New system property h2.analyzeAuto.

h2/src/main/org/h2/command/ddl/Analyze.java

@@ -7,12 +7,13 @@
 package org.h2.command.ddl;
 
 import org.h2.command.Prepared;
+import org.h2.constant.SysProperties;
 import org.h2.engine.Database;
 import org.h2.engine.Session;
 import org.h2.result.ResultInterface;
 import org.h2.table.Column;
-import org.h2.table.Table;
 import org.h2.table.RegularTable;
+import org.h2.table.Table;
 import org.h2.util.StatementBuilder;
 
 /**
@@ -23,9 +24,8 @@ public class Analyze extends DefineCommand {
 
     /**
      * The sample size.
-     * The default value is also in the documentation.
      */
-    private int sampleRows = 10000;
+    private int sampleRows = SysProperties.ANALYZE_SAMPLE;
 
     public Analyze(Session session) {
         super(session);
@@ -33,36 +33,62 @@ public class Analyze extends DefineCommand {
 
     public int update() {
         session.commit(true);
-        Database db = session.getDatabase();
         session.getUser().checkAdmin();
+        Database db = session.getDatabase();
         // TODO do we need to lock the table?
         for (Table table : db.getAllTablesAndViews(false)) {
-            if (!(table instanceof RegularTable)) {
-                continue;
-            }
-            StatementBuilder buff = new StatementBuilder("SELECT ");
-            Column[] columns = table.getColumns();
-            for (Column col : columns) {
-                buff.appendExceptFirst(", ");
-                buff.append("SELECTIVITY(").append(col.getSQL()).append(')');
-            }
-            buff.append(" FROM ").append(table.getSQL());
-            if (sampleRows > 0) {
-                buff.append(" LIMIT 1 SAMPLE_SIZE ").append(sampleRows);
-            }
-            String sql = buff.toString();
-            Prepared command = session.prepare(sql);
-            ResultInterface result = command.query(0);
-            result.next();
-            for (int j = 0; j < columns.length; j++) {
-                int selectivity = result.currentRow()[j].getInt();
-                columns[j].setSelectivity(selectivity);
-            }
-            db.update(session, table);
+            analyzeTable(session, table, sampleRows, true);
         }
         return 0;
     }
 
+    /**
+     * Analyze this table.
+     *
+     * @param session the session
+     * @param table the table
+     * @param sample the number of sample rows
+     * @param manual whether the command was called by the user
+     */
+    public static void analyzeTable(Session session, Table table, int sample, boolean manual) {
+        if (!(table instanceof RegularTable) || table.isHidden() || session == null) {
+            return;
+        }
+        if (session.getDatabase().isSysTableLocked()) {
+            return;
+        }
+        if (table.isTemporary() && !table.isGlobalTemporary()
+                && session.findLocalTempTable(table.getName()) == null) {
+            return;
+        }
+        if (!manual && table.hasSelectTrigger()) {
+            return;
+        }
+        if (table.isLockedExclusively() && !table.isLockedExclusivelyBy(session)) {
+            return;
+        }
+        Database db = session.getDatabase();
+        StatementBuilder buff = new StatementBuilder("SELECT ");
+        Column[] columns = table.getColumns();
+        for (Column col : columns) {
+            buff.appendExceptFirst(", ");
+            buff.append("SELECTIVITY(").append(col.getSQL()).append(')');
+        }
+        buff.append(" FROM ").append(table.getSQL());
+        if (sample > 0) {
+            buff.append(" LIMIT 1 SAMPLE_SIZE ").append(sample);
+        }
+        String sql = buff.toString();
+        Prepared command = session.prepare(sql);
+        ResultInterface result = command.query(0);
+        result.next();
+        for (int j = 0; j < columns.length; j++) {
+            int selectivity = result.currentRow()[j].getInt();
+            columns[j].setSelectivity(selectivity);
+        }
+        db.update(session, table);
+    }
+
     public void setTop(int top) {
         this.sampleRows = top;
     }

h2/src/main/org/h2/constant/SysProperties.java

@@ -72,6 +72,23 @@ public class SysProperties {
      */
     public static final String USER_HOME = getStringSetting("user.home", "");
 
+    /**
+     * System property <code>h2.analyzeSample</code> (default: 10000).<br />
+     * The default sample size when analyzing a table.
+     */
+    public static final int ANALYZE_SAMPLE = getIntSetting("h2.analyzeSample", 10000);
+
+    /**
+     * System property <code>h2.analyzeSample</code> (default: 0).<br />
+     * After changing this many rows, ANALYZE is automatically run for a table.
+     * Automatically running ANALYZE is disabled if set to 0. If set to 1000,
+     * then ANALYZE will run against each user table after about 1000 changes to
+     * that table. The time between running ANALYZE doubles each time since
+     * starting the database. It is not run on local temporary tables, and
+     * tables that have a trigger on SELECT.
+     */
+    public static final int ANALYZE_AUTO = getIntSetting("h2.analyzeAuto", 0);
+
     /**
      * System property <code>h2.aliasColumnName</code> (default: false).<br />
      * When enabled, aliased columns (as in SELECT ID AS I FROM TEST) return the

h2/src/main/org/h2/engine/Database.java

@@ -562,6 +562,7 @@ public class Database implements DataHandler {
         data.persistData = persistent;
         data.persistIndexes = persistent;
         data.create = create;
+        data.isHidden = true;
         data.session = systemSession;
         meta = mainSchema.createTable(data);
         IndexColumn[] pkCols = IndexColumn.wrap(new Column[] { columnId });

h2/src/main/org/h2/schema/TriggerObject.java

@@ -374,4 +374,13 @@ public class TriggerObject extends SchemaObjectBase {
         }
     }
 
+    /**
+     * Check whether this is a select trigger.
+     *
+     * @return true if it is
+     */
+    public boolean isSelectTrigger() {
+        return (typeMask & Trigger.SELECT) != 0;
+    }
+
 }

h2/src/main/org/h2/table/RegularTable.java

@@ -12,6 +12,7 @@ import java.util.Comparator;
 import java.util.HashSet;
 import java.util.Set;
 import org.h2.api.DatabaseEventListener;
+import org.h2.command.ddl.Analyze;
 import org.h2.command.ddl.CreateTableData;
 import org.h2.constant.ErrorCode;
 import org.h2.constant.SysProperties;
@@ -57,6 +58,8 @@ public class RegularTable extends TableBase {
     private long lastModificationId;
     private boolean containsLargeObject;
     private PageDataIndex mainIndex;
+    private int changesSinceAnalyze;
+    private int nextAnalyze = SysProperties.ANALYZE_AUTO;
 
     /**
      * True if one thread ever was waiting to lock this table. This is to avoid
@@ -130,6 +133,7 @@ public class RegularTable extends TableBase {
             }
             throw DbException.convert(e);
         }
+        analyzeIfRequired(session);
     }
 
     private void checkRowCount(Session session, Index index, int offset) {
@@ -344,6 +348,7 @@ public class RegularTable extends TableBase {
             }
             throw DbException.convert(e);
         }
+        analyzeIfRequired(session);
     }
 
     public void truncate(Session session) {
@@ -353,6 +358,20 @@ public class RegularTable extends TableBase {
             index.truncate(session);
         }
         rowCount = 0;
+        changesSinceAnalyze = 0;
+    }
+
+    private void analyzeIfRequired(Session session) {
+        if (nextAnalyze == 0 || nextAnalyze > changesSinceAnalyze++) {
+            return;
+        }
+        changesSinceAnalyze = 0;
+        int n = 2 * nextAnalyze;
+        if (n > 0) {
+            nextAnalyze = n;
+        }
+        int rows = SysProperties.ANALYZE_SAMPLE;
+        Analyze.analyzeTable(session, this, rows, false);
     }
 
     public boolean isLockedExclusivelyBy(Session session) {

h2/src/main/org/h2/table/Table.java

@@ -741,6 +741,22 @@ public abstract class Table extends SchemaObjectBase {
         }
     }
 
+    /**
+     * Check whether this table has a select trigger.
+     *
+     * @return true if it has
+     */
+    public boolean hasSelectTrigger() {
+        if (triggers != null) {
+            for (TriggerObject trigger : triggers) {
+                if (trigger.isSelectTrigger()) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
     /**
      * Check if row based triggers or constraints are defined.
      * In this case the fire after and before row methods need to be called.