OGG複製程序延遲高，我們前面講述的方法及場景是,sql update or delete 操作,修改少量記錄但是SQL使用低效的索引甚至是全表掃描，導致複製程序延遲很高，通過建立索引和固定或收集統計資訊讓Oracle SQL選擇好的索引，從而加快複製速度。

但是如果一個表大量的insert 操作呢？？？ insert 走啥索引，只是寫資料！！！ 併發很高，如何加快寫入呢？？？

本篇文章講述通過OGG 引數將Oracle 一個表拆分為多個程序，類似並行的套路加快速度。

一、引數說明,測試使用的是19.1 OGG版本引數

@RANGE
Use the @RANGE function to divide the rows of any table across two or more Oracle GoldenGate processes. It can be used to increase the throughput
 
 of large and heavily accessed tables and also can be used to divide data into sets for distribution to different destinations. Specify each range
 in a FILTER clause in a TABLE or MAP statement.

@RANGE is safe and scalable. It preserves data integrity by guaranteeing that the same row will always be processed by the same process group. To
 
 ensure that rows do not shift partitions to another process group and that the DML is performed in the correct order, the column on which you base

 the @RANGE partitioning must not ever change during a process run. Updates to the partition column may result in "row not found" errors or
 unique-constraint errors.

@RANGE computes a hash value of the columns specified 
 
in the input. If no columns are specified, the KEYCOLS clause of the TABLE or MAP statement
 is used to determine the columns to hash, if a KEYCOLS clause exists. Otherwise, the primary key columns are used.

Oracle GoldenGate adjusts the total number of ranges to optimize the even distribution across the number of ranges specified.

Because any columns can be specified for this function, rows in tables with relational constraints to one another must be grouped together into
 the same process or trail to preserve referential integrity.

Note: Using Extract to calculate the ranges is more efficient than using Replicat. Calculating ranges on the target side requires Replicat to
 read through the entire trail to find the data that meets each range specification.

二、實操

2.1 定位緩慢SQL

套路沒變，儘量快速一點。
SQL> select sql_id,count(*) from v$active_session_history where SAMPLE_TIME >sysdate-1 and SESSION_ID=1585 and SESSION_SERIAL#=79
 group by sql_id order by 2;

SQL_ID        COUNT(*)
------------- ----------
gtbj8txbkf9n5           1
1tvzus967pxky           4
d8n0wrf6fmrkz           4
3dbvkp2hd4f85           7
              29
43gz5209aq7wv          62
g68nmt0ww3xjm       85973

SQL> select * from table(dbms_xplan.display_cursor('g68nmt0ww3xjm'));

INSERT INTO "CC"."666"
("ID","1","2","3","4","5","S
END_WAY","SEND_VALUE","AC_CODE","AC_NAME","AC_TYPE","REPERTORY_ID","MECH
ANISM_CODE","ACCOUNT_ID","IS_PROVINCE","USER_ID","PHONE","PROVINCE_CODE"
,"ORG_NO","CONS_NO","RECORD_ST ······

觀察下SQL是否存在異常event null

SQL> select event,count(*) from v$active_session_history where SAMPLE_TIME >sysdate-1 and SESSION_ID=1585 and SESSION_SERIAL#=79 and sql_id='g68nmt0ww3xjm' group by event order by 2;

EVENT COUNT(*)
---------------------------------------------------------------- ----------
log file switch completion 1
SQL*Net more data from client 2
gc current multi block request 4
enq: FB - contention 4
gc current request 5
gc current grant congested 13
gc current grant 2-way 1045
1090
db file sequential read 83812
9 rows selected.

2.2 觀察表涉及的約束名稱,是否存在主鍵。

select owner,constraint_name,constraint_type,table_name from dba_constraints where owner='O' and table_name='I_LOW'

OWNER CONSTRAINT_NAME C TABLE_NAME

-------------------- ------------------------------

O O_PK P I_LOW O SYS_C0011517 C I_LOW
可以發現ID是表的主鍵列！！！

select * from dba_cons_columns where owner='O' and table_name='I_LOW'

CONSTRAINT_NAME TABLE_NAME COLUMN_NAME POSITION
-------------------- ------------------------------ ------------------------------ ------------------------------ ----------
 SYS_C0011517	I_LOW	ID
 O_PK           I_LOW	ID	1

2.3 將表拆分為6個程序！

GGSCI > stop rep_w
GGSCI > info rep_w
Log Read Checkpoint File /ogg/dirdat/666/fj000000082
2020-07-01 13:41:33.002883 RBA 771547003

>dblogin USERID OGG, PASSWORD cc
add checkpointtable ogg.chekpoint_rep_1
add checkpointtable ogg.chekpoint_rep_2
add checkpointtable ogg.chekpoint_rep_3
add checkpointtable ogg.chekpoint_rep_4
add checkpointtable ogg.chekpoint_rep_5

GGSCI >add rep rep_f1,exttrail /ogg/dirdat/666/fj checkpointtable ogg.chekpoint_rep_1
GGSCI >edit param rep_f1
replicat rep_f1
setenv (NLS_LANG=AMERICAN_AMERICA.UTF8)
USERID OGG, PASSWORDcc

REPORT AT 01:59
reportrollover at 02:00
DISCARDFILE ./dirrpt/rep_f1.dsc, APPEND, MEGABYTES 1024
DISCARDROLLOVER AT 02:30
GETUPDATEBEFORES
ALLOWDUPTARGETMAP
grouptransops 5000
batchsql opsperbatch 2000 opsperqueue 2000
-- HANDLECOLLISIONS
MAP O.I__W, TARGET O.I_W,filter(@range(1,6,ID)), RESOLVECONFLICT(UPDATEROWMISSING(DEFAULT, OVERWRITE));
GGSCI>alter replicat rep_f1,extseqno 82,extrba 771547003

以此類推， 主要就是加上filter(@range(1,6,column_name))  如下展示！  拆分後，OGG延遲00:00:00！！！ OK
MAP O.I__W, TARGET O.I_W,filter(@range(1,6,ID))
MAP O.I__W, TARGET O.I_W,filter(@range(2,6,ID))
MAP O.I__W, TARGET O.I_W,filter(@range(3,6,ID))
MAP O.I__W, TARGET O.I_W,filter(@range(4,6,ID))
MAP O.I__W, TARGET O.I_W,filter(@range(5,6,ID))
MAP O.I__W, TARGET O.I_W,filter(@range(6,6,ID))