checkpoint - working version of c3p0 connection pooling, and read-only database meta-data connections (per query hint)

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/actions/reporting/ExportAction.java

@@ -44,6 +44,7 @@ import com.kingsrook.qqq.backend.core.logging.QLogger;
 import com.kingsrook.qqq.backend.core.model.actions.reporting.ExportInput;
 import com.kingsrook.qqq.backend.core.model.actions.reporting.ExportOutput;
 import com.kingsrook.qqq.backend.core.model.actions.reporting.ReportFormat;
+import com.kingsrook.qqq.backend.core.model.actions.tables.QueryHint;
 import com.kingsrook.qqq.backend.core.model.actions.tables.count.CountInput;
 import com.kingsrook.qqq.backend.core.model.actions.tables.count.CountOutput;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QQueryFilter;
@@ -216,7 +217,8 @@ public class ExportAction
       }
       queryInput.getFilter().setLimit(exportInput.getLimit());
       queryInput.setShouldTranslatePossibleValues(true);
-      queryInput.withQueryHint(QueryInput.QueryHint.POTENTIALLY_LARGE_NUMBER_OF_RESULTS);
+      queryInput.withQueryHint(QueryHint.POTENTIALLY_LARGE_NUMBER_OF_RESULTS);
+      queryInput.withQueryHint(QueryHint.MAY_USE_READ_ONLY_BACKEND);
 
       /////////////////////////////////////////////////////////////////
       // tell this query that it needs to put its output into a pipe //

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/actions/reporting/GenerateReportAction.java

@@ -59,6 +59,7 @@ import com.kingsrook.qqq.backend.core.model.actions.reporting.ExportInput;
 import com.kingsrook.qqq.backend.core.model.actions.reporting.ReportFormat;
 import com.kingsrook.qqq.backend.core.model.actions.reporting.ReportInput;
 import com.kingsrook.qqq.backend.core.model.actions.reporting.ReportOutput;
+import com.kingsrook.qqq.backend.core.model.actions.tables.QueryHint;
 import com.kingsrook.qqq.backend.core.model.actions.tables.count.CountInput;
 import com.kingsrook.qqq.backend.core.model.actions.tables.count.CountOutput;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.JoinsContext;
@@ -417,7 +418,8 @@ public class GenerateReportAction extends AbstractQActionFunction<ReportInput, R
             queryInput.setTableName(dataSource.getSourceTable());
             queryInput.setFilter(queryFilter);
             queryInput.setQueryJoins(dataSource.getQueryJoins());
-            queryInput.withQueryHint(QueryInput.QueryHint.POTENTIALLY_LARGE_NUMBER_OF_RESULTS);
+            queryInput.withQueryHint(QueryHint.POTENTIALLY_LARGE_NUMBER_OF_RESULTS);
+            queryInput.withQueryHint(QueryHint.MAY_USE_READ_ONLY_BACKEND);
 
             queryInput.setShouldTranslatePossibleValues(true);
             queryInput.setFieldsToTranslatePossibleValues(setupFieldsToTranslatePossibleValues(reportInput, dataSource, new JoinsContext(reportInput.getInstance(), dataSource.getSourceTable(), dataSource.getQueryJoins(), queryInput.getFilter())));

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/actions/values/QPossibleValueTranslator.java

@@ -32,13 +32,12 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
-import com.kingsrook.qqq.backend.core.actions.QBackendTransaction;
 import com.kingsrook.qqq.backend.core.actions.customizers.QCodeLoader;
 import com.kingsrook.qqq.backend.core.actions.tables.QueryAction;
 import com.kingsrook.qqq.backend.core.context.QContext;
 import com.kingsrook.qqq.backend.core.exceptions.QValueException;
 import com.kingsrook.qqq.backend.core.logging.QLogger;
-import com.kingsrook.qqq.backend.core.model.actions.tables.insert.InsertInput;
+import com.kingsrook.qqq.backend.core.model.actions.tables.QueryHint;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QCriteriaOperator;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QFilterCriteria;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QQueryFilter;
@@ -78,45 +77,6 @@ public class QPossibleValueTranslator
 
    private int maxSizePerPvsCache = 50_000;
 
-   private Map<String, QBackendTransaction> transactionsPerTable = new HashMap<>();
-
-   // todo not commit - remove instance & session - use Context
-
-
-   boolean useTransactionsAsConnectionPool = false;
-
-
-
-   /*******************************************************************************
-    **
-    *******************************************************************************/
-   private QBackendTransaction getTransaction(String tableName)
-   {
-      /////////////////////////////////////////////////////////////
-      // mmm, this does cut down on connections used -           //
-      // especially seems helpful in big exports.                //
-      // but, let's just start using connection pools instead... //
-      /////////////////////////////////////////////////////////////
-      if(useTransactionsAsConnectionPool)
-      {
-         try
-         {
-            if(!transactionsPerTable.containsKey(tableName))
-            {
-               transactionsPerTable.put(tableName, QBackendTransaction.openFor(new InsertInput(tableName)));
-            }
-
-            return (transactionsPerTable.get(tableName));
-         }
-         catch(Exception e)
-         {
-            LOG.warn("Error opening transaction for table", logPair("tableName", tableName));
-         }
-      }
-
-      return null;
-   }
-
 
 
    /*******************************************************************************
@@ -601,7 +561,7 @@ public class QPossibleValueTranslator
             QueryInput queryInput = new QueryInput();
             queryInput.setTableName(tableName);
             queryInput.setFilter(new QQueryFilter().withCriteria(new QFilterCriteria(idField, QCriteriaOperator.IN, page)));
-            queryInput.setTransaction(getTransaction(tableName));
+            queryInput.hasQueryHint(QueryHint.MAY_USE_READ_ONLY_BACKEND);
 
             /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
             // when querying for possible values, we do want to generate their display values, which makes record labels, which are usually used as PVS labels //

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/actions/tables/QueryHint.java

@@ -0,0 +1,38 @@
+/*
+ * QQQ - Low-code Application Framework for Engineers.
+ * Copyright (C) 2021-2024.  Kingsrook, LLC
+ * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
+ * contact@kingsrook.com
+ * https://github.com/Kingsrook/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.kingsrook.qqq.backend.core.model.actions.tables;
+
+
+/*******************************************************************************
+ ** Information about the query that an application (or qqq service) may know and
+ ** want to tell the backend, that can help influence how the backend processes
+ ** query.
+ **
+ ** For example, a query with potentially a large result set, for MySQL backend,
+ ** we may want to configure the result set to stream results rather than do its
+ ** default in-memory thing.  See RDBMSQueryAction for usage.
+ *******************************************************************************/
+public enum QueryHint
+{
+   POTENTIALLY_LARGE_NUMBER_OF_RESULTS,
+   MAY_USE_READ_ONLY_BACKEND
+}

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/actions/tables/aggregate/AggregateInput.java

@@ -23,8 +23,10 @@ package com.kingsrook.qqq.backend.core.model.actions.tables.aggregate;
 
 
 import java.util.ArrayList;
+import java.util.EnumSet;
 import java.util.List;
 import com.kingsrook.qqq.backend.core.model.actions.AbstractTableActionInput;
+import com.kingsrook.qqq.backend.core.model.actions.tables.QueryHint;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QQueryFilter;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QueryJoin;
 
@@ -44,6 +46,8 @@ public class AggregateInput extends AbstractTableActionInput
 
    private List<QueryJoin> queryJoins = null;
 
+   private EnumSet<QueryHint> queryHints = EnumSet.noneOf(QueryHint.class);
+
 
 
    /*******************************************************************************
@@ -302,4 +306,78 @@ public class AggregateInput extends AbstractTableActionInput
       return (this);
    }
 
+
+
+   /*******************************************************************************
+    ** Getter for queryHints
+    *******************************************************************************/
+   public EnumSet<QueryHint> getQueryHints()
+   {
+      return (this.queryHints);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for queryHints
+    *******************************************************************************/
+   public void setQueryHints(EnumSet<QueryHint> queryHints)
+   {
+      this.queryHints = queryHints;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for queryHints
+    *******************************************************************************/
+   public AggregateInput withQueryHints(EnumSet<QueryHint> queryHints)
+   {
+      this.queryHints = queryHints;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for queryHints
+    *******************************************************************************/
+   public AggregateInput withQueryHint(QueryHint queryHint)
+   {
+      if(this.queryHints == null)
+      {
+         this.queryHints = EnumSet.noneOf(QueryHint.class);
+      }
+      this.queryHints.add(queryHint);
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for queryHints
+    *******************************************************************************/
+   public AggregateInput withoutQueryHint(QueryHint queryHint)
+   {
+      if(this.queryHints != null)
+      {
+         this.queryHints.remove(queryHint);
+      }
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** null-safely check if query hints map contains the specified hint
+    *******************************************************************************/
+   public boolean hasQueryHint(QueryHint queryHint)
+   {
+      if(this.queryHints == null)
+      {
+         return (false);
+      }
+
+      return (queryHints.contains(queryHint));
+   }
 }

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/actions/tables/count/CountInput.java

@@ -23,8 +23,10 @@ package com.kingsrook.qqq.backend.core.model.actions.tables.count;
 
 
 import java.util.ArrayList;
+import java.util.EnumSet;
 import java.util.List;
 import com.kingsrook.qqq.backend.core.model.actions.AbstractTableActionInput;
+import com.kingsrook.qqq.backend.core.model.actions.tables.QueryHint;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QQueryFilter;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QueryJoin;
 
@@ -42,6 +44,8 @@ public class CountInput extends AbstractTableActionInput
    private List<QueryJoin> queryJoins           = null;
    private Boolean         includeDistinctCount = false;
 
+   private EnumSet<QueryHint> queryHints = EnumSet.noneOf(QueryHint.class);
+
 
 
    /*******************************************************************************
@@ -207,4 +211,78 @@ public class CountInput extends AbstractTableActionInput
       return (this);
    }
 
+
+
+   /*******************************************************************************
+    ** Getter for queryHints
+    *******************************************************************************/
+   public EnumSet<QueryHint> getQueryHints()
+   {
+      return (this.queryHints);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for queryHints
+    *******************************************************************************/
+   public void setQueryHints(EnumSet<QueryHint> queryHints)
+   {
+      this.queryHints = queryHints;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for queryHints
+    *******************************************************************************/
+   public CountInput withQueryHints(EnumSet<QueryHint> queryHints)
+   {
+      this.queryHints = queryHints;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for queryHints
+    *******************************************************************************/
+   public CountInput withQueryHint(QueryHint queryHint)
+   {
+      if(this.queryHints == null)
+      {
+         this.queryHints = EnumSet.noneOf(QueryHint.class);
+      }
+      this.queryHints.add(queryHint);
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for queryHints
+    *******************************************************************************/
+   public CountInput withoutQueryHint(QueryHint queryHint)
+   {
+      if(this.queryHints != null)
+      {
+         this.queryHints.remove(queryHint);
+      }
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** null-safely check if query hints map contains the specified hint
+    *******************************************************************************/
+   public boolean hasQueryHint(QueryHint queryHint)
+   {
+      if(this.queryHints == null)
+      {
+         return (false);
+      }
+
+      return (queryHints.contains(queryHint));
+   }
 }

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/actions/tables/query/QueryInput.java

@@ -31,12 +31,16 @@ import java.util.Set;
 import com.kingsrook.qqq.backend.core.actions.QBackendTransaction;
 import com.kingsrook.qqq.backend.core.actions.reporting.RecordPipe;
 import com.kingsrook.qqq.backend.core.model.actions.AbstractTableActionInput;
+import com.kingsrook.qqq.backend.core.model.actions.tables.QueryHint;
 import com.kingsrook.qqq.backend.core.model.actions.tables.QueryOrGetInputInterface;
 
 
 /*******************************************************************************
  ** Input data for the Query action
  **
+ ** Todo - maybe make a class between AbstractTableActionInput and {QueryInput,
+ ** CountInput, and AggregateInput}, with common attributes for all of these
+ ** "read" operations (like, queryHints,
  *******************************************************************************/
 public class QueryInput extends AbstractTableActionInput implements QueryOrGetInputInterface, Cloneable
 {
@@ -74,22 +78,6 @@ public class QueryInput extends AbstractTableActionInput implements QueryOrGetIn
 
 
 
-   /*******************************************************************************
-    ** Information about the query that an application (or qqq service) may know and
-    ** want to tell the backend, that can help influence how the backend processes
-    ** query.
-    **
-    ** For example, a query with potentially a large result set, for MySQL backend,
-    ** we may want to configure the result set to stream results rather than do its
-    ** default in-memory thing.  See RDBMSQueryAction for usage.
-    *******************************************************************************/
-   public enum QueryHint
-   {
-      POTENTIALLY_LARGE_NUMBER_OF_RESULTS
-   }
-
-
-
    /*******************************************************************************
     **
     *******************************************************************************/
@@ -683,4 +671,19 @@ public class QueryInput extends AbstractTableActionInput implements QueryOrGetIn
       return (this);
    }
 
+
+
+   /*******************************************************************************
+    ** null-safely check if query hints map contains the specified hint
+    *******************************************************************************/
+   public boolean hasQueryHint(QueryHint queryHint)
+   {
+      if(this.queryHints == null)
+      {
+         return (false);
+      }
+
+      return (queryHints.contains(queryHint));
+   }
+
 }

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/processes/implementations/garbagecollector/GarbageCollectorExtractStep.java

@@ -25,6 +25,7 @@ package com.kingsrook.qqq.backend.core.processes.implementations.garbagecollecto
 import java.time.Instant;
 import com.kingsrook.qqq.backend.core.exceptions.QException;
 import com.kingsrook.qqq.backend.core.model.actions.processes.RunBackendStepInput;
+import com.kingsrook.qqq.backend.core.model.actions.tables.QueryHint;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QQueryFilter;
 import com.kingsrook.qqq.backend.core.model.actions.tables.query.QueryInput;
 import com.kingsrook.qqq.backend.core.processes.implementations.etl.streamedwithfrontend.ExtractViaQueryStep;
@@ -66,7 +67,7 @@ public class GarbageCollectorExtractStep extends ExtractViaQueryStep
    @Override
    protected void customizeInputPreQuery(QueryInput queryInput)
    {
-      queryInput.withQueryHint(QueryInput.QueryHint.POTENTIALLY_LARGE_NUMBER_OF_RESULTS);
+      queryInput.withQueryHint(QueryHint.POTENTIALLY_LARGE_NUMBER_OF_RESULTS);
    }
 
 }