索引是提高數據庫查詢性能的有力武器。沒有索引,就好比圖書館沒有圖書標簽一樣,找一本書自己想要的書比登天還難。然而索引在使用的過程中,尤其是在批量的DML的情形下會產生相應的碎片,以及B樹高度會發生相應變化,因此可以對這些變化較大的索引進行重構以提高性能。N久以前Oracle建議我們定期重建那些高度為4,已刪除的索引條目至少占有現有索引條目總數的20%的這些表上的索引。但Oracle現在強烈建議不要定期重建索引。具體可以參考文章:Oracle 重建索引的必要性。盡管如此重建索引還是有必要的,只是不建議定期。本文給出了重建索引的腳本供大家參考。
1、重建索引shell腳本
robin@SZDB:~/dba_scripts/custom/bin> more rebuild_unbalanced_indices.sh # +-------------------------------------------------------+ # + Rebulid unblanced indices | # + Author : Leshami | # + Parameter : No | # +-------------------------------------------------------+ #!/bin/bash # -------------------- # Define variable # -------------------- if [ -f ~/.bash_profile ]; then . ~/.bash_profile fi DT=`date +%Y%m%d`; export DT RETENTION=1 LOG_DIR=/tmp LOG=${LOG_DIR}/rebuild_unbalanced_indices_${DT}.log [email protected] # ------------------------------------ # Loop all instance in current server # ------------------------------------- echo "Current date and time is : `/bin/date`">>${LOG} for db in `ps -ef | grep pmon | grep -v grep |grep -v asm |awk '{print $8}'|cut -c 10-` do echo "$db" export ORACLE_SID=$db echo "Current DB is $db" >>${LOG} echo "===============================================">>${LOG} $ORACLE_HOME/bin/sqlplus -S /nolog @/users/robin/dba_scripts/custom/sql/rebuild_unbalanced_indices.sql>>${LOG} done; echo "End of rebuilding index for all instance at : `/bin/date`">>${LOG} # ------------------------------------- # Check log file # ------------------------------------- status=`grep "ORA-" ${LOG}` if [ -z $status ];then mail -s "Succeeded rebuilding indices on `hostname` !!!" ${DBA} <${LOG} else mail -s "Failed rebuilding indices on `hostname` !!!" ${DBA} <${LOG} fi # ------------------------------------------------ # Removing files older than $RETENTION parameter # ------------------------------------------------ find ${LOG_DIR} -name "rebuild_unb*" -mtime +$RETENTION -exec rm {} \; exit
2、重建索引調用的SQL腳本
robin@SZDB:~/dba_scripts/custom/sql> more rebuild_unbalanced_indices.sql conn / as sysdba set serveroutput on; DECLARE resource_busy EXCEPTION; PRAGMA EXCEPTION_INIT (resource_busy, -54); c_max_trial CONSTANT PLS_INTEGER := 10; c_trial_interval CONSTANT PLS_INTEGER := 1; pmaxheight CONSTANT INTEGER := 3; pmaxleafsdeleted CONSTANT INTEGER := 20; CURSOR csrindexstats IS SELECT NAME, height, lf_rows AS leafrows, del_lf_rows AS leafrowsdeleted FROM index_stats; vindexstats csrindexstats%ROWTYPE; CURSOR csrglobalindexes IS SELECT owner,index_name, tablespace_name FROM dba_indexes WHERE partitioned = 'NO' AND owner IN ('GX_ADMIN'); CURSOR csrlocalindexes IS SELECT index_owner,index_name, partition_name, tablespace_name FROM dba_ind_partitions WHERE status = 'USABLE' AND index_owner IN ('GX_ADMIN'); trial PLS_INTEGER; vcount INTEGER := 0; BEGIN trial := 0; /* Global indexes */ FOR vindexrec IN csrglobalindexes LOOP EXECUTE IMMEDIATE 'analyze index ' || vindexrec.owner ||'.'|| vindexrec.index_name || ' validate structure'; OPEN csrindexstats; FETCH csrindexstats INTO vindexstats; IF csrindexstats%FOUND THEN IF (vindexstats.height > pmaxheight) OR ( vindexstats.leafrows > 0 AND vindexstats.leafrowsdeleted > 0 AND (vindexstats.leafrowsdeleted * 100 / vindexstats.leafrows) > pmaxleafsdeleted) THEN vcount := vcount + 1; DBMS_OUTPUT.PUT_LINE ( 'Rebuilding index ' || vindexrec.owner ||'.'|| vindexrec.index_name || '...'); <<alter_index>> BEGIN EXECUTE IMMEDIATE 'alter index ' || vindexrec.owner ||'.' || vindexrec.index_name || ' rebuild' || ' parallel nologging compute statistics' || ' tablespace ' || vindexrec.tablespace_name; EXCEPTION WHEN resource_busy OR TIMEOUT_ON_RESOURCE THEN DBMS_OUTPUT.PUT_LINE ( 'alter index - busy and wait for 1 sec'); DBMS_LOCK.sleep (c_trial_interval); IF trial <= c_max_trial THEN GOTO alter_index; ELSE DBMS_OUTPUT.PUT_LINE ( 'alter index busy and waited - quit after ' || TO_CHAR (c_max_trial) || ' trials'); RAISE; END IF; WHEN OTHERS THEN DBMS_OUTPUT.PUT_LINE ('alter index err ' || SQLERRM); RAISE; END; END IF; END IF; CLOSE csrindexstats; END LOOP; DBMS_OUTPUT.PUT_LINE ('Global indices rebuilt: ' || TO_CHAR (vcount)); vcount := 0; trial := 0; /* Local indexes */ FOR vindexrec IN csrlocalindexes LOOP EXECUTE IMMEDIATE 'analyze index ' || vindexrec.index_owner||'.' || vindexrec.index_name || ' partition (' || vindexrec.partition_name || ') validate structure'; OPEN csrindexstats; FETCH csrindexstats INTO vindexstats; IF csrindexstats%FOUND THEN IF (vindexstats.height > pmaxheight) OR ( vindexstats.leafrows > 0 AND vindexstats.leafrowsdeleted > 0 AND (vindexstats.leafrowsdeleted * 100 / vindexstats.leafrows) > pmaxleafsdeleted) THEN vcount := vcount + 1; DBMS_OUTPUT.PUT_LINE ( 'Rebuilding index ' || vindexrec.index_owner||'.'|| vindexrec.index_name || '...'); <<alter_partitioned_index>> BEGIN EXECUTE IMMEDIATE 'alter index ' || vindexrec.index_owner||'.' || vindexrec.index_name || ' rebuild' || ' partition ' || vindexrec.partition_name || ' parallel nologging compute statistics' || ' tablespace ' || vindexrec.tablespace_name; EXCEPTION WHEN resource_busy OR TIMEOUT_ON_RESOURCE THEN DBMS_OUTPUT.PUT_LINE ( 'alter partitioned index - busy and wait for 1 sec'); DBMS_LOCK.sleep (c_trial_interval); IF trial <= c_max_trial THEN GOTO alter_partitioned_index; ELSE DBMS_OUTPUT.PUT_LINE ( 'alter partitioned index busy and waited - quit after ' || TO_CHAR (c_max_trial) || ' trials'); RAISE; END IF; WHEN OTHERS THEN DBMS_OUTPUT.PUT_LINE ( 'alter partitioned index err ' || SQLERRM); RAISE; END; END IF; END IF; CLOSE csrindexstats; END LOOP; DBMS_OUTPUT.PUT_LINE ('Local indices rebuilt: ' || TO_CHAR (vcount)); END; / exit;
3、輸入日志樣本
Current date and time is : Sun Apr 20 02:00:02 HKT 2014 Current DB is SYBO2 =============================================== Rebuilding index GX_ADMIN.SYN_OUT_DATA_TBL_PK... Rebuilding index GX_ADMIN.IDX_TDBK_SPLNK_PARENT_REF... Rebuilding index GX_ADMIN.IDX_TDBK_SPLNK_CHILD_REF... Rebuilding index GX_ADMIN.PK_TRADE_BROKER_TBL... Rebuilding index GX_ADMIN.IDX_TDBK_INPUT_DATE... ................
4、後記
a、如果同一台服務器上有多個實例,且每個實例有相同的schema,此腳本會輪巡所有實例並根據analyze結果來rebuild。
a、大家應根據需要作相應調整,如腳本的路徑信息等。
b、需要修改相應的schema name。
d、可根據系統環境調整相應的並行度。
empno=100不存在的,改成有的數據了。
#!/bin/bash
result=$(sqlplus -s 'scott/tiger@dbname'<<EOF
spool test.txt
set pages 0
set feed off
set heading off;
set feedback off;
set verify off;
set linesize 1000;
SELECT * FROM scott.emp where empno=7369;
spool off
EOF
)
echo $result
~
~
~
~
~
~
~
~
~
"test.sh" 14L, 256C written
oracle@****:~> ./test.sh
7369 SMITH CLERK 7902 17-DEC-80 2240.06 20
oracle@****:~> more test.txt
7369 SMITH CLERK 7902 17-DEC-80 2240.06
20
empno=100不存在的,改成有的數據了。
#!/bin/bash
result=$(sqlplus -s 'scott/tiger@dbname'<<EOF
spool test.txt
set pages 0
set feed off
set heading off;
set feedback off;
set verify off;
set linesize 1000;
SELECT * FROM scott.emp where empno=7369;
spool off
EOF
)
echo $result
~
~
~
~
~
~
~
~
~
"test.sh" 14L, 256C written
oracle@****:~> ./test.sh
7369 SMITH CLERK 7902 17-DEC-80 2240.06 20
oracle@****:~> more test.txt
7369 SMITH CLERK 7902 17-DEC-80 2240.06
20