如何确定CacheJdbcBlobStore表项的正确大小？

Question

我正在尝试为我的Apache应用程序设置一个持久缓存存储。我尝试使用的缓存存储是CacheJdbcBlobStore。下面是我在我的原型中使用的软件列表：

• JDK 1.8.0_66
• Apache Tomcat 7.0.68
• 1.6.0
• HyperSQL 2.3.4

我的数据源在Spring中设置如下：

<bean id="myDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="org.hsqldb.jdbcDriver"/>
    <property name="url" value="jdbc:hsqldb:http://localhost"/>
    <property name="username" value="sa"/>
    <property name="password" value=""/>
</bean>

以及Ignite配置：

<bean id="ignite.cfg" class="org.apache.ignite.configuration.IgniteConfiguration">
    <property name="cacheConfiguration">
        <list>
            <bean class="org.apache.ignite.configuration.CacheConfiguration">
                <property name="cacheMode" value="REPLICATED"/>
                <property name="name" value="session-cache"/>
                <property name="cacheStoreFactory">
                    <bean class="org.apache.ignite.cache.store.jdbc.CacheJdbcBlobStoreFactory">
                        <property name="dataSourceBean" value="myDataSource" />
                    </bean>
                </property>
                <property name="readThrough" value="true" />
                <property name="writeThrough" value="true" />                               
            </bean>
        </list>
    </property>
</bean>

然而，当我运行应用程序时，我得到了以下异常：

ERROR - root                       - Failed to update web session: null
class org.apache.ignite.IgniteException: Failed to save session: C56AF4E1DA01A439E43E512950D32D45
Caused by: javax.cache.integration.CacheWriterException: class org.apache.ignite.internal.processors.cache.CachePartialUpdateCheckedException: Failed to update keys (retry update if possible).: [C56AF4E1DA
01A439E43E512950D32D45]
Caused by: class org.apache.ignite.internal.processors.cache.CachePartialUpdateCheckedException: Failed to update keys (retry update if possible).: [C56AF4E1DA01A439E43E512950D32D45]
                Suppressed: class org.apache.ignite.IgniteCheckedException: Failed to put object [key=C56AF4E1DA01A439E43E512950D32D45, val=WebSessionEntity [id=C56AF4E1DA01A439E43E512950D32D45, createTime=1464182374328, accessTime=1464182374330, maxInactiveInterval=1800, attributes=[]]]
                        at org.apache.ignite.internal.processors.cache.store.GridCacheStoreManagerAdapter.put(GridCacheStoreManagerAdapter.java:583)
                        at org.apache.ignite.internal.processors.cache.GridCacheMapEntry.innerUpdate(GridCacheMapEntry.java:2358)
                        at org.apache.ignite.internal.processors.cache.distributed.dht.atomic.GridDhtAtomicCache.updateSingle(GridDhtAtomicCache.java:2246)
                        ... 37 more
                Caused by: javax.cache.integration.CacheWriterException: Failed to put object [key=C56AF4E1DA01A439E43E512950D32D45, val=WebSessionEntity [id=C56AF4E1DA01A439E43E512950D32D45, createTime=1464182374328, accessTime=1464182374330, maxInactiveInterval=1800, attributes=[]]]
                        at org.apache.ignite.cache.store.jdbc.CacheJdbcBlobStore.write(CacheJdbcBlobStore.java:281)
                        at org.apache.ignite.internal.processors.cache.store.GridCacheStoreManagerAdapter.put(GridCacheStoreManagerAdapter.java:575)
                        ... 39 more
                Caused by: java.sql.SQLDataException: data exception: string data, right truncation;  table: ENTRIES column: AKEY
                        at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
                        at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
                        at org.hsqldb.jdbc.JDBCPreparedStatement.fetchResult(Unknown Source)
                        at org.hsqldb.jdbc.JDBCPreparedStatement.executeUpdate(Unknown Source)
                        at org.apache.ignite.cache.store.jdbc.CacheJdbcBlobStore.write(CacheJdbcBlobStore.java:277)
                        ... 40 more

我已经知道您需要将createTableQuery属性添加到jdbc.CacheJdbcBlobStoreFactory中：

<bean class="org.apache.ignite.cache.store.jdbc.CacheJdbcBlobStoreFactory">
    ...
    <property name="createTableQuery" value="create table if not exists ENTRIES (akey VARBINARY(100) primary key, val BLOB(10k))" />
</bean>

以便重写默认的：

create table if not exists ENTRIES (akey binary primary key, val binary)

我的问题是:如何确定表条目(特别是val列)的大小？现在我下了一万块。如果我设置的大小太高，这将是浪费，但如果我把尺寸太低，我会得到上面提到的例外迟早。谢谢。

Answer 1

也许您不必担心表条目的列大小。例如，在HyperSQL数据库中，如果以下列方式创建表：

create table if not exists ENTRIES (akey VARBINARY(100) primary key, val BLOB(10k))

10k是val列的最大大小，而不是实际占用的空间。因此，如果实际长度低于最大限度，就不会造成浪费。

在Oracle中，您可以如下所示创建表：

create table ENTRIES (akey VARCHAR2(100) primary key, val BLOB);

再说一遍，您不必担心val列的大小。在Oracle中，BLOB类型列的大小可以看作是无限的大小初始化参数(8 TB到128 TB)。实际占用的空间取决于缓存的实际大小。空间是不会浪费的。