[JDBC] [Config] Add JDBC Fetch Size Config And Custom Postgres Prepar…

…eStatement (#3478)

* [JDBC] [Config] Add JDBC Fetch Size Config

docs/en/connector-v2/source/Jdbc.md

@@ -32,6 +32,7 @@ supports query SQL and can achieve projection effect.
 | partition_upper_bound        | Long   | No       | -               |
 | partition_lower_bound        | Long   | No       | -               |
 | partition_num                | Int    | No       | job parallelism |
+| fetch_size                   | Int    | No       | 0               |
 | common-options               |        | No       | -               |
 
 
@@ -77,6 +78,11 @@ The partition_column min value for scan, if not set SeaTunnel will query databas
 
 The number of partition count, only support positive integer. default value is job parallelism
 
+### fetch_size [int]
+
+For queries that return a large number of objects, you can configure the row fetch size used in the query to 
+improve performance by reducing the number database hits required to satisfy the selection criteria. Zero means use jdbc default value.
+
 ### common options 
 
 Source plugin common parameters, please refer to [Source Common Options](common-options.md) for details.
@@ -151,3 +157,4 @@ parallel:
 
 - [BugFix] Fix jdbc split bug ([3220](https://github.com/apache/incubator-seatunnel/pull/3220))
 - [Feature] Support Tablestore Source ([3309](https://github.com/apache/incubator-seatunnel/pull/3309))
+- [Feature] Support JDBC Fetch Size Config ([3478](https://github.com/apache/incubator-seatunnel/pull/3478))

seatunnel-connectors-v2/connector-jdbc/src/main/java/org/apache/seatunnel/connectors/seatunnel/jdbc/config/JdbcConfig.java

@@ -48,6 +48,8 @@ public class JdbcConfig implements Serializable {
 
     public static final Option<Integer> BATCH_SIZE = Options.key("batch_size").intType().noDefaultValue().withDescription("batch size");
 
+    public static final Option<Integer> FETCH_SIZE = Options.key("fetch_size").intType().defaultValue(0).withDescription("For queries that return a large number of objects, " +
+        "you can configure the row fetch size used in the query to improve performance by reducing the number database hits required to satisfy the selection criteria. Zero means use jdbc default value.");
 
     public static final Option<Integer> BATCH_INTERVAL_MS = Options.key("batch_interval_ms").intType().noDefaultValue().withDescription("batch interval milliSecond");
 

seatunnel-connectors-v2/connector-jdbc/src/main/java/org/apache/seatunnel/connectors/seatunnel/jdbc/config/JdbcSourceOptions.java

@@ -37,6 +37,7 @@ public class JdbcSourceOptions implements Serializable {
     private String partitionColumn;
     private Long partitionUpperBound;
     private Long partitionLowerBound;
+    private int fetchSize = JdbcConfig.FETCH_SIZE.defaultValue();
     private Integer partitionNumber;
 
     public JdbcSourceOptions(Config config) {
@@ -54,6 +55,9 @@ public JdbcSourceOptions(Config config) {
         if (config.hasPath(JdbcConfig.PARTITION_NUM.key())) {
             this.partitionNumber = config.getInt(JdbcConfig.PARTITION_NUM.key());
         }
+        if (config.hasPath(JdbcConfig.FETCH_SIZE.key())) {
+            this.fetchSize = config.getInt(JdbcConfig.FETCH_SIZE.key());
+        }
     }
 
     public JdbcConnectionOptions getJdbcConnectionOptions() {
@@ -75,4 +79,8 @@ public Optional<Long> getPartitionLowerBound() {
     public Optional<Integer> getPartitionNumber() {
         return Optional.ofNullable(partitionNumber);
     }
+
+    public int getFetchSize() {
+        return fetchSize;
+    }
 }

seatunnel-connectors-v2/connector-jdbc/src/main/java/org/apache/seatunnel/connectors/seatunnel/jdbc/internal/dialect/psql/PostgresDialect.java

@@ -21,11 +21,18 @@
 import org.apache.seatunnel.connectors.seatunnel.jdbc.internal.dialect.JdbcDialect;
 import org.apache.seatunnel.connectors.seatunnel.jdbc.internal.dialect.JdbcDialectTypeMapper;
 
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
 import java.util.Arrays;
 import java.util.Optional;
 import java.util.stream.Collectors;
 
 public class PostgresDialect implements JdbcDialect {
+
+    public static final int DEFAULT_POSTGRES_FETCH_SIZE = 128;
+
     @Override
     public String dialectName() {
         return "PostgreSQL";
@@ -53,4 +60,17 @@ public Optional<String> getUpsertStatement(String tableName, String[] fieldNames
             getInsertIntoStatement(tableName, fieldNames), uniqueColumns, updateClause);
         return Optional.of(upsertSQL);
     }
+
+    @Override
+    public PreparedStatement creatPreparedStatement(Connection connection, String queryTemplate, int fetchSize) throws SQLException {
+        // use cursor mode, reference: https://jdbc.postgresql.org/documentation/query/#getting-results-based-on-a-cursor
+        connection.setAutoCommit(false);
+        PreparedStatement statement = connection.prepareStatement(queryTemplate, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
+        if (fetchSize > 0) {
+            statement.setFetchSize(fetchSize);
+        } else {
+            statement.setFetchSize(DEFAULT_POSTGRES_FETCH_SIZE);
+        }
+        return statement;
+    }
 }

seatunnel-connectors-v2/connector-jdbc/src/main/java/org/apache/seatunnel/connectors/seatunnel/jdbc/source/JdbcSource.java

@@ -88,8 +88,8 @@ public void prepare(Config pluginConfig) throws PrepareFailException {
             jdbcDialect,
             typeInfo,
             query,
-            0,
-            true
+            jdbcSourceOptions.getFetchSize(),
+            jdbcSourceOptions.getJdbcConnectionOptions().isAutoCommit()
         );
     }