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https://issues.apache.org/jira/browse/DRILL-7168?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16926534#comment-16926534
]
ASF GitHub Bot commented on DRILL-7168:
---------------------------------------
vvysotskyi commented on pull request #1850: DRILL-7168: Implement ALTER SCHEMA
ADD / REMOVE commands
URL: https://github.com/apache/drill/pull/1850#discussion_r322688169
##########
File path: exec/java-exec/src/main/codegen/includes/parserImpls.ftl
##########
@@ -534,6 +534,110 @@ SqlNode SqlDescribeSchema() :
)
}
+/**
+* Parses ALTER SCHEMA statements:
+*
+* ALTER SCHEMA
+* (FOR TABLE dfs.tmp.nation | PATH '/tmp/schema.json')
+* ADD [OR REPLACE]
+* [COLUMNS (col1 int, col2 varchar)]
+* [PROPERTIES ('prop1'='val1', 'prop2'='val2')]
+*
+* ALTER SCHEMA
+* (FOR TABLE dfs.tmp.nation | PATH '/tmp/schema.json')
+* REMOVE
+* [COLUMNS (`col1`, `col2`)]
+* [PROPERTIES ('prop1', 'prop2')]
+*/
+SqlNode SqlAlterSchema() :
+{
+ SqlParserPos pos;
+ SqlIdentifier table = null;
+ SqlNode path = null;
+}
+{
+ <ALTER> { pos = getPos(); }
+ <SCHEMA>
+ (
+ <FOR> <TABLE> { table = CompoundIdentifier(); }
+ |
+ <PATH> { path = StringLiteral(); }
+ )
+ (
+ <ADD> { return SqlAlterSchemaAdd(pos, table, path); }
+ |
+ <REMOVE> { return SqlAlterSchemaRemove(pos, table, path); }
+ )
+}
+
+SqlNode SqlAlterSchemaAdd(SqlParserPos pos, SqlIdentifier table, SqlNode path)
:
+{
+ boolean replace = false;
+ SqlCharStringLiteral schema = null;
+ SqlNodeList properties = null;
+}
+{
+ [ <OR> <REPLACE> { replace = true; } ]
+ [ <COLUMNS> { schema = ParseSchema(); } ]
+ [
+ <PROPERTIES> <LPAREN>
+ {
+ properties = new SqlNodeList(getPos());
+ addProperty(properties);
+ }
+ (
+ <COMMA> { addProperty(properties); }
+ )*
+ <RPAREN>
+ ]
+ {
+ if (schema == null && properties == null) {
+ throw new ParseException("ALTER SCHEMA ADD command must have at
least <COLUMNS> or <PROPERTIES> keyword indicated.");
+ }
+ return new SqlSchema.Add(pos, table, path,
SqlLiteral.createBoolean(replace, getPos()), schema, properties);
+ }
+}
+
+SqlCharStringLiteral ParseSchema() :
Review comment:
Ok, thanks a lot for a detailed explanation.
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> Implement ALTER SCHEMA ADD / REMOVE COLUMN / PROPERTY commands
> --------------------------------------------------------------
>
> Key: DRILL-7168
> URL: https://issues.apache.org/jira/browse/DRILL-7168
> Project: Apache Drill
> Issue Type: Sub-task
> Reporter: Arina Ielchiieva
> Assignee: Arina Ielchiieva
> Priority: Major
> Labels: doc-impacting
> Fix For: 1.17.0
>
>
> By [~Paul.Rogers]:
> {quote}
> Sooner or later users are going to ask for a command to update just the
> properties, or just add or remove a column, without having to spell out the
> entire new schema. ALTER TABLE SCHEMA ADD/REMOVE COLUMN/PROPERTY ...
> {quote}
> Syntax:
> {code:sql}
> alter schema
> (for table dfs.tmp.nation | path '/tmp/schema.json')
> add [or replace]
> [columns (col1 int, col2 varchar)]
> [properties ('prop1'='val1', 'prop2'='val2')]
> {code}
> Add command will fail if column or property with the same name exists, unless
> OR REPLACE keywords are indicated.
> Add command will fail, if schema file does not exit.
> {code:sql}
> alter schema
> (for table dfs.tmp.nation | path '/tmp/schema.json')
> remove
> [columns (`col1`, `col2`)]
> [properties ('prop1', 'prop2')]
> {code}
> Remove command won't fail if column or property does not exist but will fail
> if schema file is absent.
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