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diff --git a/storage/perfschema/table_uvar_by_thread.h b/storage/perfschema/table_uvar_by_thread.h
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+/* Copyright (c) 2013, 2022, Oracle and/or its affiliates.
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License, version 2.0,
+  as published by the Free Software Foundation.
+
+  This program is also distributed with certain software (including
+  but not limited to OpenSSL) that is licensed under separate terms,
+  as designated in a particular file or component or in included license
+  documentation.  The authors of MySQL hereby grant you an additional
+  permission to link the program and your derivative works with the
+  separately licensed software that they have included with MySQL.
+
+  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
+  GNU General Public License, version 2.0, for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+
+#ifndef TABLE_UVAR_BY_THREAD_H
+#define TABLE_UVAR_BY_THREAD_H
+
+/**
+  @file storage/perfschema/table_uvar_by_thread.h
+  Table USER_VARIABLES_BY_THREAD (declarations).
+*/
+
+#include "pfs_column_types.h"
+#include "pfs_engine_table.h"
+#include "pfs_instr_class.h"
+#include "pfs_instr.h"
+#include "table_helper.h"
+
+/**
+  @addtogroup Performance_schema_tables
+  @{
+*/
+
+struct User_variable
+{
+public:
+  User_variable()
+  {}
+
+  User_variable(const User_variable& uv)
+    : m_name(uv.m_name), m_value(uv.m_value)
+  {}
+
+  ~User_variable()
+  {}
+
+  PFS_variable_name_row m_name;
+  PFS_user_variable_value_row m_value;
+};
+
+class User_variables
+{
+  typedef Dynamic_array<User_variable> User_variable_array;
+
+public:
+  User_variables()
+    : m_pfs(NULL), m_thread_internal_id(0), m_array(PSI_INSTRUMENT_MEM)
+  {
+  }
+
+  void reset()
+  {
+    m_pfs= NULL;
+    m_thread_internal_id= 0;
+    for (uint i=0; i < m_array.elements(); i++)
+      m_array.at(i).~User_variable();
+    m_array.clear();
+  }
+
+  void materialize(PFS_thread *pfs, THD *thd);
+
+  bool is_materialized(PFS_thread *pfs)
+  {
+    assert(pfs != NULL);
+    if (m_pfs != pfs)
+      return false;
+    if (m_thread_internal_id != pfs->m_thread_internal_id)
+      return false;
+    return true;
+  }
+
+  const User_variable *get(uint index) const
+  {
+    if (index >= m_array.elements())
+      return NULL;
+
+    const User_variable *p= & m_array.at(index);
+    return p;
+  }
+
+private:
+  PFS_thread *m_pfs;
+  ulonglong m_thread_internal_id;
+  User_variable_array m_array;
+};
+
+/**
+  A row of table
+  PERFORMANCE_SCHEMA.USER_VARIABLES_BY_THREAD.
+*/
+struct row_uvar_by_thread
+{
+  /** Column THREAD_ID. */
+  ulonglong m_thread_internal_id;
+  /** Column VARIABLE_NAME. */
+  const PFS_variable_name_row *m_variable_name;
+  /** Column VARIABLE_VALUE. */
+  const PFS_user_variable_value_row *m_variable_value;
+};
+
+/**
+  Position of a cursor on
+  PERFORMANCE_SCHEMA.USER_VARIABLES_BY_THREAD.
+  Index 1 on thread (0 based)
+  Index 2 on user variable (0 based)
+*/
+struct pos_uvar_by_thread
+: public PFS_double_index
+{
+  pos_uvar_by_thread()
+    : PFS_double_index(0, 0)
+  {}
+
+  inline void reset(void)
+  {
+    m_index_1= 0;
+    m_index_2= 0;
+  }
+
+  inline void next_thread(void)
+  {
+    m_index_1++;
+    m_index_2= 0;
+  }
+};
+
+/** Table PERFORMANCE_SCHEMA.USER_VARIABLES_BY_THREAD. */
+class table_uvar_by_thread : public PFS_engine_table
+{
+  typedef pos_uvar_by_thread pos_t;
+
+public:
+  static PFS_engine_table_share_state m_share_state;
+  /** Table share */
+  static PFS_engine_table_share m_share;
+  static PFS_engine_table* create();
+  static ha_rows get_row_count();
+
+  virtual int rnd_next();
+  virtual int rnd_pos(const void *pos);
+  virtual void reset_position(void);
+
+protected:
+  virtual int read_row_values(TABLE *table,
+                              unsigned char *buf,
+                              Field **fields,
+                              bool read_all);
+
+  table_uvar_by_thread();
+
+public:
+  ~table_uvar_by_thread()
+  { m_THD_cache.reset(); }
+
+protected:
+  int materialize(PFS_thread *thread);
+  void make_row(PFS_thread *thread, const User_variable *uvar);
+
+private:
+  /** Table share lock. */
+  static THR_LOCK m_table_lock;
+  /** Fields definition. */
+  static TABLE_FIELD_DEF m_field_def;
+
+  /** Current THD user variables. */
+  User_variables m_THD_cache;
+  /** Current row. */
+  row_uvar_by_thread m_row;
+  /** True is the current row exists. */
+  bool m_row_exists;
+  /** Current position. */
+  pos_t m_pos;
+  /** Next position. */
+  pos_t m_next_pos;
+};
+
+/** @} */
+#endif