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From jianqiao <...@git.apache.org>
Subject [GitHub] incubator-quickstep pull request #291: Add "COPY TO" operator for exporting ...
Date Wed, 30 Aug 2017 16:26:40 GMT
GitHub user jianqiao opened a pull request:

    https://github.com/apache/incubator-quickstep/pull/291

    Add "COPY TO" operator for exporting data from Quickstep.

    This PR adds support for the "COPY TO" statement for exporting tables from Quickstep.
Two formats `TEXT` and `CSV` are supported.
    
    The current available copy options are:
    - `FORMAT`: Format of the output file, either `TEXT` or `CSV`.
    - `DELIMITER`: Separator character of the fields.
    - `HEADER`: Whether to add table header. For `CSV` format only.
    - `QUOTE`: The quote character. For `CSV` format only.
    - `ESCAPE_STRINGS`: Whether to escape special characters. For `TEXT` format only.
    - `NULL_STRING`: The string representation of the `NULL` value.
    
    See the example queries and results [here](https://github.com/apache/incubator-quickstep/blob/a036acb446f137fea263ae218ef12f337f5bc1a1/query_optimizer/tests/execution_generator/Copy.test).

    
    Note that some convenient features are also provided:
    - Export the result table from a query.
    ```
    -- (1) --
    COPY
      SELECT x FROM r
    TO 'data.txt';
    
    -- (2) --
    WITH s(v) AS (
      SELECT MIN(y) FROM r GROUP BY x
    )
    COPY
      SELECT AVG(v) FROM s
    TO 'results.csv';
    ```
    
    - Print to standard output/error stream, e.g.
    ```
    -- (1) --
    COPY r TO stdout;
    
    -- (2) --
    COPY 
      SELECT x FROM r
    TO stderr;
    ```

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/apache/incubator-quickstep copy-to

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/incubator-quickstep/pull/291.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #291
    
----
commit a036acb446f137fea263ae218ef12f337f5bc1a1
Author: Jianqiao Zhu <jianqiao@cs.wisc.edu>
Date:   2017-08-04T21:49:45Z

    Add "COPY TO" operator for exporting data from Quickstep.

----


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