GitHub user HeartSaVioR opened a pull request:
https://github.com/apache/storm/pull/1681
STORM-1444 Support EXPLAIN statement in StormSQL
* when '--explain' is specified to topology name, activate explain mode
* when explain mode is activated, it analyzes each query statement, and
shows query plan
* it doesn't submit topologies
* Showing plan is provided by Calcite: it just uses that feature
As I also described to the doc, query plan for below query
```
INSERT INTO LARGE_ORDERS SELECT ID, UNIT_PRICE * QUANTITY AS TOTAL FROM
ORDERS
WHERE UNIT_PRICE * QUANTITY > 50
```
is shown as:
```
LogicalTableModify(table=[[LARGE_ORDERS]], operation=[INSERT],
updateColumnList=[[]], flattened=[true]), id = 8
LogicalProject(ID=[$0], TOTAL=[*($1, $2)]), id = 7
LogicalFilter(condition=[>(*($1, $2), 50)]), id = 6
EnumerableTableScan(table=[[ORDERS]]), id = 5
```
FYI, $0 is column index 0 (starting from 0), and so on. Expression is
printed as prefix notation.
Calcite just provides this functionality, though I'm not clear whether this
is friendly (acceptable by end-user) or not.
There's staled issue from Calcite
([CALCITE-155](https://issues.apache.org/jira/browse/CALCITE-155)) for
displaying actual column names/aliases in explain plan.
Please have a look and share your opinion about this.
Thanks in advance!
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/HeartSaVioR/storm STORM-1444
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/storm/pull/1681.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 #1681
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