fix: ensure executeBatch() does not use server-side prepared statemen…

…ts when prepareThreshold=0 (#690)

pgjdbc/src/main/java/org/postgresql/jdbc/PgStatement.java

@@ -735,7 +735,7 @@ protected BatchResultHandler createBatchHandler(Query[] queries,
        // If executing the same query twice in a batch, make sure the statement
        // is server-prepared. In other words, "oneshot" only if the query is one in the batch
        // or the queries are different
        && isOneShotQuery(null)) {
        || isOneShotQuery(null)) {
      flags |= QueryExecutor.QUERY_ONESHOT;
    } else {
      // If a batch requests generated keys and isn't already described,

pgjdbc/src/test/java/org/postgresql/test/jdbc2/BaseTest4.java

@@ -69,4 +69,8 @@ public void assumeCallableStatementsSupported() {
    Assume.assumeTrue("callable statements are not fully supported in simple protocol execution mode",
        preferQueryMode.compareTo(PreferQueryMode.EXTENDED) >= 0);
  }

  public void assumeBinaryModeRegular() {
    Assume.assumeTrue(binaryMode == BinaryMode.REGULAR);
  }
}

pgjdbc/src/test/java/org/postgresql/test/jdbc2/PreparedStatementTest.java

@@ -11,10 +11,12 @@
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;

import org.postgresql.jdbc.PgStatement;
import org.postgresql.jdbc.PreferQueryMode;
import org.postgresql.test.TestUtil;
import org.postgresql.test.util.BrokenInputStream;

import org.junit.Assume;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
@@ -1063,4 +1065,64 @@ public void testStatementDescribe() throws SQLException {
    pstmt.close();
  }

  @Test
  public void testBatchWithPrepareThreshold5() throws SQLException {
    assumeBinaryModeRegular();
    Assume.assumeTrue("simple protocol only does not support prepared statement requests",
        preferQueryMode != PreferQueryMode.SIMPLE);

    PreparedStatement pstmt = con.prepareStatement("CREATE temp TABLE batch_tab_threshold5 (id bigint, val bigint)");
    pstmt.executeUpdate();
    pstmt.close();

    // When using a prepareThreshold of 5, a batch update should use server-side prepare
    pstmt = con.prepareStatement("INSERT INTO batch_tab_threshold5 (id, val) VALUES (?,?)");
    ((PgStatement) pstmt).setPrepareThreshold(5);
    for (int p = 0; p < 5; p++) {
      for (int i = 0; i <= 5; i++) {
        pstmt.setLong(1, i);
        pstmt.setLong(2, i);
        pstmt.addBatch();
      }
      pstmt.executeBatch();
    }
    pstmt.close();
    pstmt = con.prepareStatement("select count(*) from pg_prepared_statements where statement = 'INSERT INTO batch_tab_threshold5 (id, val) VALUES ($1,$2)'");
    ResultSet rs = pstmt.executeQuery();
    assertTrue(rs.next());
    assertEquals(1, rs.getInt(1));
    rs.close();
    pstmt.close();
  }

  @Test
  public void testBatchWithPrepareThreshold0() throws SQLException {
    assumeBinaryModeRegular();
    Assume.assumeTrue("simple protocol only does not support prepared statement requests",
        preferQueryMode != PreferQueryMode.SIMPLE);

    PreparedStatement pstmt = con.prepareStatement("CREATE temp TABLE batch_tab_threshold0 (id bigint, val bigint)");
    pstmt.executeUpdate();
    pstmt.close();

    // When using a prepareThreshold of 0, a batch update should not use server-side prepare
    pstmt = con.prepareStatement("INSERT INTO batch_tab_threshold0 (id, val) VALUES (?,?)");
    ((PgStatement) pstmt).setPrepareThreshold(0);
    for (int p = 0; p < 5; p++) {
      for (int i = 0; i <= 5; i++) {
        pstmt.setLong(1, i);
        pstmt.setLong(2, i);
        pstmt.addBatch();
      }
      pstmt.executeBatch();
    }
    pstmt.close();
    pstmt = con.prepareStatement("select count(*) from pg_prepared_statements where statement = 'INSERT INTO batch_tab_threshold0 (id, val) VALUES ($1,$2)'");
    ResultSet rs = pstmt.executeQuery();
    assertTrue(rs.next());
    assertEquals(0, rs.getInt(1));
    rs.close();
    pstmt.close();
  }

}