- Enable MYSQL tables to USE result instead of STORE result.

See the issue reported in MDEV-6142.
modified:
  storage/connect/myconn.cpp
  storage/connect/myconn.h
  storage/connect/tabmysql.cpp
  storage/connect/tabmysql.h

storage/connect/myconn.cpp

@@ -31,6 +31,10 @@
 /*                                                                      */
 /************************************************************************/
 #include "my_global.h"
+#if !defined(MYSQL_PREPARED_STATEMENTS)
+#include "my_sys.h"
+#include "mysqld_error.h"
+#endif   // !MYSQL_PREPARED_STATEMENTS
 #if defined(WIN32)
 //#include <windows.h>
 #else   // !WIN32
@@ -59,6 +63,59 @@ uint GetDefaultPort(void)
   return mysqld_port;
 } // end of GetDefaultPort
 
+#if !defined(MYSQL_PREPARED_STATEMENTS)
+/**************************************************************************
+  Alloc struct for use with unbuffered reads. Data is fetched by domand
+  when calling to mysql_fetch_row.
+  mysql_data_seek is a noop.
+
+  No other queries may be specified with the same MYSQL handle.
+  There shouldn't be much processing per row because mysql server shouldn't
+  have to wait for the client (and will not wait more than 30 sec/packet).
+  NOTE: copied from client.c cli_use_result
+**************************************************************************/
+static MYSQL_RES *connect_use_result(MYSQL *mysql)
+{
+  MYSQL_RES *result;
+  DBUG_ENTER("connect_use_result");
+
+  if (!mysql->fields)
+    DBUG_RETURN(NULL);
+
+  if (mysql->status != MYSQL_STATUS_GET_RESULT) {
+    my_message(ER_UNKNOWN_ERROR, "Command out of sync", MYF(0));
+    DBUG_RETURN(NULL);
+    } // endif status
+
+  if (!(result = (MYSQL_RES*) my_malloc(sizeof(*result) +
+				          sizeof(ulong) * mysql->field_count,
+				          MYF(MY_WME | MY_ZEROFILL))))
+    DBUG_RETURN(NULL);
+
+  result->lengths = (ulong*)(result+1);
+  result->methods = mysql->methods;
+
+  /* Ptrs: to one row */
+  if (!(result->row = (MYSQL_ROW)my_malloc(sizeof(result->row[0]) *
+                                (mysql->field_count+1), MYF(MY_WME)))) {
+    my_free(result);
+    DBUG_RETURN(NULL);
+    }  // endif row
+
+  result->fields =	mysql->fields;
+  result->field_alloc =	mysql->field_alloc;
+  result->field_count =	mysql->field_count;
+  result->current_field = 0;
+  result->handle =	mysql;
+  result->current_row =	0;
+  mysql->fields = 0;			/* fields is now in result */
+  clear_alloc_root(&mysql->field_alloc);
+  mysql->status = MYSQL_STATUS_USE_RESULT;
+  mysql->unbuffered_fetch_owner = &result->unbuffered_fetch_cancelled;
+  DBUG_RETURN(result);			/* Data is ready to be fetched */
+} // end of connect_use_result
+#endif   // !MYSQL_PREPARED_STATEMENTS
+
 /************************************************************************/
 /*  MyColumns: constructs the result blocks containing all columns      */
 /*  of a MySQL table or view.                                           */
@@ -339,6 +396,7 @@ MYSQLC::MYSQLC(void)
   m_Row = NULL;
   m_Fields = -1;
   N = 0;
+  m_Use = false;
   } // end of MYSQLC constructor
 
 /***********************************************************************/
@@ -600,7 +658,16 @@ int MYSQLC::ExecSQL(PGLOBAL g, const char *query, int *w)
     rc = RC_FX;
 //} else if (mysql_field_count(m_DB) > 0) {
   } else if (m_DB->field_count > 0) {
-    if (!(m_Res = mysql_store_result(m_DB))) {
+    if (m_Use)
+#if defined(MYSQL_PREPARED_STATEMENTS)
+      m_Res = mysql_use_result(m_DB);
+#else   // !MYSQL_PREPARED_STATEMENTS)
+      m_Res = connect_use_result(m_DB);
+#endif  // !MYSQL_PREPARED_STATEMENTS
+    else
+      m_Res = mysql_store_result(m_DB);
+
+    if (!m_Res) {
       char *msg = (char*)PlugSubAlloc(g, NULL, 512 + strlen(query));
 
       sprintf(msg, "mysql_store_result failed: %s", mysql_error(m_DB));
@@ -609,7 +676,7 @@ int MYSQLC::ExecSQL(PGLOBAL g, const char *query, int *w)
       rc = RC_FX;
     } else {
       m_Fields = mysql_num_fields(m_Res);
-      m_Rows = (int)mysql_num_rows(m_Res);
+      m_Rows = (!m_Use) ? (int)mysql_num_rows(m_Res) : 0;
     } // endif m_Res
 
   } else {

storage/connect/myconn.h

@@ -96,5 +96,6 @@ class DllItem MYSQLC {
   int         N;
   int         m_Fields;     // The number of result fields
   int         m_Afrw;       // The number of affected rows
+  bool        m_Use;        // Use or store result set
   }; // end of class MYSQLC
 

storage/connect/tabmysql.cpp

@@ -84,10 +84,11 @@ MYSQLDEF::MYSQLDEF(void)
   Username = NULL;
   Password = NULL;
   Portnumber = 0;
-  Isview = FALSE;
+  Isview = false;
-  Bind = FALSE;
+  Bind = false;
-  Delayed = FALSE;
+  Delayed = false;
-  Xsrc = FALSE;
+  Xsrc = false;
+  Huge = false;
   } // end of MYSQLDEF constructor
 
 /***********************************************************************/
@@ -329,7 +330,7 @@ bool MYSQLDEF::DefineAM(PGLOBAL g, LPCSTR am, int poff)
   } else {
     // MYSQL access from a PROXY table 
     Database = GetStringCatInfo(g, "Database", "*");
-    Isview = GetBoolCatInfo("View", FALSE);
+    Isview = GetBoolCatInfo("View", false);
 
     // We must get other connection parms from the calling table
     Remove_tshp(Cat);
@@ -363,7 +364,8 @@ bool MYSQLDEF::DefineAM(PGLOBAL g, LPCSTR am, int poff)
   // Specific for command executing tables
   Xsrc = GetBoolCatInfo("Execsrc", false);
   Mxr = GetIntCatInfo("Maxerr", 0);
-  return FALSE;
+  Huge = GetBoolCatInfo("Huge", false);
+  return false;
   } // end of DefineAM
 
 /***********************************************************************/
@@ -401,6 +403,7 @@ TDBMYSQL::TDBMYSQL(PMYDEF tdp) : TDBASE(tdp)
     Isview = tdp->Isview;
     Prep = tdp->Bind;
     Delayed = tdp->Delayed;
+    Myc.m_Use = tdp->Huge;
   } else {
     Host = NULL;
     Database = NULL;
@@ -412,15 +415,15 @@ TDBMYSQL::TDBMYSQL(PMYDEF tdp) : TDBASE(tdp)
     Qrystr = NULL;
     Quoted = 0;
     Port = 0;
-    Isview = FALSE;
+    Isview = false;
-    Prep = FALSE;
+    Prep = false;
-    Delayed = FALSE;
+    Delayed = false;
   } // endif tdp
 
   Bind = NULL;
   Query = NULL;
   Qbuf = NULL;
-  Fetched = FALSE;
+  Fetched = false;
   m_Rc = RC_FX;
   AftRows = 0;
   N = -1;
@@ -555,17 +558,17 @@ bool TDBMYSQL::MakeInsert(PGLOBAL g)
   char *colist, *valist = NULL;
   char *tk = "`";
   int   len = 0, qlen = 0;
-  bool  b = FALSE;
+  bool  b = false;
   PCOL  colp;
 
   if (Query)
-    return FALSE;        // already done
+    return false;        // already done
 
   for (colp = Columns; colp; colp = colp->GetNext())
     if (!colp->IsSpecial()) {
 //    if (colp->IsSpecial()) {
 //      strcpy(g->Message, MSG(NO_SPEC_COL));
-//      return TRUE;
+//      return true;
 //    } else {
       len += (strlen(colp->GetName()) + 4);
       ((PMYCOL)colp)->Rank = Nparm++;
@@ -581,7 +584,7 @@ bool TDBMYSQL::MakeInsert(PGLOBAL g)
 #else   // !MYSQL_PREPARED_STATEMENTS
     strcpy(g->Message, "Prepared statements not used (not supported)");
     PushWarning(g, this);
-    Prep = FALSE;
+    Prep = false;
 #endif  // !MYSQL_PREPARED_STATEMENTS 
     } // endif Prep
 
@@ -590,7 +593,7 @@ bool TDBMYSQL::MakeInsert(PGLOBAL g)
       strcat(colist, ", ");
       if (Prep) strcat(valist, ",");
     } else
-      b = TRUE;
+      b = true;
 
     strcat(strcat(strcat(colist, tk), colp->GetName()), tk);
 
@@ -628,7 +631,7 @@ bool TDBMYSQL::MakeInsert(PGLOBAL g)
     Qbuf = (char *)PlugSubAlloc(g, NULL, qlen);
     } // endelse Prep
 
-  return FALSE;
+  return false;
   } // end of MakeInsert
 
 /***********************************************************************/
@@ -906,9 +909,9 @@ bool TDBMYSQL::SetColumnRanks(PGLOBAL g)
   {
   for (PCOL colp = Columns; colp; colp = colp->GetNext())
     if (((PMYCOL)colp)->FindRank(g))
-      return TRUE;
+      return true;
 
-  return FALSE;
+  return false;
   } // end of SetColumnRanks
 
 /***********************************************************************/
@@ -1233,7 +1236,7 @@ bool MYSQLCOL::SetBuffer(PGLOBAL g, PVAL value, bool ok, bool check)
   {
   if (!(To_Val = value)) {
     sprintf(g->Message, MSG(VALUE_ERROR), Name);
-    return TRUE;
+    return true;
   } else if (Buf_Type == value->GetType()) {
     // Values are of the (good) column type
     if (Buf_Type == TYPE_DATE) {
@@ -1253,12 +1256,12 @@ bool MYSQLCOL::SetBuffer(PGLOBAL g, PVAL value, bool ok, bool check)
     if (check) {
       sprintf(g->Message, MSG(TYPE_VALUE_ERR), Name,
               GetTypeName(Buf_Type), GetTypeName(value->GetType()));
-      return TRUE;
+      return true;
       } // endif check
 
  newval:
     if (InitValue(g))         // Allocate the matching value block
-      return TRUE;
+      return true;
 
   } // endif's Value, Buf_Type
 
@@ -1269,7 +1272,7 @@ bool MYSQLCOL::SetBuffer(PGLOBAL g, PVAL value, bool ok, bool check)
 
   // Set the Column
   Status = (ok) ? BUF_EMPTY : BUF_NO;
-  return FALSE;
+  return false;
   } // end of SetBuffer
 
 /***********************************************************************/
@@ -1317,7 +1320,7 @@ void MYSQLCOL::ReadColumn(PGLOBAL g)
 
       longjmp(g->jumper[g->jump_level], 11);
     } else
-      tdbp->Fetched = TRUE;
+      tdbp->Fetched = true;
 
   if ((buf = ((PTDBMY)To_Tdb)->Myc.GetCharField(Rank))) {
     if (trace > 1)
@@ -1354,7 +1357,7 @@ void MYSQLCOL::WriteColumn(PGLOBAL g)
   /*  Do convert the column value if necessary.                        */
   /*********************************************************************/
   if (Value != To_Val)
-    Value->SetValue_pval(To_Val, FALSE);   // Convert the inserted value
+    Value->SetValue_pval(To_Val, false);   // Convert the inserted value
 
 #if defined(MYSQL_PREPARED_STATEMENTS)
   if (((PTDBMY)To_Tdb)->Prep) {

storage/connect/tabmysql.h

@@ -58,10 +58,11 @@ class MYSQLDEF : public TABDEF           {/* Logical table description */
   int     Portnumber;         /* MySQL port number (0 = default)       */
   int     Mxr;                /* Maxerr for an Exec table              */
   int     Quoted;             /* Identifier quoting level              */
-  bool    Isview;             /* TRUE if this table is a MySQL view    */
+  bool    Isview;             /* true if this table is a MySQL view    */
   bool    Bind;               /* Use prepared statement on insert      */
   bool    Delayed;            /* Delayed insert                        */
   bool    Xsrc;               /* Execution type                        */
+  bool    Huge;               /* True for big table                    */
   }; // end of MYSQLDEF
 
 /***********************************************************************/
@@ -84,7 +85,7 @@ class TDBMYSQL : public TDBASE {
   virtual int  GetRecpos(void) {return N;}
   virtual int  GetProgMax(PGLOBAL g);
   virtual void ResetDB(void) {N = 0;}
-  virtual int  RowNumber(PGLOBAL g, bool b = FALSE);
+  virtual int  RowNumber(PGLOBAL g, bool b = false);
   virtual bool IsView(void) {return Isview;}
   virtual PSZ  GetServer(void) {return Server;}
           void SetDatabase(LPCSTR db) {Database = (char*)db;}