mysql & java & spring transaction isolation level
mysql
/*SESSION LEVEL*/ select @@tx_isolation; /*GLOBAL LEVEL*/ select @@global.tx_isolation; select 'SESSION' as scope,@@tx_isolation UNION select 'GLOBAL' as scope,@@global.tx_isolation; -- SESSION REPEATABLE-READ -- GLOBAL REPEATABLE-READ
java.sql;
Connection
/** * A constant indicating that transactions are not supported. */ int TRANSACTION_NONE = 0; /** * A constant indicating that * dirty reads, non-repeatable reads and phantom reads can occur. * This level allows a row changed by one transaction to be read * by another transaction before any changes in that row have been * committed (a "dirty read"). If any of the changes are rolled back, * the second transaction will have retrieved an invalid row. */ int TRANSACTION_READ_UNCOMMITTED = 1; /** * A constant indicating that * dirty reads are prevented; non-repeatable reads and phantom * reads can occur. This level only prohibits a transaction * from reading a row with uncommitted changes in it. */ int TRANSACTION_READ_COMMITTED = 2; /** * A constant indicating that * dirty reads and non-repeatable reads are prevented; phantom * reads can occur. This level prohibits a transaction from * reading a row with uncommitted changes in it, and it also * prohibits the situation where one transaction reads a row, * a second transaction alters the row, and the first transaction * rereads the row, getting different values the second time * (a "non-repeatable read"). */ int TRANSACTION_REPEATABLE_READ = 4; /** * A constant indicating that * dirty reads, non-repeatable reads and phantom reads are prevented. * This level includes the prohibitions in * <code>TRANSACTION_REPEATABLE_READ</code> and further prohibits the * situation where one transaction reads all rows that satisfy * a <code>WHERE</code> condition, a second transaction inserts a row that * satisfies that <code>WHERE</code> condition, and the first transaction * rereads for the same condition, retrieving the additional * "phantom" row in the second read. */ int TRANSACTION_SERIALIZABLE = 8; /** * Attempts to change the transaction isolation level for this * <code>Connection</code> object to the one given. * The constants defined in the interface <code>Connection</code> * are the possible transaction isolation levels. * <P> * <B>Note:</B> If this method is called during a transaction, the result * is implementation-defined. * * @param level one of the following <code>Connection</code> constants: * <code>Connection.TRANSACTION_READ_UNCOMMITTED</code>, * <code>Connection.TRANSACTION_READ_COMMITTED</code>, * <code>Connection.TRANSACTION_REPEATABLE_READ</code>, or * <code>Connection.TRANSACTION_SERIALIZABLE</code>. * (Note that <code>Connection.TRANSACTION_NONE</code> cannot be used * because it specifies that transactions are not supported.) * @exception SQLException if a database access error occurs, this * method is called on a closed connection * or the given parameter is not one of the <code>Connection</code> * constants * @see DatabaseMetaData#supportsTransactionIsolationLevel * @see #getTransactionIsolation */ void setTransactionIsolation(int level) throws SQLException; /** * Retrieves this <code>Connection</code> object's current * transaction isolation level. * * @return the current transaction isolation level, which will be one * of the following constants: * <code>Connection.TRANSACTION_READ_UNCOMMITTED</code>, * <code>Connection.TRANSACTION_READ_COMMITTED</code>, * <code>Connection.TRANSACTION_REPEATABLE_READ</code>, * <code>Connection.TRANSACTION_SERIALIZABLE</code>, or * <code>Connection.TRANSACTION_NONE</code>. * @exception SQLException if a database access error occurs * or this method is called on a closed connection * @see #setTransactionIsolation */ int getTransactionIsolation() throws SQLException;
org.springframework.transaction;
TransactionDefinitio/**
* Interface that defines Spring-compliant transaction properties. * Based on the propagation behavior definitions analogous to EJB CMT attributes. * * <p>Note that isolation level and timeout settings will not get applied unless * an actual new transaction gets started. As only {@link #PROPAGATION_REQUIRED}, * {@link #PROPAGATION_REQUIRES_NEW} and {@link #PROPAGATION_NESTED} can cause * that, it usually doesn't make sense to specify those settings in other cases. * Furthermore, be aware that not all transaction managers will support those * advanced features and thus might throw corresponding exceptions when given * non-default values. * * <p>The {@link #isReadOnly() read-only flag} applies to any transaction context, * whether backed by an actual resource transaction or operating non-transactionally * at the resource level. In the latter case, the flag will only apply to managed * resources within the application, such as a Hibernate {@code Session}. * * @author Juergen Hoeller * @since 08.05.2003 * @see PlatformTransactionManager#getTransaction(TransactionDefinition) * @see org.springframework.transaction.support.DefaultTransactionDefinition * @see org.springframework.transaction.interceptor.TransactionAttribute */ public interface TransactionDefinition { /** * Support a current transaction; create a new one if none exists. * Analogous to the EJB transaction attribute of the same name. * <p>This is typically the default setting of a transaction definition, * and typically defines a transaction synchronization scope. */ int PROPAGATION_REQUIRED = 0; /** * Support a current transaction; execute non-transactionally if none exists. * Analogous to the EJB transaction attribute of the same name. * <p><b>NOTE:</b> For transaction managers with transaction synchronization, * {@code PROPAGATION_SUPPORTS} is slightly different from no transaction * at all, as it defines a transaction scope that synchronization might apply to. * As a consequence, the same resources (a JDBC {@code Connection}, a * Hibernate {@code Session}, etc) will be shared for the entire specified * scope. Note that the exact behavior depends on the actual synchronization * configuration of the transaction manager! * <p>In general, use {@code PROPAGATION_SUPPORTS} with care! In particular, do * not rely on {@code PROPAGATION_REQUIRED} or {@code PROPAGATION_REQUIRES_NEW} * <i>within</i> a {@code PROPAGATION_SUPPORTS} scope (which may lead to * synchronization conflicts at runtime). If such nesting is unavoidable, make sure * to configure your transaction manager appropriately (typically switching to * "synchronization on actual transaction"). * @see org.springframework.transaction.support.AbstractPlatformTransactionManager#setTransactionSynchronization * @see org.springframework.transaction.support.AbstractPlatformTransactionManager#SYNCHRONIZATION_ON_ACTUAL_TRANSACTION */ int PROPAGATION_SUPPORTS = 1; /** * Support a current transaction; throw an exception if no current transaction * exists. Analogous to the EJB transaction attribute of the same name. * <p>Note that transaction synchronization within a {@code PROPAGATION_MANDATORY} * scope will always be driven by the surrounding transaction. */ int PROPAGATION_MANDATORY = 2; /** * Create a new transaction, suspending the current transaction if one exists. * Analogous to the EJB transaction attribute of the same name. * <p><b>NOTE:</b> Actual transaction suspension will not work out-of-the-box * on all transaction managers. This in particular applies to * {@link org.springframework.transaction.jta.JtaTransactionManager}, * which requires the {@code javax.transaction.TransactionManager} to be * made available it to it (which is server-specific in standard Java EE). * <p>A {@code PROPAGATION_REQUIRES_NEW} scope always defines its own * transaction synchronizations. Existing synchronizations will be suspended * and resumed appropriately. * @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager */ int PROPAGATION_REQUIRES_NEW = 3; /** * Do not support a current transaction; rather always execute non-transactionally. * Analogous to the EJB transaction attribute of the same name. * <p><b>NOTE:</b> Actual transaction suspension will not work out-of-the-box * on all transaction managers. This in particular applies to * {@link org.springframework.transaction.jta.JtaTransactionManager}, * which requires the {@code javax.transaction.TransactionManager} to be * made available it to it (which is server-specific in standard Java EE). * <p>Note that transaction synchronization is <i>not</i> available within a * {@code PROPAGATION_NOT_SUPPORTED} scope. Existing synchronizations * will be suspended and resumed appropriately. * @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager */ int PROPAGATION_NOT_SUPPORTED = 4; /** * Do not support a current transaction; throw an exception if a current transaction * exists. Analogous to the EJB transaction attribute of the same name. * <p>Note that transaction synchronization is <i>not</i> available within a * {@code PROPAGATION_NEVER} scope. */ int PROPAGATION_NEVER = 5; /** * Execute within a nested transaction if a current transaction exists, * behave like {@link #PROPAGATION_REQUIRED} else. There is no analogous * feature in EJB. * <p><b>NOTE:</b> Actual creation of a nested transaction will only work on * specific transaction managers. Out of the box, this only applies to the JDBC * {@link org.springframework.jdbc.datasource.DataSourceTransactionManager} * when working on a JDBC 3.0 driver. Some JTA providers might support * nested transactions as well. * @see org.springframework.jdbc.datasource.DataSourceTransactionManager */ int PROPAGATION_NESTED = 6; /** * Use the default timeout of the underlying transaction system, * or none if timeouts are not supported. */ int TIMEOUT_DEFAULT = -1; /** * Return the propagation behavior. * <p>Must return one of the {@code PROPAGATION_XXX} constants * defined on {@link TransactionDefinition this interface}. * @return the propagation behavior * @see #PROPAGATION_REQUIRED * @see org.springframework.transaction.support.TransactionSynchronizationManager#isActualTransactionActive() */ int getPropagationBehavior(); /** * Return the isolation level. * <p>Must return one of the {@code ISOLATION_XXX} constants * defined on {@link TransactionDefinition this interface}. * <p>Only makes sense in combination with {@link #PROPAGATION_REQUIRED} * or {@link #PROPAGATION_REQUIRES_NEW}. * <p>Note that a transaction manager that does not support custom isolation levels * will throw an exception when given any other level than {@link #ISOLATION_DEFAULT}. * @return the isolation level */ int getIsolationLevel(); /** * Return the transaction timeout. * <p>Must return a number of seconds, or {@link #TIMEOUT_DEFAULT}. * <p>Only makes sense in combination with {@link #PROPAGATION_REQUIRED} * or {@link #PROPAGATION_REQUIRES_NEW}. * <p>Note that a transaction manager that does not support timeouts will throw * an exception when given any other timeout than {@link #TIMEOUT_DEFAULT}. * @return the transaction timeout */ int getTimeout(); /** * Return whether to optimize as a read-only transaction. * <p>The read-only flag applies to any transaction context, whether * backed by an actual resource transaction * ({@link #PROPAGATION_REQUIRED}/{@link #PROPAGATION_REQUIRES_NEW}) or * operating non-transactionally at the resource level * ({@link #PROPAGATION_SUPPORTS}). In the latter case, the flag will * only apply to managed resources within the application, such as a * Hibernate {@code Session}. << * <p>This just serves as a hint for the actual transaction subsystem; * it will <i>not necessarily</i> cause failure of write access attempts. * A transaction manager which cannot interpret the read-only hint will * <i>not</i> throw an exception when asked for a read-only transaction. * @return {@code true} if the transaction is to be optimized as read-only * @see org.springframework.transaction.support.TransactionSynchronization#beforeCommit(boolean) * @see org.springframework.transaction.support.TransactionSynchronizationManager#isCurrentTransactionReadOnly() */ boolean isReadOnly(); /** * Return the name of this transaction. Can be {@code null}. * <p>This will be used as the transaction name to be shown in a * transaction monitor, if applicable (for example, WebLogic's). * <p>In case of Spring's declarative transactions, the exposed name will be * the {@code fully-qualified class name + "." + method name} (by default). * @return the name of this transaction * @see org.springframework.transaction.interceptor.TransactionAspectSupport * @see org.springframework.transaction.support.TransactionSynchronizationManager#getCurrentTransactionName() */ String getName(); }
org.springframework.transaction.annotation；
enum Isolation
/** * Enumeration that represents transaction isolation levels for use * with the {@link Transactional} annotation, corresponding to the * {@link TransactionDefinition} interface. * * @author Colin Sampaleanu * @author Juergen Hoeller * @since 1.2 */ public enum Isolation { /** * Use the default isolation level of the underlying datastore. * All other levels correspond to the JDBC isolation levels. * @see java.sql.Connection */ DEFAULT(TransactionDefinition.ISOLATION_DEFAULT), /** * A constant indicating that dirty reads, non-repeatable reads and phantom reads * can occur. This level allows a row changed by one transaction to be read by * another transaction before any changes in that row have been committed * (a "dirty read"). If any of the changes are rolled back, the second * transaction will have retrieved an invalid row. * @see java.sql.Connection#TRANSACTION_READ_UNCOMMITTED */ READ_UNCOMMITTED(TransactionDefinition.ISOLATION_READ_UNCOMMITTED), /** * A constant indicating that dirty reads are prevented; non-repeatable reads * and phantom reads can occur. This level only prohibits a transaction * from reading a row with uncommitted changes in it. * @see java.sql.Connection#TRANSACTION_READ_COMMITTED */ READ_COMMITTED(TransactionDefinition.ISOLATION_READ_COMMITTED), /** * A constant indicating that dirty reads and non-repeatable reads are * prevented; phantom reads can occur. This level prohibits a transaction * from reading a row with uncommitted changes in it, and it also prohibits * the situation where one transaction reads a row, a second transaction * alters the row, and the first transaction rereads the row, getting * different values the second time (a "non-repeatable read"). * @see java.sql.Connection#TRANSACTION_REPEATABLE_READ */ REPEATABLE_READ(TransactionDefinition.ISOLATION_REPEATABLE_READ), /** * A constant indicating that dirty reads, non-repeatable reads and phantom * reads are prevented. This level includes the prohibitions in * {@code ISOLATION_REPEATABLE_READ} and further prohibits the situation * where one transaction reads all rows that satisfy a {@code WHERE} * condition, a second transaction inserts a row that satisfies that * {@code WHERE} condition, and the first transaction rereads for the * same condition, retrieving the additional "phantom" row in the second read. * @see java.sql.Connection#TRANSACTION_SERIALIZABLE */ SERIALIZABLE(TransactionDefinition.ISOLATION_SERIALIZABLE); private final int value; Isolation(int value) { this.value = value; } public int value() { return this.value; } }
org.springframework.transaction;
TransactionDefinitio/**
/** * Use the default isolation level of the underlying datastore. * All other levels correspond to the JDBC isolation levels. * @see java.sql.Connection */ int ISOLATION_DEFAULT = -1; /** * Indicates that dirty reads, non-repeatable reads and phantom reads * can occur. * <p>This level allows a row changed by one transaction to be read by another * transaction before any changes in that row have been committed (a "dirty read"). * If any of the changes are rolled back, the second transaction will have * retrieved an invalid row. * @see java.sql.Connection#TRANSACTION_READ_UNCOMMITTED */ int ISOLATION_READ_UNCOMMITTED = Connection.TRANSACTION_READ_UNCOMMITTED; /** * Indicates that dirty reads are prevented; non-repeatable reads and * phantom reads can occur. * <p>This level only prohibits a transaction from reading a row * with uncommitted changes in it. * @see java.sql.Connection#TRANSACTION_READ_COMMITTED */ int ISOLATION_READ_COMMITTED = Connection.TRANSACTION_READ_COMMITTED; /** * Indicates that dirty reads and non-repeatable reads are prevented; * phantom reads can occur. * <p>This level prohibits a transaction from reading a row with uncommitted changes * in it, and it also prohibits the situation where one transaction reads a row, * a second transaction alters the row, and the first transaction re-reads the row, * getting different values the second time (a "non-repeatable read"). * @see java.sql.Connection#TRANSACTION_REPEATABLE_READ */ int ISOLATION_REPEATABLE_READ = Connection.TRANSACTION_REPEATABLE_READ; /** * Indicates that dirty reads, non-repeatable reads and phantom reads * are prevented. * <p>This level includes the prohibitions in {@link #ISOLATION_REPEATABLE_READ} * and further prohibits the situation where one transaction reads all rows that * satisfy a {@code WHERE} condition, a second transaction inserts a row * that satisfies that {@code WHERE} condition, and the first transaction * re-reads for the same condition, retrieving the additional "phantom" row * in the second read. * @see java.sql.Connection#TRANSACTION_SERIALIZABLE */ int ISOLATION_SERIALIZABLE = Connection.TRANSACTION_SERIALIZABLE;
