postgresql - preferredTestQuery 从不与 c3p0 0.9.5.2 和 Tomcat 7 一起使用

Question

我将 tomcat7 与 c3p0-0.9.5.2 和 postgresql-9.3-1102-jdbc41 一起使用，preferredTestQuery(选择 1)从不使用，仅在产品中使用。

相同的配置在测试环境中工作正常(检查更新查询)。

在产品中有很多对 getTable postgresql 查询的调用。 (> 1000cpm - New Relic 数据)。

 <Resource name="jdbc/database_read_only"
          auth="Container"
          type="com.mchange.v2.c3p0.ComboPooledDataSource"
          description="Ma description"
          jdbcUrl="jdbc:postgresql://hostname:5432/mabase"
          driverClass="org.postgresql.Driver"
          user="monuser"
          password="monpassword"
          initialPoolSize="10"
          minPoolSize="10"
          maxPoolSize="100"
          acquireIncrement="10"
          maxIdleTime="300"
          maxConnectionAge="1800"
          connectionTesterClassName="com.mchange.v2.c3p0.impl.DefaultConnectionTester"
          preferredTestQuery="select 2"
          testConnectionOnCheckout="true"
          testConnectionOnCheckin="false"
          idleConnectionTestPeriod="300"
          maxIdleTimeExcessConnections="60"
          unreturnedConnectionTimeout="10"
          factory="org.apache.naming.factory.BeanFactory"/>

日志看起来不错:

 2016-12-23 15:26:10,138 : Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 10, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> ddsdsdsqd, debugUnreturnedConnectionStackTraces -> false, description -> ma description, driverClass -> org.postgresql.Driver, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> mytoken, idleConnectionTestPeriod -> 300, initialPoolSize -> 10, jdbcUrl -> jdbc:postgresql://hostname:5432/monapp, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 1800, maxIdleTime -> 300, maxIdleTimeExcessConnections -> 60, maxPoolSize -> 100, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 10, numHelperThreads -> 3, preferredTestQuery -> select 1, privilegeSpawnedThreads -> false, properties -> {user=******, password=******}, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> true, unreturnedConnectionTimeout -> 0, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]

为什么 c3p0 使用复杂请求而不是“select 1”？

复杂请求示例:

SELECT * FROM (SELECT n.nspname,c.relname,a.attname,a.atttypid,a.attnotnull OR (t.typtype = 'd' AND t.typnotnull) AS attnotnull,a.atttypmod,a.attlen,row_number() OVER (PARTITION BY a.attrelid ORDER BY a.attnum) AS attnum, pg_catalog.pg_get_expr(def.adbin, def.adrelid) AS adsrc,dsc.description,t.typbasetype,t.typtype FROM pg_catalog.pg_namespace

SELECT NULL AS TABLE_CAT, n.nspname AS TABLE_SCHEM, c.relname AS TABLE_NAME,  CASE n.nspname ~ '^pg_' OR n.nspname = 'information_schema'  WHEN true THEN CASE  WHEN n.nspname = 'pg_catalog' OR n.nspname = 'information_schema' THEN CASE c.relkind   WHEN 'r' THEN 'SYSTEM TABLE'   WHEN 'v' THEN 'SYSTEM VIEW'   WHEN 'i' THEN 'SYSTEM INDEX'   ELSE NULL   END  WHEN n.nspname = 'pg_toast' THEN CASE c.relkind   WHEN 'r' THEN 'SYSTEM TOAST TABLE'   WHEN 'i' THEN 'SYSTEM TOAST INDEX'   ELSE NULL   END  ELSE CASE c.relkind   WHEN 'r' THEN 'TEMPORARY TABLE'   WHEN 'i' THEN 'TEMPORARY INDEX'   WHEN 'S' THEN 'TEMPORARY SEQUENCE'   WHEN 'v' THEN 'TEMPORARY VIEW'   ELSE NULL   END  END  WHEN false THEN CASE c.relkind  WHEN 'r' THEN 'TABLE'  WHEN 'i' THEN 'INDEX'  WHEN 'S' THEN 'SEQUENCE'  WHEN 'v' THEN 'VIEW'  WHEN 'c' THEN 'TYPE'  WHEN 'f' THEN 'FOREIGN TABLE'  WHEN 'm' THEN 'MATERIALIZED VIEW'  ELSE NULL  END  ELSE NULL  END  AS TABLE_TYPE, d.description AS REMARKS  FROM pg_catalog.pg_namespace n, pg_catalog.pg_class c  LEFT JOIN pg_catalog.pg_description d ON (c.oid = d.objoid AND d.objsubid = 0)  LEFT JOIN pg_catalog.pg_class dc ON (d.classoid=dc.oid AND dc.relname='pg_class')  LEFT JOIN pg_catalog.pg_namespace dn ON (dn.oid=dc.relnamespace AND dn.nspname='pg_catalog')  WHERE c.relnamespace = n.oid  AND c.relname LIKE 'availability_table' ORDER BY TABLE_TYPE,TABLE_SCHEM,TABLE_NAME 

我接受所有的想法。

谢谢

Answer 1

我不认为您正在使用您认为正在使用的东西。

针对 Postgres 的 JDBC 4.1 驱动程序运行的 c3p0-0.9.5.2 永远不会使用旧的默认表名查询。如果未设置 preferredTestQuery，它将使用 Connection.isValid(...) 方法。我怀疑您的应用程序的 CLASSPATH 中某处有旧版本的 c3p0 和/或 Postgres JDBC。

请注意，您应该尝试在您发布的内容中追查其中的怪异之处。您实际配置的preferredTestQuery是“select 2”，而您日志中DataSource的preferredTestQuery是“select 1”。同样，您将 unreturnedConnectionTimeout 配置为 10，但在记录的配置中它未设置 (0)。您正在记录一个与您正在配置的数据源相似但不同的数据源。

我怀疑生产环境中事情变得奇怪的原因是因为在您的生产环境而非测试环境中，您有较旧的库(c3p0 和/或 postgres 驱动程序)和其他 DataSources 设置较旧的应用程序。

请注意，c3p0 的语义非常稳定。如果您在任何地方升级到 0.9.5.2，它不太可能损害您的旧应用程序。 (只要确保包括它的依赖项 mchange-commons-java 0.2.11 或更高版本。)