show clusters

src/Interpreters/InterpreterShowTablesQuery.cpp

@@ -8,6 +8,7 @@
 #include <Common/typeid_cast.h>
 #include <iomanip>
 #include <sstream>
+#include <iostream>
 
 
 namespace DB
@@ -33,6 +34,32 @@ String InterpreterShowTablesQuery::getRewrittenQuery()
     if (query.databases)
         return "SELECT name FROM system.databases";
 
+    /// SHOW CLUSTER/CLUSTERS 
+    if (query.clusters)
+    {
+        std::stringstream rewritten_query;
+	rewritten_query << "SELECT cluster FROM system.clusters";
+
+        if (!query.like.empty())
+	{
+	    rewritten_query << " WHERE cluster " << (query.not_like ? "NOT " : "") << "LIKE " << std::quoted(query.like, '\'');
+	}
+
+	if (query.limit_length)
+            rewritten_query << " LIMIT " << query.limit_length;
+
+	return rewritten_query.str();
+    }
+    else if (query.cluster)
+    {
+        std::stringstream rewritten_query;
+	rewritten_query << "SELECT * FROM system.clusters";
+
+        rewritten_query << " WHERE cluster = " << std::quoted(query.cluster_str, '\'');
+
+	return rewritten_query.str();
+    }
+
     if (query.temporary && !query.from.empty())
         throw Exception("The `FROM` and `TEMPORARY` cannot be used together in `SHOW TABLES`", ErrorCodes::SYNTAX_ERROR);
 

src/Parsers/ASTShowTablesQuery.cpp

@@ -2,7 +2,6 @@
 #include <Parsers/ASTShowTablesQuery.h>
 #include <Common/quoteString.h>
 
-
 namespace DB
 {
 
@@ -20,6 +19,24 @@ void ASTShowTablesQuery::formatQueryImpl(const FormatSettings & settings, Format
     {
         settings.ostr << (settings.hilite ? hilite_keyword : "") << "SHOW DATABASES" << (settings.hilite ? hilite_none : "");
     }
+    else if (clusters)
+    {
+        settings.ostr << (settings.hilite ? hilite_keyword : "") << "SHOW CLUSTERS" << (settings.hilite ? hilite_none : "");
+        if (!like.empty())
+            settings.ostr << (settings.hilite ? hilite_keyword : "") << (not_like ? " NOT" : "") << " LIKE " << (settings.hilite ? hilite_none : "")
+                << std::quoted(like, '\'');
+
+        if (limit_length)
+        {
+            settings.ostr << (settings.hilite ? hilite_keyword : "") << " LIMIT " << (settings.hilite ? hilite_none : "");
+            limit_length->formatImpl(settings, state, frame);
+        }
+    }
+    else if (cluster)
+    {
+        settings.ostr << (settings.hilite ? hilite_keyword : "") << "SHOW CLUSTER" << (settings.hilite ? hilite_none : "");
+	settings.ostr << " " << backQuoteIfNeed(cluster_str);
+    }
     else
     {
         settings.ostr << (settings.hilite ? hilite_keyword : "") << "SHOW " << (temporary ? "TEMPORARY " : "") <<

src/Parsers/ASTShowTablesQuery.h

@@ -9,14 +9,17 @@ namespace DB
 {
 
 
-/** Query SHOW TABLES or SHOW DATABASES
+/** Query SHOW TABLES or SHOW DATABASES or SHOW CLUSTERS
   */
 class ASTShowTablesQuery : public ASTQueryWithOutput
 {
 public:
     bool databases{false};
+    bool clusters{false};
+    bool cluster{false};
     bool dictionaries{false};
     bool temporary{false};
+    String cluster_str;
     String from;
     String like;
     bool not_like{false};

src/Parsers/ParserShowTablesQuery.cpp

@@ -6,8 +6,10 @@
 #include <Parsers/ParserShowTablesQuery.h>
 #include <Parsers/ExpressionElementParsers.h>
 #include <Parsers/ExpressionListParsers.h>
+#include <Parsers/parseIdentifierOrStringLiteral.h>
 
 #include <Common/typeid_cast.h>
+#include <common/logger_useful.h>
 
 
 namespace DB
@@ -20,6 +22,8 @@ bool ParserShowTablesQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expec
     ParserKeyword s_temporary("TEMPORARY");
     ParserKeyword s_tables("TABLES");
     ParserKeyword s_databases("DATABASES");
+    ParserKeyword s_clusters("CLUSTERS");
+    ParserKeyword s_cluster("CLUSTER");
     ParserKeyword s_dictionaries("DICTIONARIES");
     ParserKeyword s_from("FROM");
     ParserKeyword s_in("IN");
@@ -43,6 +47,36 @@ bool ParserShowTablesQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expec
     {
         query->databases = true;
     }
+    else if (s_clusters.ignore(pos))
+    {
+        query->clusters = true;
+
+        if (s_not.ignore(pos, expected))
+            query->not_like = true;
+
+        if (s_like.ignore(pos, expected))
+        {
+            if (!like_p.parse(pos, like, expected))
+                return false;
+        }
+        else if (query->not_like)
+            return false;
+        if (s_limit.ignore(pos, expected))
+        {
+            if (!exp_elem.parse(pos, query->limit_length, expected))
+                return false;
+        }
+    }
+    else if (s_cluster.ignore(pos))
+    {
+        query->cluster = true;
+
+	String cluster_str;
+	if (!parseIdentifierOrStringLiteral(pos, expected, cluster_str))
+	    return false;
+
+	query->cluster_str = std::move(cluster_str);
+    }
     else
     {
         if (s_temporary.ignore(pos))

src/Parsers/ParserShowTablesQuery.h

@@ -14,7 +14,7 @@ namespace DB
 class ParserShowTablesQuery : public IParserBase
 {
 protected:
-    const char * getName() const override { return "SHOW [TEMPORARY] TABLES|DATABASES [[NOT] LIKE 'str'] [LIMIT expr]"; }
+    const char * getName() const override { return "SHOW [TEMPORARY] TABLES|DATABASES|CLUSTERS|CLUSTER 'name' [[NOT] LIKE 'str'] [LIMIT expr]"; }
     bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) override;
 };
 

tests/queries/0_stateless/01293_show_create_cluster.sql

@@ -0,0 +1,3 @@
+show clusters;
+show clusters like 'test%' limit 1;
+show cluster 'test_shard_localhost';