GitHub user xwu0226 opened a pull request:
https://github.com/apache/spark/pull/12132
Show create table
## What changes were proposed in this pull request?
1. add `SHOW CREATE TABLE tableIdentifier` in SqlBase.g4 file
2. create a `RunnableCommand ` class for `ShowCreateTableCommand`, that
invokes `SessionCatalog.generateTableDDL`
3. add `generateTableDDL ` method in `SessionCatalog `and override it in
`HiveSessionCatalog`.
4. `HiveSessionCatalog.generateTableDDL` is to create DDL for metastore
tables. and for tempTables in Spark, it may not be quite practical. For now, we
throw exception in `SessionCatalog.generateTableDDL`. If the community thinks
it is also necessary, we can implement this later.
5. `HiveSessionCatalog.generateTableDDL` branches out to generate Hive
syntax DDL for hive tables, while it is also supposed to branch out to generate
DataSource syntax DDL for datasource tables.
TODO:
1. implement generate DDL for DataSource table with DataSource syntax DDL
like "**USING**... **OPTIONS**..."
2. Currently for hive table DDL syntax, there are also a few potential gaps
like sortBucketSpec, skewSpec, storageHandler case, etc. that are not quite
supported in `CatalogTable`.. we may need to discuss whether we need to
complete this.
3. complete the unit testcase with checkAnswer.. Right now, it put the
show() to display what it generates.
## How was this patch tested?
unite tests with manual observation so far. Testcases will be completed as
TODO
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/xwu0226/spark show_create_table_1
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/12132.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 #12132
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commit efff74e90548ff8b2d031ac03d88e61677c73b78
Author: xin Wu <[email protected]>
Date: 2016-04-02T01:46:16Z
show create table DDL -- hive metastore table
commit c7ae9f434725a97d1beb0c2d3e4e781b6df12f61
Author: xin Wu <[email protected]>
Date: 2016-04-02T06:01:46Z
update upon review
commit 850edbe4654c10d0c95689447121b7686229dbf3
Author: xin Wu <[email protected]>
Date: 2016-04-02T18:19:26Z
ignoring sqlContext temp table and considering datasource table ddl
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