describe partitions statement

CHANGELOG

@@ -12,6 +12,9 @@ EventQL v0.5.0 beta;
 
   * Added new frames to native protocol: ACK, INSERT, REPL_INSERT
 
+  * Added the DESCRIBE PARTITIONS table statement to obtain information about
+    the partitions of a table
+
   * Added the following new configuration options: server.disk_capacity,
     server.load_limit_{soft,hard}, server.partitions_loading_limit_{soft,hard},
     server.loadinfo_publish_interval, server.noalloc

doc/sql/statements.md

@@ -10,5 +10,6 @@ The following SQL statements are currently supported.
   - [ALTER TABLE](./alter-table/) is used to modify an existing table's schema
   - [DROP TABLE](./drop-table/) is used to drop an existing table
   - [DESCRIBE](./describe/) shows the structure of a table
+  - [DESCRIBE PARTITIONS](./describe-partitions/) list the table's partitions
   - [SHOW TABLES](./show-tables/) lists the tables in a database
 

doc/sql/statements/describe.md

@@ -3,4 +3,3 @@
 
     DESCRIBE table_name
 
-

doc/sql/statements/describe_partitions.md

@@ -0,0 +1,20 @@
+5.2.7 DESCRIBE PARTITIONS
+===============================
+
+    DESCRIBE PARTITIONS table_name
+
+
+
+DESCRIBE PARTITIONS displays information about all partitions of the table.
+
+
+Example
+
+    evql> DESCRIBE PARTITIONS sensors;
+
+    +------------------------------------------+------------------------+---------------------+
+    | Partition id                             | Keyrange Begin         | Servers             |
+    +------------------------------------------+------------------------+---------------------+
+    | 48127ec1a9c0812af6ba0240013c99baea40e22e | 2016-02-08 00:00:00    | node1, node3, node4 |
+    +------------------------------------------+------------------------+---------------------+
+

doc/toc.yaml

@@ -634,6 +634,13 @@
             visible_in_menu: true
             visible_in_toc: true
             source: "/sql/statements/describe.md"
+          -
+            url: "/sql/statements/describe-partitions"
+            title: "DESCRIBE PARTITIONS"
+            type: page
+            visible_in_menu: true
+            visible_in_toc: true
+            source: "/sql/statements/describe_partitions.md"
           -
             url: "/sql/statements/show-tables"
             title: "SHOW TABLES"

src/Makefile.am

@@ -614,6 +614,8 @@ EVQL_CORE_SOURCES_ = \
     eventql/sql/expressions/string.h \
     eventql/sql/expressions/table/describe_table.cc \
     eventql/sql/expressions/table/describe_table.h \
+    eventql/sql/expressions/table/describe_partitions.cc \
+    eventql/sql/expressions/table/describe_partitions.h \
     eventql/sql/expressions/table/groupby.cc \
     eventql/sql/expressions/table/groupby.h \
     eventql/sql/expressions/table/limit.cc \
@@ -718,6 +720,8 @@ EVQL_CORE_SOURCES_ = \
     eventql/sql/qtree/nodes/insert_into.h \
     eventql/sql/qtree/nodes/insert_json.cc \
     eventql/sql/qtree/nodes/insert_json.h \
+    eventql/sql/qtree/nodes/describe_partitions.cc \
+    eventql/sql/qtree/nodes/describe_partitions.h \
     eventql/sql/qtree/qtree_coder.cc \
     eventql/sql/qtree/qtree_coder.h \
     eventql/sql/qtree/qtree_coder_impl.h \

src/eventql/db/table_info.h

@@ -30,4 +30,10 @@
 
 namespace eventql {
 
+struct TablePartitionInfo {
+  std::vector<std::string> server_ids;
+  std::string partition_id;
+  std::string keyrange_begin;
+};
+
 }

src/eventql/db/table_service.cc

@@ -438,6 +438,51 @@ void TableService::listTables(
   });
 }
 
+Status TableService::listPartitions(
+    const String& db_namespace,
+    const String& table_name,
+    Function<void (const TablePartitionInfo& partition)> fn) const {
+  auto table = dbctx_->partition_map->findTable(db_namespace, table_name);
+  MetadataClient metadata_client(dbctx_->config_directory);
+  MetadataFile metadata_file;
+  auto rc = metadata_client.fetchLatestMetadataFile(
+      db_namespace,
+      table_name,
+      &metadata_file);
+
+  if (!rc.isSuccess()) {
+    return rc;
+  }
+
+  for (const auto& e : metadata_file.getPartitionMap()) {
+    TablePartitionInfo p_info;
+    p_info.partition_id = e.partition_id.toString();
+
+    for (const auto& s : e.servers) {
+      p_info.server_ids.emplace_back(s.server_id);
+    }
+
+    String keyrange;
+    switch (metadata_file.getKeyspaceType()) {
+      case KEYSPACE_UINT64: {
+        uint64_t keyrange_uint = -1;
+        memcpy((char*) &keyrange_uint, e.begin.data(), sizeof(e.begin));
+        p_info.keyrange_begin = keyrange_uint > -1 ?
+            UnixTime(keyrange_uint).toString() : "";
+        break;
+      }
+      case KEYSPACE_STRING: {
+        p_info.keyrange_begin = e.begin;
+        break;
+      }
+    }
+
+    fn(p_info);
+  }
+
+  return Status::success();
+}
+
 ReturnCode TableService::insertRecord(
     const String& tsdb_namespace,
     const String& table_name,

src/eventql/db/table_service.h

@@ -36,6 +36,8 @@
 #include <eventql/db/record_envelope.pb.h>
 #include <eventql/db/partition_map.h>
 #include <eventql/db/shredded_record.h>
+#include <eventql/db/metadata_file.h>
+#include <eventql/sql/TableInfo.h>
 #include <eventql/config/config_directory.h>
 
 #include "eventql/eventql.h"
@@ -85,6 +87,11 @@ class TableService {
       const String& tsdb_namespace,
       Function<void (const TableDefinition& table)> fn) const;
 
+  Status listPartitions(
+    const String& db_namespace,
+    const String& table_name,
+    Function<void (const TablePartitionInfo& partition)> fn) const;
+
   // insert one record
   ReturnCode insertRecord(
       const String& tsdb_namespace,

src/eventql/server/sql/table_provider.cc

@@ -510,6 +510,15 @@ void TSDBTableProvider::listTables(
       });
 }
 
+Status TSDBTableProvider::listPartitions(
+    const String& table_name,
+    Function<void (const TablePartitionInfo& partition)> fn) const {
+  return table_service_->listPartitions(
+      tsdb_namespace_,
+      table_name,
+      fn);
+}
+
 Option<csql::TableInfo> TSDBTableProvider::describe(
     const String& table_name) const {
   auto table_ref = TSDBTableRef::parse(table_name);

src/eventql/server/sql/table_provider.h

@@ -62,6 +62,10 @@ struct TSDBTableProvider : public csql::TableProvider {
   void listTables(
       Function<void (const csql::TableInfo& table)> fn) const override;
 
+  Status listPartitions(
+      const String& table_name,
+      Function<void (const TablePartitionInfo& partition)> fn) const override;
+
   Option<csql::TableInfo> describe(const String& table_name) const override;
 
   Status createTable(const csql::CreateTableNode& req) override;

src/eventql/sql/expressions/table/describe_partitions.cc

@@ -0,0 +1,89 @@
+/**
+ * Copyright (c) 2016 DeepCortex GmbH <legal@eventql.io>
+ * Authors:
+ *   - Laura Schlimmer <laura@eventql.io>
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License ("the license") as
+ * published by the Free Software Foundation, either version 3 of the License,
+ * or any later version.
+ *
+ * In accordance with Section 7(e) of the license, the licensing of the Program
+ * under the license does not imply a trademark license. Therefore any rights,
+ * title and interest in our trademarks remain entirely with us.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the license for more details.
+ *
+ * You can be released from the requirements of the license by purchasing a
+ * commercial license. Buying such a license is mandatory as soon as you develop
+ * commercial activities involving this program without disclosing the source
+ * code of your own applications
+ */
+#include <eventql/sql/expressions/table/describe_partitions.h>
+#include <eventql/sql/transaction.h>
+
+namespace csql {
+
+DescribePartitionsExpression::DescribePartitionsExpression(
+    Transaction* txn,
+    const String& table_name) :
+    txn_(txn),
+    table_name_(table_name),
+    counter_(0) {}
+
+ScopedPtr<ResultCursor> DescribePartitionsExpression::execute() {
+  txn_->getTableProvider()->listPartitions(
+      table_name_,
+      [this] (const eventql::TablePartitionInfo& p_info) {
+    rows_.emplace_back(p_info);
+  });
+
+  return mkScoped(
+      new DefaultResultCursor(
+          kNumColumns,
+          std::bind(
+              &DescribePartitionsExpression::next,
+              this,
+              std::placeholders::_1,
+              std::placeholders::_2)));
+
+}
+
+size_t DescribePartitionsExpression::getNumColumns() const {
+  return kNumColumns;
+}
+
+bool DescribePartitionsExpression::next(SValue* row, size_t row_len) {
+  if (counter_ < rows_.size()) {
+    const auto& col = rows_[counter_];
+    switch (row_len) {
+      default:
+      case 3: {
+        std::string server_ids;
+        for (size_t i = 0; i < col.server_ids.size(); ++i) {
+          if (i > 0) {
+            server_ids += ", ";
+          }
+          server_ids += col.server_ids[i];
+        }
+        row[2] = SValue::newString(server_ids); //Server id
+      }
+      case 2:
+        row[1] = SValue::newString(col.keyrange_begin); //Keyrange begin
+      case 1:
+        row[0] = SValue::newString(col.partition_id); //Partition id
+      case 0:
+        break;
+    }
+
+    ++counter_;
+    return true;
+  } else {
+    return false;
+  }
+}
+
+} //csql
+

src/eventql/sql/expressions/table/describe_partitions.h

@@ -0,0 +1,56 @@
+/**
+ * Copyright (c) 2016 DeepCortex GmbH <legal@eventql.io>
+ * Authors:
+ *   - Laura Schlimmer <laura@eventql.io>
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License ("the license") as
+ * published by the Free Software Foundation, either version 3 of the License,
+ * or any later version.
+ *
+ * In accordance with Section 7(e) of the license, the licensing of the Program
+ * under the license does not imply a trademark license. Therefore any rights,
+ * title and interest in our trademarks remain entirely with us.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the license for more details.
+ *
+ * You can be released from the requirements of the license by purchasing a
+ * commercial license. Buying such a license is mandatory as soon as you develop
+ * commercial activities involving this program without disclosing the source
+ * code of your own applications
+ */
+#pragma once
+#include "eventql/eventql.h"
+#include <eventql/util/stdtypes.h>
+#include <eventql/sql/qtree/ShowTablesNode.h>
+#include <eventql/sql/runtime/tablerepository.h>
+
+namespace csql {
+
+class DescribePartitionsExpression : public TableExpression {
+public:
+
+  static const size_t kNumColumns = 3;
+
+  DescribePartitionsExpression(
+      Transaction* txn,
+      const String& table_name);
+
+  ScopedPtr<ResultCursor> execute() override;
+
+  size_t getNumColumns() const override;
+
+protected:
+
+  bool next(SValue* row, size_t row_len);
+
+  Transaction* txn_;
+  String table_name_;
+  Vector<eventql::TablePartitionInfo> rows_;
+  size_t counter_;
+};
+
+} //csql
+

src/eventql/sql/parser/astnode.cc

@@ -333,6 +333,9 @@ void ASTNode::debugPrint(int indent /* = 0 */) const {
     case T_DESCRIBE_TABLE:
       printf("- T_DESCRIBE_TABLE");
       break;
+    case T_DESCRIBE_PARTITIONS:
+      printf("- T_DESCRIBE_PARTITIONS");
+      break;
     case T_EXPLAIN_QUERY:
       printf("- T_EXPLAIN_QUERY");
       break;

src/eventql/sql/parser/astnode.h

@@ -95,6 +95,7 @@ class ASTNode {
 
     T_SHOW_TABLES,
     T_DESCRIBE_TABLE,
+    T_DESCRIBE_PARTITIONS,
     T_EXPLAIN_QUERY,
     T_CREATE_TABLE,
     T_COLUMN_LIST,

src/eventql/sql/parser/parser.cc

@@ -880,6 +880,8 @@ ASTNode* Parser::explainStatement() {
   switch (cur_token_->getType()) {
     case Token::T_SELECT:
       return explainQueryStatement();
+    case Token::T_PARTITIONS:
+      return describePartitionsStatement();
     default:
       return describeTableStatement();
   }
@@ -892,6 +894,14 @@ ASTNode* Parser::explainQueryStatement() {
   return stmt;
 }
 
+ASTNode* Parser::describePartitionsStatement() {
+  consumeToken();
+  auto stmt = new ASTNode(ASTNode::T_DESCRIBE_PARTITIONS);
+  stmt->appendChild(tableName());
+  consumeIf(Token::T_SEMICOLON);
+  return stmt;
+}
+
 ASTNode* Parser::describeTableStatement() {
   auto stmt = new ASTNode(ASTNode::T_DESCRIBE_TABLE);
   stmt->appendChild(tableName());

src/eventql/sql/parser/parser.h

@@ -126,6 +126,7 @@ class Parser {
   ASTNode* showStatement();
   ASTNode* explainStatement();
   ASTNode* explainQueryStatement();
+  ASTNode* describePartitionsStatement();
   ASTNode* describeTableStatement();
 
   ASTNode* fromClause();

src/eventql/sql/parser/token.cc

@@ -126,6 +126,7 @@ const char* Token::getTypeName(kTokenType type) {
     case T_SHOW: return "T_SHOW";
     case T_DESCRIBE: return "T_DESCRIBE";
     case T_EXPLAIN: return "T_EXPLAIN";
+    case T_PARTITIONS: return "T_PARTITIONS";
     case T_EOF: return "T_EOF";
     case T_DRAW: return "T_DRAW";
     case T_LINECHART: return "T_LINECHART";

src/eventql/sql/parser/token.h

@@ -92,6 +92,7 @@ class Token {
     T_SHOW,
     T_DESCRIBE,
     T_EXPLAIN,
+    T_PARTITIONS,
     T_PRIMARY,
     T_KEY,
     T_REPEATED,