< p >Oracle 11g的流復(fù)制（stream replication）是一種數(shù)據(jù)復(fù)制和同步的技術(shù)，它可以將數(shù)據(jù)庫(kù)的變化流式地傳遞到其他數(shù)據(jù)庫(kù)中。流復(fù)制可以用于各種應(yīng)用場(chǎng)景，例如： 數(shù)據(jù)庫(kù)備份、數(shù)據(jù)中心負(fù)載均衡、實(shí)時(shí)數(shù)據(jù)處理、業(yè)務(wù)分離等。下面我們將詳細(xì)介紹Oracle 11g的流復(fù)制。< p >在Oracle 11g中，流復(fù)制的主要構(gòu)成組件是源端數(shù)據(jù)庫(kù)和目標(biāo)端數(shù)據(jù)庫(kù)。源端數(shù)據(jù)庫(kù)是需要復(fù)制數(shù)據(jù)的數(shù)據(jù)庫(kù)，它包含了需要同步到目標(biāo)端數(shù)據(jù)庫(kù)的數(shù)據(jù)。目標(biāo)端數(shù)據(jù)庫(kù)是接收源端數(shù)據(jù)庫(kù)變化的數(shù)據(jù)庫(kù)，它可以是單個(gè)數(shù)據(jù)庫(kù)也可以是多個(gè)數(shù)據(jù)庫(kù)。這些數(shù)據(jù)庫(kù)之間會(huì)通過(guò)網(wǎng)絡(luò)通信來(lái)實(shí)現(xiàn)數(shù)據(jù)的同步。< p >要使用流復(fù)制，我們需要在源端和目標(biāo)端數(shù)據(jù)庫(kù)上配置相應(yīng)的組件。首先，我們需要在源端數(shù)據(jù)庫(kù)上啟用日志歸檔（archive log），這樣可以確保數(shù)據(jù)庫(kù)中所有的事務(wù)操作都被記錄在歸檔日志中。然后，我們需要在源端和目標(biāo)端數(shù)據(jù)庫(kù)上創(chuàng)建復(fù)制組件（replication objects），例如：發(fā)布者（publisher）、訂閱者（subscriber）、分發(fā)器（distributor）等。< pre >--在源端數(shù)據(jù)庫(kù)上啟用歸檔日志 ALTER DATABASE ARCHIVELOG; --創(chuàng)建發(fā)布者 EXECUTE DBMS_STREAMS_ADM.ADD_TABLE_RULES( table_name =>'hr.employees', streams_type =>'apply', streams_name =>'apply_rules_1', queue_name =>'streams_queue_1', include_dml =>true, include_ddl =>false, source_database =>'source_db' ); --創(chuàng)建訂閱者 EXECUTE DBMS_STREAMS_ADM.ADD_SUBSCRIBER( subscriber_name =>'destination_db', subscriber_address =>'destination_db.example.com', queue_name =>'streams_queue_1', include_dml =>true, include_ddl =>false, source_database =>'source_db' );< p >在創(chuàng)建發(fā)布者和訂閱者之后，我們需要在源端和目標(biāo)端數(shù)據(jù)庫(kù)上啟動(dòng)流復(fù)制。啟動(dòng)流復(fù)制之后，源端數(shù)據(jù)庫(kù)中的所有變化都會(huì)自動(dòng)傳輸?shù)侥繕?biāo)端數(shù)據(jù)庫(kù)中進(jìn)行同步。< pre >--在源端數(shù)據(jù)庫(kù)上啟動(dòng)流復(fù)制 EXECUTE DBMS_STREAMS_ADM.START_REPLICATION( source_object_name_list =>'hr.employees', destination_db_unique_name =>'destination_db', source_db_unique_name =>'source_db', parallelism_mode =>'DEQUEUE_PARALLEL', propagation_mode =>'ASYNC', capture_name =>'capture_1', min_messages =>1, max_messages =>100 ); --在目標(biāo)端數(shù)據(jù)庫(kù)上啟動(dòng)流復(fù)制 EXECUTE DBMS_STREAMS_ADM.START_REPLICATION( source_object_name_list =>'hr.employees', destination_db_unique_name =>'destination_db', source_db_unique_name =>'source_db', parallelism_mode =>'DEQUEUE_PARALLEL', propagation_mode =>'ASYNC', apply_name =>'apply_1', min_messages =>1, max_messages =>100 );< p >除了基本的流復(fù)制配置外，Oracle 11g還提供了高級(jí)的配置選項(xiàng)，例如：過(guò)濾器（filter）、轉(zhuǎn)換器（transformer）等。過(guò)濾器可以用于選擇一部分需要同步的數(shù)據(jù)，而轉(zhuǎn)換器可以用于修改同步的數(shù)據(jù)格式。< pre >--創(chuàng)建過(guò)濾器 CREATE OR REPLACE FUNCTION filter_function( dml_event IN SYS.DBMS_STREAMS_EVTS.STREAMS_EVENT_TYPE, schema_name IN VARCHAR2, object_name IN VARCHAR2) RETURN BOOLEAN AS BEGIN IF dml_event IN ('insert','update') THEN RETURN TRUE; ELSE RETURN FALSE; END IF; END; / EXECUTE DBMS_STREAMS_ADM.ADD_TABLE_RULES( table_name =>'hr.employees', streams_type =>'apply', streams_name =>'apply_rules_2', queue_name =>'streams_queue_2', include_dml =>true, include_ddl =>false, source_database =>'source_db', include_tagged_lcr =>true, dml_condition =>'"SALARY" >1000', rule_set_name =>'my_ruleset_1', rule_type =>DBMS_STREAMS_ADM.RULE_TYPE_SUBSET, rule_condition =>'DEPARTMENT_ID IN (10,20,30)', include_extra_txw =>true, filter_function =>'filter_function' ); --創(chuàng)建轉(zhuǎn)換器 CREATE OR REPLACE FUNCTION transformer_function( dml_event IN SYS.DBMS_STREAMS_EVTS.STREAMS_EVENT_TYPE, ddl_event IN SYS.DBMS_STREAMS_EVTS.STREAMS_EVENT_TYPE, old_tag IN VARCHAR2, new_tag IN VARCHAR2, source_schema IN VARCHAR2, source_object IN VARCHAR2, source_type IN VARCHAR2, source_database IN VARCHAR2, object_id IN NUMBER, object_number IN NUMBER, flags IN NUMBER, column_count IN NUMBER, modified_columns IN SYS.DBMS_STREAMS_INT.LCR_COLUMN_LIST, old_values IN SYS.DBMS_STREAMS_INT.LCR_COLUMN_LIST, new_values IN SYS.DBMS_STREAMS_INT.LCR_COLUMN_LIST) RETURN SYS.DBMS_STREAMS_INT.LCR_ROW_RECORD AS BEGIN --修改列SALARY的值 new_values(2).VARCHAR2_TYPE := '2000'; RETURN SYS.DBMS_STREAMS_INT.LCR_ROW_RECORD( OLD_ROW =>old_values, NEW_ROW =>new_values ); END; / EXECUTE DBMS_STREAMS_ADM.ADD_TABLE_RULES( table_name =>'hr.employees', streams_type =>'apply', streams_name =>'apply_rules_3', queue_name =>'streams_queue_3', include_dml =>true, include_ddl =>false, source_database =>'source_db', include_tagged_lcr =>true, rule_set_name =>'my_ruleset_2', rule_type =>DBMS_STREAMS_ADM.RULE_TYPE_SUBSET, rule_condition =>'DEPARTMENT_ID = 10', include_extra_txw =>true, transformer_function =>'transformer_function' );< p >總之，Oracle 11g的流復(fù)制是一種高效、可靠、靈活的數(shù)據(jù)復(fù)制和同步技術(shù)，它提供了豐富的配置選項(xiàng)，可以滿(mǎn)足各種應(yīng)用場(chǎng)景的需求。如果您想從源端數(shù)據(jù)庫(kù)同步數(shù)據(jù)到目標(biāo)端數(shù)據(jù)庫(kù)中，建議嘗試使用Oracle 11g的流復(fù)制技術(shù)。