Apache Tomcat JDBC Connection Pool bad performance on batch \ bulk inserts

Question

I have recently incorporated the Apache Tomcat JDBC Connection Pool to my application (using MySQL DB). I tried using Apache DBCP before, but didn't like its results, and the tomcat implementation seemed to fit my needs even though I run a standalone java application and don't use tomcat at all.

Recently, I encountered a huge performance problem when executing batch (aka bulk ) insert queries.

I have a flow in which I insert ~2500 records to a table in a batched fashion. It takes forever when using the jdbc connection pool, compared to a few seconds when reverting back to opening a connection for each query (no pooling).

I wrote a small application that inserts 30 rows to the same table. It takes 12 seconds when pooling, and ~ 800 millis when not pooling.

Prior to using the connection pool, I used com.mysql.jdbc.jdbc2.optional.MysqlDataSource as my DataSource. The connection was configured with the following line:

dataSource.setRewriteBatchedStatements(true);

I'm quite sure that this is the core difference between the two approaches, but couldn't find an equivalent parameter in jdbc-pool.

sibnick sibnick · Accepted Answer · 2015-09-29T17:11:27

MySql JDBC driver does not support batch operations. RewriteBatchedStatement is the best that you can get. Here the code from mysql PreparedStatement.java:

 try {
            statementBegins();

            clearWarnings();

            if (!this.batchHasPlainStatements && this.connection.getRewriteBatchedStatements()) {

                if (canRewriteAsMultiValueInsertAtSqlLevel()) {
                    return executeBatchedInserts(batchTimeout);
                }

                if (this.connection.versionMeetsMinimum(4, 1, 0) && !this.batchHasPlainStatements && this.batchedArgs != null
                        && this.batchedArgs.size() > 3 /* cost of option setting rt-wise */) {
                    return executePreparedBatchAsMultiStatement(batchTimeout);
                }
            }

            return executeBatchSerially(batchTimeout);
        } finally {
            this.statementExecuting.set(false);

            clearBatch();
        }

It is one of the reason why I do not like MySql and prefer Postgres

EDIT:

You should combine connection pool, batch operation, and RewriteBatchedStatement option. You can set RewriteBatchedStatement option through jdbc url parameter: jdbc:mysql://localhost:3307/mydb?rewriteBatchedStatements=true

Apache Tomcat JDBC Connection Pool bad performance on batch \ bulk inserts

1 Answers