Sev mysql, policy when selecting values with deadband changed

sev/lib/sev/src/sev_dbms.cpp

@@ -1482,6 +1482,7 @@ int sev_dbms::get_values( pwr_tStatus *sts, pwr_tOid oid, pwr_tMask options, flo
   char orderby_part[80];
   char jumpstr[40];
   char where_part[200];
+  int rows;
 
   if ( starttime && starttime->tv_sec == 0 && starttime->tv_nsec == 0)
     starttime = 0;
@@ -1620,7 +1621,7 @@ int sev_dbms::get_values( pwr_tStatus *sts, pwr_tOid oid, pwr_tMask options, flo
     strcpy( column_part, "time,value");
 
   if ( options & pwr_mSevOptionsMask_UseDeadBand)
-    strcpy( jumpstr, "or jump = 1");
+    strcpy( jumpstr, ""); // "or jump = 1" removed
   else
     strcpy( jumpstr, "");
 
@@ -1634,6 +1635,7 @@ int sev_dbms::get_values( pwr_tStatus *sts, pwr_tOid oid, pwr_tMask options, flo
       strcpy( orderby_part, "time");
   }
 
+  for ( int k = 0; k < 2; k++) {
     // 'where' part
     if ( options & pwr_mSevOptionsMask_ReadOptimized) {
       if ( starttime && endtime) {
@@ -1711,8 +1713,8 @@ int sev_dbms::get_values( pwr_tStatus *sts, pwr_tOid oid, pwr_tMask options, flo
 	strcpy( where_part, "");
     }  
     
-  sprintf( query, "select %s from %s %s order by %s",
-           column_part, item.tablename, where_part, orderby_part);
+    sprintf( query, "select %s from %s %s order by %s limit %d",
+	     column_part, item.tablename, where_part, orderby_part, maxsize*2);
     
     rc = mysql_query( m_env->con(), query);
     if (rc) {
@@ -1729,9 +1731,23 @@ int sev_dbms::get_values( pwr_tStatus *sts, pwr_tOid oid, pwr_tMask options, flo
       *sts = SEV__DBERROR;
       return 0;
     }
-  int rows = mysql_num_rows( result);
-  int bufrows = rows;
+    rows = mysql_num_rows( result);
 
+    if ( k == 0 && 
+	 options & pwr_mSevOptionsMask_UseDeadBand && 
+	 rows < maxsize / 3 && 
+	 rows != 0 &&
+	 div != 1) {
+      // Try another read with smaller div
+      printf( "Retry: %d old dev: %d, new div %d\n", rows, div, div * rows / maxsize + 1);
+      if ( div == div * rows / maxsize + 1)
+	break;
+      div = div * rows / maxsize + 1;
+      mysql_free_result( result);
+    }
+    else break;
+  }
+  int bufrows = rows;
 
   if ( options & pwr_mSevOptionsMask_ReadOptimized) {
 
@@ -4062,10 +4078,10 @@ void sev_dbms::add_cache( int item_idx)
   case pwr_eType_Int32:
     if ( m_items[item_idx].options & pwr_mSevOptionsMask_DeadBandMeanValue)
       m_items[item_idx].cache = new sev_valuecache_double( sev_eCvType_Mean, m_items[item_idx].deadband, 
-							   m_items[item_idx].scantime);
+							   m_items[item_idx].scantime/2);
     else
       m_items[item_idx].cache = new sev_valuecache_double( sev_eCvType_Point, m_items[item_idx].deadband, 
-							   m_items[item_idx].scantime);
+							   m_items[item_idx].scantime/2);
     m_items[item_idx].cache->set_write_cb( write_db_cb, this, item_idx);
     break;
   case pwr_eType_Boolean: