[jdbc] support JDBC option to rewrite batch statement to multi-row in…

jdbc/README.md

@@ -106,3 +106,25 @@ db.batchsize=1000             # The number of rows to be batched before commit (
 ```
 
 Please refer to https://github.com/brianfrankcooper/YCSB/wiki/Core-Properties for all other YCSB core properties.
+
+## JDBC Parameter to Improve Insert Performance
+
+Some JDBC drivers support re-writing batched insert statements into multi-row insert statements. This technique can yield order of magnitude improvement in insert statement performance. To enable this feature:
+- **db.batchsize** must be greater than 0.  The magniute of the improvement can be adjusted by varying **batchsize**. Start with a small number and increase at small increments until diminishing return in the improvement is observed. 
+- set **jdbc.batchupdateapi=true** to enable batching.
+- set JDBC driver specific connection parameter in **db.url** to enable the rewrite as shown in the examples below:
+  * MySQL [rewriteBatchedStatements=true](https://dev.mysql.com/doc/connector-j/8.0/en/connector-j-reference-configuration-properties.html)
+
+    ```
+db.url=jdbc:mysql://127.0.0.1:3306/ycsb?rewriteBatchedStatements=true
+```
+  * Postgres [reWriteBatchedInserts=true](https://jdbc.postgresql.org/documentation/head/connect.html#connection-parameters)
+
+    ```
+db.url=jdbc:postgresql://127.0.0.1:5432/ycsb?reWriteBatchedInserts=true
+```
+
+
+
+
+

jdbc/src/main/java/com/yahoo/ycsb/db/JdbcDBClient.java

@@ -421,7 +421,8 @@ public Status insert(String tableName, String key, Map<String, ByteIterator> val
           if (++numRowsInBatch % batchSize == 0) {
             int[] results = insertStatement.executeBatch();
             for (int r : results) {
-              if (r != 1) {
+              // Acceptable values are 1 and SUCCESS_NO_INFO (-2) from reWriteBatchedInserts=true
+              if (r != 1 && r != -2) { 
                 return Status.ERROR;
               }
             }