Vers SQL: Refactoring: better init of vers_conditions

Unit-based history point (vers_history_point_t; Vers_history_point).

sql/sql_select.cc

@@ -677,53 +677,37 @@ bool vers_select_conds_t::init_from_sysvar(THD *thd)
 {
   vers_asof_timestamp_t &in= thd->variables.vers_asof_timestamp;
   type= (vers_system_time_t) in.type;
-  unit_start= VERS_TIMESTAMP;
+  start.unit= VERS_TIMESTAMP;
   from_query= false;
   if (type != SYSTEM_TIME_UNSPECIFIED && type != SYSTEM_TIME_ALL)
   {
     DBUG_ASSERT(type == SYSTEM_TIME_AS_OF);
-    start= new (thd->mem_root)
+    start.item= new (thd->mem_root)
         Item_datetime_literal(thd, &in.ltime, TIME_SECOND_PART_DIGITS);
-    if (!start)
+    if (!start.item)
       return true;
   }
   else
-    start= NULL;
-  end= NULL;
+    start.item= NULL;
+  end.empty();
   return false;
 }
 
 void vers_select_conds_t::print(String *str, enum_query_type query_type)
 {
-  const static LEX_CSTRING unit_type[]=
-  {
-    { STRING_WITH_LEN("") },
-    { STRING_WITH_LEN("TIMESTAMP ") },
-    { STRING_WITH_LEN("TRANSACTION ") }
-  };
   switch (type) {
   case SYSTEM_TIME_UNSPECIFIED:
     break;
   case SYSTEM_TIME_AS_OF:
-    str->append(STRING_WITH_LEN(" FOR SYSTEM_TIME AS OF "));
-    str->append(unit_type + unit_start);
-    start->print(str, query_type);
+    start.print(str, query_type, STRING_WITH_LEN(" FOR SYSTEM_TIME AS OF "));
     break;
   case SYSTEM_TIME_FROM_TO:
-    str->append(STRING_WITH_LEN(" FOR SYSTEM_TIME FROM "));
-    str->append(unit_type + unit_start);
-    start->print(str, query_type);
-    str->append(STRING_WITH_LEN(" TO "));
-    str->append(unit_type + unit_end);
-    end->print(str, query_type);
+    start.print(str, query_type, STRING_WITH_LEN(" FOR SYSTEM_TIME FROM "));
+    end.print(str, query_type, STRING_WITH_LEN(" TO "));
     break;
   case SYSTEM_TIME_BETWEEN:
-    str->append(STRING_WITH_LEN(" FOR SYSTEM_TIME BETWEEN "));
-    str->append(unit_type + unit_start);
-    start->print(str, query_type);
-    str->append(STRING_WITH_LEN(" AND "));
-    str->append(unit_type + unit_end);
-    end->print(str, query_type);
+    start.print(str, query_type, STRING_WITH_LEN(" FOR SYSTEM_TIME BETWEEN "));
+    end.print(str, query_type, STRING_WITH_LEN(" AND "));
     break;
   case SYSTEM_TIME_BEFORE:
     DBUG_ASSERT(0);
@@ -871,8 +855,8 @@ int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables, COND **where_expr
         vers_system_time_t/VERS_TRX_ID at stage of fix_fields()
         (this is large refactoring). */
       vers_conditions.resolve_units(timestamps_only);
-      if (timestamps_only && (vers_conditions.unit_start == VERS_TRX_ID ||
-        vers_conditions.unit_end == VERS_TRX_ID))
+      if (timestamps_only && (vers_conditions.start.unit == VERS_TRX_ID ||
+        vers_conditions.end.unit == VERS_TRX_ID))
       {
         my_error(ER_VERS_ENGINE_UNSUPPORTED, MYF(0), table->table_name.str);
         DBUG_RETURN(-1);
@@ -889,53 +873,8 @@ int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables, COND **where_expr
     {
       if (vers_conditions)
       {
-        if (vers_conditions.start)
-        {
-          if (!vers_conditions.unit_start)
-            vers_conditions.unit_start= t->s->versioned;
-          switch (vers_conditions.unit_start)
-          {
-          case VERS_TIMESTAMP:
-          {
-            vers_conditions.start= newx Item_datetime_from_unixtime_typecast(
-              thd, vers_conditions.start, 6);
-            break;
-          }
-          case VERS_TRX_ID:
-          {
-            vers_conditions.start= newx Item_longlong_typecast(
-              thd, vers_conditions.start);
-            break;
-          }
-          default:
-            DBUG_ASSERT(0);
-            break;
-          }
-        }
-
-        if (vers_conditions.end)
-        {
-          if (!vers_conditions.unit_end)
-            vers_conditions.unit_end= t->s->versioned;
-          switch (vers_conditions.unit_end)
-          {
-          case VERS_TIMESTAMP:
-          {
-            vers_conditions.end= newx Item_datetime_from_unixtime_typecast(
-              thd, vers_conditions.end, 6);
-            break;
-          }
-          case VERS_TRX_ID:
-          {
-            vers_conditions.end= newx Item_longlong_typecast(
-              thd, vers_conditions.end);
-            break;
-          }
-          default:
-            DBUG_ASSERT(0);
-            break;
-          }
-        }
+        vers_conditions.start.add_typecast(thd, t->s->versioned);
+        vers_conditions.end.add_typecast(thd, t->s->versioned);
       }
       switch (vers_conditions.type)
       {
@@ -957,26 +896,19 @@ int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables, COND **where_expr
         cond1= or_items(thd, cond1, newx Item_func_isnull(thd, row_end));
         break;
       case SYSTEM_TIME_AS_OF:
-        cond1= newx Item_func_le(thd, row_start,
-          vers_conditions.start);
-        cond2= newx Item_func_gt(thd, row_end,
-          vers_conditions.start);
+        cond1= newx Item_func_le(thd, row_start, vers_conditions.start.item);
+        cond2= newx Item_func_gt(thd, row_end, vers_conditions.start.item);
         break;
       case SYSTEM_TIME_FROM_TO:
-        cond1= newx Item_func_lt(thd, row_start,
-          vers_conditions.end);
-        cond2= newx Item_func_ge(thd, row_end,
-          vers_conditions.start);
+        cond1= newx Item_func_lt(thd, row_start, vers_conditions.end.item);
+        cond2= newx Item_func_ge(thd, row_end, vers_conditions.start.item);
         break;
       case SYSTEM_TIME_BETWEEN:
-        cond1= newx Item_func_le(thd, row_start,
-          vers_conditions.end);
-        cond2= newx Item_func_ge(thd, row_end,
-          vers_conditions.start);
+        cond1= newx Item_func_le(thd, row_start, vers_conditions.end.item);
+        cond2= newx Item_func_ge(thd, row_end, vers_conditions.start.item);
         break;
       case SYSTEM_TIME_BEFORE:
-        cond1= newx Item_func_lt(thd, row_end,
-          vers_conditions.start);
+        cond1= newx Item_func_lt(thd, row_end, vers_conditions.start.item);
         break;
       default:
         DBUG_ASSERT(0);
@@ -995,29 +927,29 @@ int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables, COND **where_expr
         cond1= newx Item_func_eq(thd, row_end, curr);
         break;
       case SYSTEM_TIME_AS_OF:
-        trx_id0= vers_conditions.unit_start == VERS_TIMESTAMP ?
-          newx Item_func_vtq_id(thd, vers_conditions.start, TR_table::FLD_TRX_ID) :
-          vers_conditions.start;
+        trx_id0= vers_conditions.start.unit == VERS_TIMESTAMP
+          ?  newx Item_func_vtq_id(thd, vers_conditions.start.item, TR_table::FLD_TRX_ID)
+          : vers_conditions.start.item;
         cond1= newx Item_func_vtq_trx_sees_eq(thd, trx_id0, row_start);
         cond2= newx Item_func_vtq_trx_sees(thd, row_end, trx_id0);
         break;
       case SYSTEM_TIME_FROM_TO:
       case SYSTEM_TIME_BETWEEN:
-        trx_id0= vers_conditions.unit_start == VERS_TIMESTAMP ?
-          newx Item_func_vtq_id(thd, vers_conditions.start, TR_table::FLD_TRX_ID, true) :
-          vers_conditions.start;
-        trx_id1= vers_conditions.unit_end == VERS_TIMESTAMP ?
-          newx Item_func_vtq_id(thd, vers_conditions.end, TR_table::FLD_TRX_ID, false) :
-          vers_conditions.end;
-        cond1= vers_conditions.type == SYSTEM_TIME_FROM_TO ?
-          newx Item_func_vtq_trx_sees(thd, trx_id1, row_start) :
-          newx Item_func_vtq_trx_sees_eq(thd, trx_id1, row_start);
+        trx_id0= vers_conditions.start.unit == VERS_TIMESTAMP
+          ? newx Item_func_vtq_id(thd, vers_conditions.start.item, TR_table::FLD_TRX_ID, true)
+          : vers_conditions.start.item;
+        trx_id1= vers_conditions.end.unit == VERS_TIMESTAMP
+          ? newx Item_func_vtq_id(thd, vers_conditions.end.item, TR_table::FLD_TRX_ID, false)
+          : vers_conditions.end.item;
+        cond1= vers_conditions.type == SYSTEM_TIME_FROM_TO
+          ? newx Item_func_vtq_trx_sees(thd, trx_id1, row_start)
+          : newx Item_func_vtq_trx_sees_eq(thd, trx_id1, row_start);
         cond2= newx Item_func_vtq_trx_sees_eq(thd, row_end, trx_id0);
         break;
       case SYSTEM_TIME_BEFORE:
-        trx_id0= vers_conditions.unit_start == VERS_TIMESTAMP ?
-          newx Item_func_vtq_id(thd, vers_conditions.start, TR_table::FLD_TRX_ID) :
-          vers_conditions.start;
+        trx_id0= vers_conditions.start.unit == VERS_TIMESTAMP
+          ? newx Item_func_vtq_id(thd, vers_conditions.start.item, TR_table::FLD_TRX_ID)
+          : vers_conditions.start.item;
         cond1= newx Item_func_lt(thd, row_end, trx_id0);
         break;
       default:

sql/sql_yacc.yy

@@ -752,27 +752,6 @@ bool LEX::set_bincmp(CHARSET_INFO *cs, bool bin)
   } while(0)
 
 
-void vers_select_conds_t::init(vers_system_time_t t, vers_sys_type_t u_start,
-                               Item *s, vers_sys_type_t u_end, Item *e)
-{
-  type= t;
-  unit_start= u_start;
-  unit_end= u_end;
-  start= fix_dec(s);
-  end= fix_dec(e);
-  used= from_query= false;
-}
-
-Item *vers_select_conds_t::fix_dec(Item *item)
-{
-  if (item && item->decimals == 0 && item->type() == Item::FUNC_ITEM &&
-      ((Item_func*)item)->functype() == Item_func::NOW_FUNC)
-    item->decimals= 6;
-
-  return item;
-}
-
-
 Virtual_column_info *add_virtual_expression(THD *thd, Item *expr)
 {
   Virtual_column_info *v= new (thd->mem_root) Virtual_column_info();
@@ -813,6 +792,7 @@ Virtual_column_info *add_virtual_expression(THD *thd, Item *expr)
     LEX_CSTRING name;
     uint offset;
   } sp_cursor_name_and_offset;
+  vers_history_point_t vers_history_point;
 
   /* pointers */
   Create_field *create_field;
@@ -2046,7 +2026,8 @@ END_OF_INPUT
 
 %type <lex_str_list> opt_with_column_list
 
-%type <vers_range_unit> opt_trans_or_timestamp
+%type <vers_range_unit> opt_history_unit
+%type <vers_history_point> history_point
 %type <vers_column_versioning> with_or_without_system
 %%
 
@@ -9203,18 +9184,25 @@ select_options:
           }
         ;
 
-opt_trans_or_timestamp:
-          /* empty */
+opt_history_unit:
+          /* empty*/
           {
-            $$ = VERS_UNDEFINED;
+            $$= VERS_UNDEFINED;
           }
         | TRANSACTION_SYM
           {
-            $$ = VERS_TRX_ID;
+            $$= VERS_TRX_ID;
           }
         | TIMESTAMP
           {
-            $$ = VERS_TIMESTAMP;
+            $$= VERS_TIMESTAMP;
+          }
+        ;
+
+history_point:
+          opt_history_unit simple_expr
+          {
+            $$= Vers_history_point($1, $2);
           }
         ;
 
@@ -9230,23 +9218,23 @@ opt_for_system_time_clause:
         ;
 
 system_time_expr:
-          AS OF_SYM opt_trans_or_timestamp simple_expr
+          AS OF_SYM history_point
           {
-            Lex->vers_conditions.init(SYSTEM_TIME_AS_OF, $3, $4);
+            Lex->vers_conditions.init(SYSTEM_TIME_AS_OF, $3);
           }
         | ALL
           {
             Lex->vers_conditions.init(SYSTEM_TIME_ALL);
           }
-        | FROM opt_trans_or_timestamp simple_expr
-          TO_SYM opt_trans_or_timestamp simple_expr
+        | FROM history_point
+          TO_SYM history_point
           {
-            Lex->vers_conditions.init(SYSTEM_TIME_FROM_TO, $2, $3, $5, $6);
+            Lex->vers_conditions.init(SYSTEM_TIME_FROM_TO, $2, $4);
           }
-        | BETWEEN_SYM opt_trans_or_timestamp simple_expr
-          AND_SYM opt_trans_or_timestamp simple_expr
+        | BETWEEN_SYM history_point
+          AND_SYM history_point
           {
-            Lex->vers_conditions.init(SYSTEM_TIME_BETWEEN, $2, $3, $5, $6);
+            Lex->vers_conditions.init(SYSTEM_TIME_BETWEEN, $2, $4);
           }
         ;
 
@@ -13447,9 +13435,9 @@ opt_delete_system_time:
           {
             Lex->vers_conditions.init(SYSTEM_TIME_ALL);
           }
-          | BEFORE_SYM SYSTEM_TIME_SYM opt_trans_or_timestamp simple_expr
+          | BEFORE_SYM SYSTEM_TIME_SYM history_point
           {
-            Lex->vers_conditions.init(SYSTEM_TIME_BEFORE, $3, $4);
+            Lex->vers_conditions.init(SYSTEM_TIME_BEFORE, $3);
           }
           ;
 

sql/table.cc

@@ -8920,27 +8920,67 @@ bool TR_table::check(bool error)
 void vers_select_conds_t::resolve_units(bool timestamps_only)
 {
   DBUG_ASSERT(type != SYSTEM_TIME_UNSPECIFIED);
-  DBUG_ASSERT(start);
-  if (unit_start == VERS_UNDEFINED)
+  DBUG_ASSERT(start.item);
+  start.resolve_unit(timestamps_only);
+  end.resolve_unit(timestamps_only);
+}
+
+void Vers_history_point::resolve_unit(bool timestamps_only)
+{
+  if (item && unit == VERS_UNDEFINED)
   {
-    if (start->type() == Item::FIELD_ITEM)
-      unit_start= VERS_TIMESTAMP;
+    if (item->type() == Item::FIELD_ITEM || timestamps_only)
+      unit= VERS_TIMESTAMP;
+    else if (item->result_type() == INT_RESULT ||
+             item->result_type() == REAL_RESULT)
+      unit= VERS_TRX_ID;
     else
-      unit_start= (!timestamps_only && (start->result_type() == INT_RESULT ||
-        start->result_type() == REAL_RESULT)) ?
-          VERS_TRX_ID : VERS_TIMESTAMP;
+      unit= VERS_TIMESTAMP;
   }
-  if (end && unit_end == VERS_UNDEFINED)
+}
+
+void Vers_history_point::fix_item()
+{
+  if (item && item->decimals == 0 && item->type() == Item::FUNC_ITEM &&
+      ((Item_func*)item)->functype() == Item_func::NOW_FUNC)
+    item->decimals= 6;
+}
+
+void Vers_history_point::add_typecast(THD *thd, enum vers_sys_type_t defunit)
+{
+  if (item)
   {
-    if (start->type() == Item::FIELD_ITEM)
-      unit_start= VERS_TIMESTAMP;
-    else
-      unit_end= (!timestamps_only && (end->result_type() == INT_RESULT ||
-        end->result_type() == REAL_RESULT)) ?
-          VERS_TRX_ID : VERS_TIMESTAMP;
+    if (!unit)
+      unit= defunit;
+    switch (unit)
+    {
+    case VERS_TIMESTAMP:
+      item= new (thd->mem_root) Item_datetime_from_unixtime_typecast(
+                                    thd, item, MAX_DATETIME_PRECISION);
+      break;
+    case VERS_TRX_ID:
+      item= new (thd->mem_root) Item_longlong_typecast(thd, item);
+      break;
+    default:
+      DBUG_ASSERT(0);
+      break;
+    }
   }
 }
 
+void Vers_history_point::print(String *str, enum_query_type query_type,
+                               const char *prefix, size_t plen)
+{
+  const static LEX_CSTRING unit_type[]=
+  {
+    { STRING_WITH_LEN("") },
+    { STRING_WITH_LEN("TIMESTAMP ") },
+    { STRING_WITH_LEN("TRANSACTION ") }
+  };
+  str->append(prefix, plen);
+  str->append(unit_type + unit);
+  item->print(str, query_type);
+}
 
 Field *TABLE::find_field_by_name(LEX_CSTRING *str) const
 {

sql/table.h

@@ -1841,64 +1841,62 @@ class SJ_MATERIALIZATION_INFO;
 class Index_hint;
 class Item_in_subselect;
 
+/* trivial class, for %union in sql_yacc.yy */
+struct vers_history_point_t
+{
+  vers_sys_type_t unit;
+  Item *item;
+};
 
-/*
-  Table reference in the FROM clause.
-
-  These table references can be of several types that correspond to
-  different SQL elements. Below we list all types of TABLE_LISTs with
-  the necessary conditions to determine when a TABLE_LIST instance
-  belongs to a certain type.
+class Vers_history_point : public vers_history_point_t
+{
+  void fix_item();
 
-  1) table (TABLE_LIST::view == NULL)
-     - base table
-       (TABLE_LIST::derived == NULL)
-     - FROM-clause subquery - TABLE_LIST::table is a temp table
-       (TABLE_LIST::derived != NULL)
-     - information schema table
-       (TABLE_LIST::schema_table != NULL)
-       NOTICE: for schema tables TABLE_LIST::field_translation may be != NULL
-  2) view (TABLE_LIST::view != NULL)
-     - merge    (TABLE_LIST::effective_algorithm == VIEW_ALGORITHM_MERGE)
-           also (TABLE_LIST::field_translation != NULL)
-     - tmptable (TABLE_LIST::effective_algorithm == VIEW_ALGORITHM_TMPTABLE)
-           also (TABLE_LIST::field_translation == NULL)
-  2.5) TODO: Add derived tables description here
-  3) nested table reference (TABLE_LIST::nested_join != NULL)
-     - table sequence - e.g. (t1, t2, t3)
-       TODO: how to distinguish from a JOIN?
-     - general JOIN
-       TODO: how to distinguish from a table sequence?
-     - NATURAL JOIN
-       (TABLE_LIST::natural_join != NULL)
-       - JOIN ... USING
-         (TABLE_LIST::join_using_fields != NULL)
-     - semi-join nest (sj_on_expr!= NULL && sj_subq_pred!=NULL)
-  4) jtbm semi-join (jtbm_subselect != NULL)
-*/
+public:
+  Vers_history_point() { empty(); }
+  Vers_history_point(vers_sys_type_t unit_arg, Item *item_arg)
+  {
+    unit= unit_arg;
+    item= item_arg;
+    fix_item();
+  }
+  Vers_history_point(vers_history_point_t p)
+  {
+    unit= p.unit;
+    item= p.item;
+    fix_item();
+  }
+  void empty() { unit= VERS_UNDEFINED; item= NULL; }
+  void print(String *str, enum_query_type, const char *prefix, size_t plen);
+  void resolve_unit(bool timestamps_only);
+  void add_typecast(THD *thd, enum vers_sys_type_t defunit);
+};
 
-/** last_leaf_for_name_resolutioning support. */
 struct vers_select_conds_t
 {
   vers_system_time_t type;
-  vers_sys_type_t unit_start, unit_end;
   bool from_query:1;
   bool used:1;
-  Item *start, *end;
+  Vers_history_point start;
+  Vers_history_point end;
 
   void empty()
   {
     type= SYSTEM_TIME_UNSPECIFIED;
-    unit_start= unit_end= VERS_UNDEFINED;
     used= from_query= false;
-    start= end= NULL;
+    start.empty();
+    end.empty();
   }
 
-  Item *fix_dec(Item *item);
-
-  void init(vers_system_time_t t, vers_sys_type_t u_start= VERS_UNDEFINED,
-            Item * s= NULL, vers_sys_type_t u_end= VERS_UNDEFINED,
-            Item * e= NULL);
+  void init(vers_system_time_t _type,
+            Vers_history_point _start= Vers_history_point(),
+            Vers_history_point _end= Vers_history_point())
+  {
+    type= _type;
+    used= from_query= false;
+    start= _start;
+    end= _end;
+  }
 
   void print(String *str, enum_query_type query_type);
 
@@ -1923,6 +1921,43 @@ struct vers_select_conds_t
   }
 };
 
+/*
+  Table reference in the FROM clause.
+
+  These table references can be of several types that correspond to
+  different SQL elements. Below we list all types of TABLE_LISTs with
+  the necessary conditions to determine when a TABLE_LIST instance
+  belongs to a certain type.
+
+  1) table (TABLE_LIST::view == NULL)
+     - base table
+       (TABLE_LIST::derived == NULL)
+     - FROM-clause subquery - TABLE_LIST::table is a temp table
+       (TABLE_LIST::derived != NULL)
+     - information schema table
+       (TABLE_LIST::schema_table != NULL)
+       NOTICE: for schema tables TABLE_LIST::field_translation may be != NULL
+  2) view (TABLE_LIST::view != NULL)
+     - merge    (TABLE_LIST::effective_algorithm == VIEW_ALGORITHM_MERGE)
+           also (TABLE_LIST::field_translation != NULL)
+     - tmptable (TABLE_LIST::effective_algorithm == VIEW_ALGORITHM_TMPTABLE)
+           also (TABLE_LIST::field_translation == NULL)
+  2.5) TODO: Add derived tables description here
+  3) nested table reference (TABLE_LIST::nested_join != NULL)
+     - table sequence - e.g. (t1, t2, t3)
+       TODO: how to distinguish from a JOIN?
+     - general JOIN
+       TODO: how to distinguish from a table sequence?
+     - NATURAL JOIN
+       (TABLE_LIST::natural_join != NULL)
+       - JOIN ... USING
+         (TABLE_LIST::join_using_fields != NULL)
+     - semi-join nest (sj_on_expr!= NULL && sj_subq_pred!=NULL)
+  4) jtbm semi-join (jtbm_subselect != NULL)
+*/
+
+/** last_leaf_for_name_resolutioning support. */
+
 struct LEX;
 class Index_hint;
 struct TABLE_LIST