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 <jianq...@cs.wisc.edu>
Date: 2017-08-04T21:49:45Z
Add "COPY TO" operator for exporting data from Quickstep.
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