Drop table

src/observer/sql/executor/command_executor.cpp

@@ -18,6 +18,7 @@ See the Mulan PSL v2 for more details. */
 #include "sql/executor/create_index_executor.h"
 #include "sql/executor/create_table_executor.h"
 #include "sql/executor/desc_table_executor.h"
+#include "sql/executor/drop_table_executor.h"
 #include "sql/executor/help_executor.h"
 #include "sql/executor/load_data_executor.h"
 #include "sql/executor/set_variable_executor.h"
@@ -42,6 +43,11 @@ RC CommandExecutor::execute(SQLStageEvent *sql_event)
       rc = executor.execute(sql_event);
     } break;
 
+    case StmtType::DROP_TABLE: {
+      DropTableExecutor executor;
+      rc = executor.execute(sql_event);
+    } break;
+
     case StmtType::DESC_TABLE: {
       DescTableExecutor executor;
       rc = executor.execute(sql_event);

src/observer/sql/executor/drop_table_executor.cpp

@@ -0,0 +1,25 @@
+#include "sql/executor/drop_table_executor.h"
+
+#include "common/log/log.h"
+#include "event/session_event.h"
+#include "event/sql_event.h"
+#include "session/session.h"
+#include "sql/stmt/drop_table_stmt.h"
+#include "storage/db/db.h"
+
+RC DropTableExecutor::execute(SQLStageEvent *sql_event)
+{
+  Stmt    *stmt    = sql_event->stmt();
+  Session *session = sql_event->session_event()->session();
+  ASSERT(stmt->type() == StmtType::DROP_TABLE,
+      "drop table executor can not run this command: %d",
+      static_cast<int>(stmt->type()));
+
+  DropTableStmt *drop_table_stmt = static_cast<DropTableStmt *>(stmt);
+
+  const char *table_name = drop_table_stmt->table_name().c_str();
+  RC rc = session->get_current_db()->drop_table(table_name);
+
+  return rc;
+}
+

src/observer/sql/executor/drop_table_executor.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "common/rc.h"
+
+class SQLStageEvent;
+
+/**
+ * @brief 删除表的执行器
+ * @ingroup Executor
+ */
+class DropTableExecutor
+{
+public:
+  DropTableExecutor()          = default;
+  virtual ~DropTableExecutor() = default;
+
+  RC execute(SQLStageEvent *sql_event);
+};
+

src/observer/sql/stmt/drop_table_stmt.cpp

@@ -0,0 +1,11 @@
+#include "common/log/log.h"
+#include "common/types.h"
+#include "sql/stmt/drop_table_stmt.h"
+#include "event/sql_debug.h"
+
+RC DropTableStmt::create(Db *db, const DropTableSqlNode &drop_table, Stmt *&stmt)
+{
+  stmt = new DropTableStmt(drop_table.relation_name);
+  sql_debug("create table statement: table name %s", drop_table.relation_name.c_str());
+  return RC::SUCCESS;
+}

src/observer/sql/stmt/drop_table_stmt.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <string>
+
+#include "sql/stmt/stmt.h"
+
+class Db;
+
+/**
+ * @brief 表示删除表的语句
+ * @ingroup Statement
+ * @details 虽然解析成了stmt，但是与原始的SQL解析后的数据也差不多
+ */
+class DropTableStmt : public Stmt
+{
+public:
+  DropTableStmt(const std::string &table_name) : table_name_(table_name) {}
+  virtual ~DropTableStmt() = default;
+
+  StmtType type() const override { return StmtType::DROP_TABLE; }
+
+  const std::string    &table_name() const { return table_name_; }
+
+  //TODO:
+  static RC            create(Db *db, const DropTableSqlNode &create_table, Stmt *&stmt);
+
+private:
+  std::string                  table_name_;
+};
+
+

src/observer/sql/stmt/stmt.cpp

@@ -17,6 +17,7 @@ See the Mulan PSL v2 for more details. */
 #include "sql/stmt/calc_stmt.h"
 #include "sql/stmt/create_index_stmt.h"
 #include "sql/stmt/create_table_stmt.h"
+#include "sql/stmt/drop_table_stmt.h"
 #include "sql/stmt/delete_stmt.h"
 #include "sql/stmt/desc_table_stmt.h"
 #include "sql/stmt/exit_stmt.h"
@@ -71,6 +72,10 @@ RC Stmt::create_stmt(Db *db, ParsedSqlNode &sql_node, Stmt *&stmt)
       return CreateTableStmt::create(db, sql_node.create_table, stmt);
     }
 
+    case SCF_DROP_TABLE: {
+      return DropTableStmt::create(db, sql_node.drop_table, stmt);
+    }
+
     case SCF_DESC_TABLE: {
       return DescTableStmt::create(db, sql_node.desc_table, stmt);
     }

src/observer/storage/db/db.cpp

@@ -161,6 +161,24 @@ RC Db::create_table(const char *table_name, span<const AttrInfoSqlNode> attribut
   return RC::SUCCESS;
 }
 
+RC Db::drop_table(const char *table_name) {
+  RC rc = RC::SUCCESS;
+
+  auto table_it = opened_tables_.find(table_name);
+  // check table_name
+  if (table_it == opened_tables_.end()) {
+    LOG_WARN("%s has not been opened.", table_name);
+    return RC::SCHEMA_TABLE_NOT_EXIST;
+  }
+
+  string table_file_path = table_meta_file(path_.c_str(), table_name);
+  Table *table           = table_it->second;
+  opened_tables_.erase(table_it);
+
+  Table::drop(table);
+  return rc;
+}
+
 Table *Db::find_table(const char *table_name) const
 {
   unordered_map<string, Table *>::const_iterator iter = opened_tables_.find(table_name);

src/observer/storage/db/db.h

@@ -66,6 +66,12 @@ class Db
   RC create_table(const char *table_name, span<const AttrInfoSqlNode> attributes,
       const StorageFormat storage_format = StorageFormat::ROW_FORMAT);
 
+  /**
+   * @brief 删除一个表
+   * @param table_name 表名
+   */
+  RC drop_table(const char *table_name);
+
   /**
    * @brief 根据表名查找表
    */

src/observer/storage/table/table.cpp

@@ -127,6 +127,23 @@ RC Table::create(Db *db, int32_t table_id, const char *path, const char *name, c
   return rc;
 }
 
+RC Table::drop(Table *table) {
+  string base_dir = table->base_dir_;
+  string name     = table->name();
+  string path     = table_meta_file(base_dir.c_str(), name.c_str());
+
+  for (vector<Index *>::iterator it = table->indexes_.begin(); it != table->indexes_.end(); ++it) {
+    Index *index = *it;
+    drop_index(table, index);
+  }
+  delete table;
+  ::remove(path.c_str());
+  ::remove((path + ".tmp").c_str());
+  string data_file = table_data_file(base_dir.c_str(), name.c_str());
+  ::remove(data_file.c_str());
+  return RC::SUCCESS;
+}
+
 RC Table::open(Db *db, const char *meta_file, const char *base_dir)
 {
   // 加载元数据文件
@@ -451,6 +468,13 @@ RC Table::create_index(Trx *trx, const FieldMeta *field_meta, const char *index_
   return rc;
 }
 
+RC Table::drop_index(Table *table, Index *idx)
+{
+  string index_file = table_index_file(table->base_dir_.c_str(), table->name(), idx->index_meta().name());
+  ::remove(index_file.c_str());
+  return RC::SUCCESS;
+}
+
 RC Table::delete_record(const RID &rid)
 {
   RC     rc = RC::SUCCESS;

src/observer/storage/table/table.h

@@ -54,6 +54,11 @@ class Table
   RC create(Db *db, int32_t table_id, const char *path, const char *name, const char *base_dir,
       span<const AttrInfoSqlNode> attributes, StorageFormat storage_format);
 
+  /*
+   * 删除一个表，会回收Table内存
+   */
+  static RC drop(Table *table);
+
   /**
    * 打开一个表
    * @param meta_file 保存表元数据的文件完整路径
@@ -85,6 +90,11 @@ class Table
   // TODO refactor
   RC create_index(Trx *trx, const FieldMeta *field_meta, const char *index_name);
 
+  /*
+   * 删除index,不会释放内存
+   */
+  static RC drop_index(Table *table, Index *idx);
+
   RC get_record_scanner(RecordFileScanner &scanner, Trx *trx, ReadWriteMode mode);
 
   RC get_chunk_scanner(ChunkFileScanner &scanner, Trx *trx, ReadWriteMode mode);