when running a `COPY` command. + +```sql +COPY source_table +TO 'test/table_with_options' +(format parquet, +single_file_output false, +compression snappy, +'compression::col1' 'zstd(5)', +) +``` + +In this example, we write the entirety of `source_table` out to a folder of parquet files. The option `single_file_output` set to false, indicates that the destination path should be interpreted as a folder to which the query will output multiple files. One parquet file will be written in parallel to the folder for each partition in the query. The next option `compression` set to `snappy` indicates that unless otherwise specified all columns should use the snappy compression codec. The option `compression::col1` sets an override, so that the column `col1` in the parquet file will use `ZSTD` compression codec with compression level `5`. In general, parquet option which support column specific settings can be specified with the syntax `OPTION::COLUMN.NESTED.PATH`. + +## Available Options + +### COPY Specific Options + +The following special options are specific to the `COPY` query. + +| Option | Description | Default Value | +| ------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------- | +| SINGLE_FILE_OUTPUT | If true, COPY query will write output to a single file. Otherwise, multiple files will be written to a directory in parallel. | true | +| FORMAT | Specifies the file format COPY query will write out. If single_file_output is false or format cannot be inferred from file extension, then FORMAT must be specified. | N/A | + +### CREATE EXTERNAL TABLE Specific Options + +The following special options are specific to creating an external table. + +| Option | Description | Default Value | +| ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------- | +| SINGLE_FILE | If true, indicates that this external table is backed by a single file. INSERT INTO queries will append to this file. | false | +| CREATE_LOCAL_PATH | If true, the folder or file backing this table will be created on the local file system if it does not already exist when running INSERT INTO queries. | false | +| INSERT_MODE | Determines if INSERT INTO queries should append to existing files or append new files to an existing directory. Valid values are append_to_file, append_new_files, and error. Note that "error" will block inserting data into this table. | CSV and JSON default to append_to_file. Parquet defaults to append_new_files | + +### JSON Format Specific Options + +The following options are available when writting JSON files. Note: if any unsupported option is specified, an error will be raised and the query will fail. Review Comment: ```suggestion The following options are available when writing JSON files. Note: If any unsupported option is specified, an error will be raised and the query will fail. ``` ########## docs/source/user-guide/sql/write_options.md: ########## @@ -0,0 +1,131 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# Write Options + +DataFusion supports customizing how data is written out to disk as a result of a `COPY` or `INSERT INTO` query. There are a few special options, file format (e.g. CSV or parquet) specific options, and parquet column specific options. Options can also in some cases be specified in multiple ways with a set order of precedence. + +## Specifying Options and Order of Precedence + +Write related options can be specified in the following ways: + +- Session level config defaults +- `CREATE EXTERNAL TABLE` options +- `COPY` option tuples + +For a list of supported session level config defaults see [Configuration Settings](https://arrow.apache.org/datafusion/user-guide/configs.html). These defaults apply to all write operations but have the lowest level of precedence. + +If inserting to an external table, table specific write options can be specified when the table is created: + +```sql +CREATE EXTERNAL TABLE +my_table(a bigint, b bigint) +STORED AS csv +COMPRESSION TYPE gzip +WITH HEADER ROW +DELIMETER ';' Review Comment: ```suggestion DELIMITER ';' ``` ########## docs/source/user-guide/sql/write_options.md: ########## @@ -0,0 +1,131 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# Write Options + +DataFusion supports customizing how data is written out to disk as a result of a `COPY` or `INSERT INTO` query. There are a few special options, file format (e.g. CSV or parquet) specific options, and parquet column specific options. Options can also in some cases be specified in multiple ways with a set order of precedence. + +## Specifying Options and Order of Precedence + +Write related options can be specified in the following ways: + +- Session level config defaults +- `CREATE EXTERNAL TABLE` options +- `COPY` option tuples + +For a list of supported session level config defaults see [Configuration Settings](https://arrow.apache.org/datafusion/user-guide/configs.html). These defaults apply to all write operations but have the lowest level of precedence. + +If inserting to an external table, table specific write options can be specified when the table is created: + +```sql +CREATE EXTERNAL TABLE +my_table(a bigint, b bigint) +STORED AS csv +COMPRESSION TYPE gzip +WITH HEADER ROW +DELIMETER ';' +LOCATION '/test/location/my_csv_table/' +OPTIONS( +CREATE_LOCAL_PATH 'true', +NULL_VALUE 'NAN' +); +``` + +When running `INSERT INTO my_table ...`, the above specified options will be respected (gzip compression, special delimiter, and header row included). Note that compression, header, and delimeter settings can also be specified within the `OPTIONS` tuple list. Dedicated syntax within the SQL statement always takes precedence over arbitrary option tuples, so if both are specified the `OPTIONS` setting will be ignored. CREATE_LOCAL_PATH is a special option that indicates if DataFusion should create local file paths when writing new files if they do not already exist. This option is useful if you wish to create an external table from scratch, using only DataFusion SQL statements. Finally, NULL_VALUE is a CSV format specific option that determines how null values should be encoded within the CSV file. + +Finally, options can be passed when running a `COPY` command. + +```sql +COPY source_table +TO 'test/table_with_options' +(format parquet, +single_file_output false, +compression snappy, +'compression::col1' 'zstd(5)', +) +``` + +In this example, we write the entirety of `source_table` out to a folder of parquet files. The option `single_file_output` set to false, indicates that the destination path should be interpreted as a folder to which the query will output multiple files. One parquet file will be written in parallel to the folder for each partition in the query. The next option `compression` set to `snappy` indicates that unless otherwise specified all columns should use the snappy compression codec. The option `compression::col1` sets an override, so that the column `col1` in the parquet file will use `ZSTD` compression codec with compression level `5`. In general, parquet option which support column specific settings can be specified with the syntax `OPTION::COLUMN.NESTED.PATH`. + +## Available Options + +### COPY Specific Options + +The following special options are specific to the `COPY` query. + +| Option | Description | Default Value | +| ------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------- | +| SINGLE_FILE_OUTPUT | If true, COPY query will write output to a single file. Otherwise, multiple files will be written to a directory in parallel. | true | +| FORMAT | Specifies the file format COPY query will write out. If single_file_output is false or format cannot be inferred from file extension, then FORMAT must be specified. | N/A | + +### CREATE EXTERNAL TABLE Specific Options + +The following special options are specific to creating an external table. + +| Option | Description | Default Value | +| ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------- | +| SINGLE_FILE | If true, indicates that this external table is backed by a single file. INSERT INTO queries will append to this file. | false | Review Comment: ```suggestion | SINGLE_FILE | If true, indicates that this external table is backed by a single file. INSERT INTO queries will be appended to this file. | false | ``` ########## docs/source/user-guide/sql/write_options.md: ########## @@ -0,0 +1,131 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# Write Options + +DataFusion supports customizing how data is written out to disk as a result of a `COPY` or `INSERT INTO` query. There are a few special options, file format (e.g. CSV or parquet) specific options, and parquet column specific options. Options can also in some cases be specified in multiple ways with a set order of precedence. + +## Specifying Options and Order of Precedence + +Write related options can be specified in the following ways: + +- Session level config defaults +- `CREATE EXTERNAL TABLE` options +- `COPY` option tuples + +For a list of supported session level config defaults see [Configuration Settings](https://arrow.apache.org/datafusion/user-guide/configs.html). These defaults apply to all write operations but have the lowest level of precedence. + +If inserting to an external table, table specific write options can be specified when the table is created: + +```sql +CREATE EXTERNAL TABLE +my_table(a bigint, b bigint) +STORED AS csv +COMPRESSION TYPE gzip +WITH HEADER ROW +DELIMETER ';' +LOCATION '/test/location/my_csv_table/' +OPTIONS( +CREATE_LOCAL_PATH 'true', +NULL_VALUE 'NAN' +); +``` + +When running `INSERT INTO my_table ...`, the above specified options will be respected (gzip compression, special delimiter, and header row included). Note that compression, header, and delimeter settings can also be specified within the `OPTIONS` tuple list. Dedicated syntax within the SQL statement always takes precedence over arbitrary option tuples, so if both are specified the `OPTIONS` setting will be ignored. CREATE_LOCAL_PATH is a special option that indicates if DataFusion should create local file paths when writing new files if they do not already exist. This option is useful if you wish to create an external table from scratch, using only DataFusion SQL statements. Finally, NULL_VALUE is a CSV format specific option that determines how null values should be encoded within the CSV file. + +Finally, options can be passed when running a `COPY` command. + +```sql +COPY source_table +TO 'test/table_with_options' +(format parquet, +single_file_output false, +compression snappy, +'compression::col1' 'zstd(5)', +) +``` + +In this example, we write the entirety of `source_table` out to a folder of parquet files. The option `single_file_output` set to false, indicates that the destination path should be interpreted as a folder to which the query will output multiple files. One parquet file will be written in parallel to the folder for each partition in the query. The next option `compression` set to `snappy` indicates that unless otherwise specified all columns should use the snappy compression codec. The option `compression::col1` sets an override, so that the column `col1` in the parquet file will use `ZSTD` compression codec with compression level `5`. In general, parquet option which support column specific settings can be specified with the syntax `OPTION::COLUMN.NESTED.PATH`. Review Comment: ```suggestion In this example, we write the entirety of `source_table` out to a folder of parquet files. The option `single_file_output` set to false, indicates that the destination path should be interpreted as a folder to which the query will output multiple files. One parquet file will be written in parallel to the folder for each partition in the query. The next option `compression` set to `snappy` indicates that unless otherwise specified all columns should use the snappy compression codec. The option `compression::col1` sets an override, so that the column `col1` in the parquet file will use `ZSTD` compression codec with compression level `5`. In general, the parquet option which supports column-specific settings can be specified with the syntax `OPTION::COLUMN.NESTED.PATH`. ``` ########## docs/source/user-guide/sql/write_options.md: ########## @@ -0,0 +1,131 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# Write Options + +DataFusion supports customizing how data is written out to disk as a result of a `COPY` or `INSERT INTO` query. There are a few special options, file format (e.g. CSV or parquet) specific options, and parquet column specific options. Options can also in some cases be specified in multiple ways with a set order of precedence. + +## Specifying Options and Order of Precedence + +Write related options can be specified in the following ways: + +- Session level config defaults +- `CREATE EXTERNAL TABLE` options +- `COPY` option tuples + +For a list of supported session level config defaults see [Configuration Settings](https://arrow.apache.org/datafusion/user-guide/configs.html). These defaults apply to all write operations but have the lowest level of precedence. + +If inserting to an external table, table specific write options can be specified when the table is created: + +```sql +CREATE EXTERNAL TABLE +my_table(a bigint, b bigint) +STORED AS csv +COMPRESSION TYPE gzip +WITH HEADER ROW +DELIMETER ';' +LOCATION '/test/location/my_csv_table/' +OPTIONS( +CREATE_LOCAL_PATH 'true', +NULL_VALUE 'NAN' +); +``` + +When running `INSERT INTO my_table ...`, the above specified options will be respected (gzip compression, special delimiter, and header row included). Note that compression, header, and delimeter settings can also be specified within the `OPTIONS` tuple list. Dedicated syntax within the SQL statement always takes precedence over arbitrary option tuples, so if both are specified the `OPTIONS` setting will be ignored. CREATE_LOCAL_PATH is a special option that indicates if DataFusion should create local file paths when writing new files if they do not already exist. This option is useful if you wish to create an external table from scratch, using only DataFusion SQL statements. Finally, NULL_VALUE is a CSV format specific option that determines how null values should be encoded within the CSV file. + +Finally, options can be passed when running a `COPY` command. + +```sql +COPY source_table +TO 'test/table_with_options' +(format parquet, +single_file_output false, +compression snappy, +'compression::col1' 'zstd(5)', +) +``` + +In this example, we write the entirety of `source_table` out to a folder of parquet files. The option `single_file_output` set to false, indicates that the destination path should be interpreted as a folder to which the query will output multiple files. One parquet file will be written in parallel to the folder for each partition in the query. The next option `compression` set to `snappy` indicates that unless otherwise specified all columns should use the snappy compression codec. The option `compression::col1` sets an override, so that the column `col1` in the parquet file will use `ZSTD` compression codec with compression level `5`. In general, parquet option which support column specific settings can be specified with the syntax `OPTION::COLUMN.NESTED.PATH`. + +## Available Options + +### COPY Specific Options + +The following special options are specific to the `COPY` query. + +| Option | Description | Default Value | +| ------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------- | +| SINGLE_FILE_OUTPUT | If true, COPY query will write output to a single file. Otherwise, multiple files will be written to a directory in parallel. | true | +| FORMAT | Specifies the file format COPY query will write out. If single_file_output is false or format cannot be inferred from file extension, then FORMAT must be specified. | N/A | Review Comment: ```suggestion | FORMAT | Specifies the file format COPY query will write out. If single_file_output is false or the format cannot be inferred from the file extension, then FORMAT must be specified. | N/A | ``` ########## docs/source/user-guide/sql/write_options.md: ########## @@ -0,0 +1,131 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# Write Options + +DataFusion supports customizing how data is written out to disk as a result of a `COPY` or `INSERT INTO` query. There are a few special options, file format (e.g. CSV or parquet) specific options, and parquet column specific options. Options can also in some cases be specified in multiple ways with a set order of precedence. + +## Specifying Options and Order of Precedence + +Write related options can be specified in the following ways: + +- Session level config defaults +- `CREATE EXTERNAL TABLE` options +- `COPY` option tuples + +For a list of supported session level config defaults see [Configuration Settings](https://arrow.apache.org/datafusion/user-guide/configs.html). These defaults apply to all write operations but have the lowest level of precedence. + +If inserting to an external table, table specific write options can be specified when the table is created: + +```sql +CREATE EXTERNAL TABLE +my_table(a bigint, b bigint) +STORED AS csv +COMPRESSION TYPE gzip +WITH HEADER ROW +DELIMETER ';' +LOCATION '/test/location/my_csv_table/' +OPTIONS( +CREATE_LOCAL_PATH 'true', +NULL_VALUE 'NAN' +); +``` + +When running `INSERT INTO my_table ...`, the above specified options will be respected (gzip compression, special delimiter, and header row included). Note that compression, header, and delimeter settings can also be specified within the `OPTIONS` tuple list. Dedicated syntax within the SQL statement always takes precedence over arbitrary option tuples, so if both are specified the `OPTIONS` setting will be ignored. CREATE_LOCAL_PATH is a special option that indicates if DataFusion should create local file paths when writing new files if they do not already exist. This option is useful if you wish to create an external table from scratch, using only DataFusion SQL statements. Finally, NULL_VALUE is a CSV format specific option that determines how null values should be encoded within the CSV file. + +Finally, options can be passed when running a `COPY` command. + +```sql +COPY source_table +TO 'test/table_with_options' +(format parquet, +single_file_output false, +compression snappy, +'compression::col1' 'zstd(5)', +) +``` + +In this example, we write the entirety of `source_table` out to a folder of parquet files. The option `single_file_output` set to false, indicates that the destination path should be interpreted as a folder to which the query will output multiple files. One parquet file will be written in parallel to the folder for each partition in the query. The next option `compression` set to `snappy` indicates that unless otherwise specified all columns should use the snappy compression codec. The option `compression::col1` sets an override, so that the column `col1` in the parquet file will use `ZSTD` compression codec with compression level `5`. In general, parquet option which support column specific settings can be specified with the syntax `OPTION::COLUMN.NESTED.PATH`. + +## Available Options + +### COPY Specific Options + +The following special options are specific to the `COPY` query. + +| Option | Description | Default Value | +| ------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------- | +| SINGLE_FILE_OUTPUT | If true, COPY query will write output to a single file. Otherwise, multiple files will be written to a directory in parallel. | true | +| FORMAT | Specifies the file format COPY query will write out. If single_file_output is false or format cannot be inferred from file extension, then FORMAT must be specified. | N/A | + +### CREATE EXTERNAL TABLE Specific Options + +The following special options are specific to creating an external table. + +| Option | Description | Default Value | +| ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------- | +| SINGLE_FILE | If true, indicates that this external table is backed by a single file. INSERT INTO queries will append to this file. | false | +| CREATE_LOCAL_PATH | If true, the folder or file backing this table will be created on the local file system if it does not already exist when running INSERT INTO queries. | false | +| INSERT_MODE | Determines if INSERT INTO queries should append to existing files or append new files to an existing directory. Valid values are append_to_file, append_new_files, and error. Note that "error" will block inserting data into this table. | CSV and JSON default to append_to_file. Parquet defaults to append_new_files | + +### JSON Format Specific Options + +The following options are available when writting JSON files. Note: if any unsupported option is specified, an error will be raised and the query will fail. + +| Option | Description | Default Value | +| ----------- | ---------------------------------------------------------------------------------------------------------------------------------- | ------------- | +| COMPRESSION | Sets the compression that should be applied to the entire JSON file. Supported values are GZIP, BZIP2, XZ, ZSTD, and UNCOMPRESSED. | UNCOMPRESSED | + +### CSV Format Sepcific Options + +The following options are available when writing CSV files. Note: if any unsupported options is specified an error will be raised and the query will fail. + +| Option | Description | Default Value | +| --------------- | --------------------------------------------------------------------------------------------------------------------------------- | ---------------- | +| COMPRESSION | Sets the compression that should be applied to the entire CSV file. Supported values are GZIP, BZIP2, XZ, ZSTD, and UNCOMPRESSED. | UNCOMPRESSED | +| HEADER | Sets if the CSV file should include column headers | false | +| DATE_FORMAT | Sets the format that dates should be encoded in within the CSV file | arrow-rs default | +| DATETIME_FORMAT | Sets the format that datetimes should be encoded in within the CSV file | arrow-rs default | +| TIME_FORMAT | Sets the format that times should be encoded in within the CSV file | arrow-rs default | +| RFC3339 | If true, uses RFC339 format for date and time encodings | arrow-rs default | +| NULL_VALUE | Sets the string which should be used to indicate null values within the CSV file. | arrow-rs default | +| DELIMETER | Sets the character which should be used as the column delimiter within the CSV file. | arrow-rs default | Review Comment: ```suggestion | DELIMITER | Sets the character which should be used as the column delimiter within the CSV file. | arrow-rs default | ``` ########## docs/source/user-guide/sql/write_options.md: ########## @@ -0,0 +1,131 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# Write Options + +DataFusion supports customizing how data is written out to disk as a result of a `COPY` or `INSERT INTO` query. There are a few special options, file format (e.g. CSV or parquet) specific options, and parquet column specific options. Options can also in some cases be specified in multiple ways with a set order of precedence. + +## Specifying Options and Order of Precedence + +Write related options can be specified in the following ways: + +- Session level config defaults +- `CREATE EXTERNAL TABLE` options +- `COPY` option tuples + +For a list of supported session level config defaults see [Configuration Settings](https://arrow.apache.org/datafusion/user-guide/configs.html). These defaults apply to all write operations but have the lowest level of precedence. + +If inserting to an external table, table specific write options can be specified when the table is created: + +```sql +CREATE EXTERNAL TABLE +my_table(a bigint, b bigint) +STORED AS csv +COMPRESSION TYPE gzip +WITH HEADER ROW +DELIMETER ';' +LOCATION '/test/location/my_csv_table/' +OPTIONS( +CREATE_LOCAL_PATH 'true', +NULL_VALUE 'NAN' +); +``` + +When running `INSERT INTO my_table ...`, the above specified options will be respected (gzip compression, special delimiter, and header row included). Note that compression, header, and delimeter settings can also be specified within the `OPTIONS` tuple list. Dedicated syntax within the SQL statement always takes precedence over arbitrary option tuples, so if both are specified the `OPTIONS` setting will be ignored. CREATE_LOCAL_PATH is a special option that indicates if DataFusion should create local file paths when writing new files if they do not already exist. This option is useful if you wish to create an external table from scratch, using only DataFusion SQL statements. Finally, NULL_VALUE is a CSV format specific option that determines how null values should be encoded within the CSV file. Review Comment: ```suggestion When running `INSERT INTO my_table ...`, the above specified options will be respected (gzip compression, special delimiter, and header row included). Note that compression, header, and delimiter settings can also be specified within the `OPTIONS` tuple list. Dedicated syntax within the SQL statement always takes precedence over arbitrary option tuples, so if both are specified the `OPTIONS` setting will be ignored. CREATE_LOCAL_PATH is a special option that indicates if DataFusion should create local file paths when writing new files if they do not already exist. This option is useful if you wish to create an external table from scratch, using only DataFusion SQL statements. Finally, NULL_VALUE is a CSV format specific option that determines how null values should be encoded within the CSV file. ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
