Adding JMCR-Stable version

[Benchmarks_CSolver.git] / JMCR-Stable / real-world application / derby-10.3.2.1 / java / engine / org / apache / derby / iapi / store / access / RowCountable.java

diff --git a/JMCR-Stable/real-world application/derby-10.3.2.1/java/engine/org/apache/derby/iapi/store/access/RowCountable.java b/JMCR-Stable/real-world application/derby-10.3.2.1/java/engine/org/apache/derby/iapi/store/access/RowCountable.java
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+++ b/JMCR-Stable/real-world application/derby-10.3.2.1/java/engine/org/apache/derby/iapi/store/access/RowCountable.java
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+/*\r
+\r
+   Derby - Class org.apache.derby.iapi.store.access.RowCountable\r
+\r
+   Licensed to the Apache Software Foundation (ASF) under one or more\r
+   contributor license agreements.  See the NOTICE file distributed with\r
+   this work for additional information regarding copyright ownership.\r
+   The ASF licenses this file to you under the Apache License, Version 2.0\r
+   (the "License"); you may not use this file except in compliance with\r
+   the License.  You may obtain a copy of the License at\r
+\r
+      http://www.apache.org/licenses/LICENSE-2.0\r
+\r
+   Unless required by applicable law or agreed to in writing, software\r
+   distributed under the License is distributed on an "AS IS" BASIS,\r
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\r
+   See the License for the specific language governing permissions and\r
+   limitations under the License.\r
+\r
+ */\r
+\r
+package org.apache.derby.iapi.store.access;\r
+\r
+import org.apache.derby.iapi.error.StandardException; \r
+\r
+/**\r
+\r
+RowCountable provides the interfaces to read and write row counts in\r
+tables.\r
+<p>\r
+@see ScanController\r
+@see StoreCostController\r
+\r
+**/\r
+\r
+public interface RowCountable\r
+{\r
+    /**\r
+     * Get the total estimated number of rows in the container.\r
+     * <p>\r
+     * The number is a rough estimate and may be grossly off.  In general\r
+     * the server will cache the row count and then occasionally write\r
+     * the count unlogged to a backing store.  If the system happens to \r
+     * shutdown before the store gets a chance to update the row count it\r
+     * may wander from reality.\r
+     * <p>\r
+     * For btree conglomerates this call will return the count of both\r
+     * user rows and internal implementaation rows.  The "BTREE" implementation\r
+     * generates 1 internal implementation row for each page in the btree, and \r
+     * it generates 1 internal implementation row for each branch row.  For\r
+     * this reason it is recommended that clients if possible use the count\r
+     * of rows in the heap table to estimate the number of rows in the index\r
+     * rather than use the index estimated row count.\r
+     *\r
+        * @return The total estimated number of rows in the conglomerate.\r
+     *\r
+        * @exception  StandardException  Standard exception policy.\r
+     **/\r
+    public long getEstimatedRowCount()\r
+               throws StandardException;\r
+\r
+    /**\r
+     * Set the total estimated number of rows in the container.\r
+     * <p>\r
+     * Often, after a scan, the client of RawStore has a much better estimate\r
+     * of the number of rows in the container than what store has.  For \r
+     * instance if we implement some sort of update statistics command, or\r
+     * just after a create index a complete scan will have been done of the\r
+     * table.  In this case this interface allows the client to set the\r
+     * estimated row count for the container, and store will use that number\r
+     * for all future references.\r
+     * <p>\r
+     * This routine can also be used to set the estimated row count in the\r
+     * index to the number of rows in the base table, another workaround for\r
+     * the problem that index estimated row count includes non-user rows.\r
+     *\r
+     * @param count the estimated number of rows in the container.\r
+     *\r
+        * @exception  StandardException  Standard exception policy.\r
+     **/\r
+    public void setEstimatedRowCount(long count)\r
+               throws StandardException;\r
+\r
+}\r