paul-rogers commented on a change in pull request #2030: Update docs for
Metastore to point that all format plugins are supported
URL: https://github.com/apache/drill/pull/2030#discussion_r394576664
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File path: _docs/sql-reference/sql-commands/021-create-schema.md
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@@ -604,8 +608,32 @@ STATEMENT format displays the schema in a form compatible
with the CREATE OR REP
|
+--------------------------------------------------------------------------+
+### Altering Schema for a Table
+Table schema may be updated using the `ALTER SCHEMA` commands.
+
+The syntax for the command to add (or replace) columns / properties is the
following:
+
+ ALTER SCHEMA
+ (FOR TABLE dfs.tmp.nation | PATH '/tmp/schema.json')
+ ADD [OR REPLACE]
+ [COLUMNS (col1 int, col2 varchar)]
+ [PROPERTIES ('prop1'='val1', 'prop2'='val2')]
+
+Add command will fail if column or property with the same name exists, unless
`OR REPLACE` keywords are indicated.
Review comment:
`ALTER SCHEMA` modifies an existing schema file; it will fail if the schema
file does not exist. (Use `CREATE SCHEMA` to create a new schema file.)
To prevent accidental changes, the `ALTER SCHEMA ... ADD` command will fail
if the requested column or property already exists. Use the `OR REPLACE` clause
to modify an existing column or property.
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