Pular para o conteúdo principal

Index SKIP SCAN???

Index Skip Scan nada mais é que o "split" logico de um indice composto, ou seja, se sua clausula WHERE não tiver todos os campos do indice composto, ele é dividido em menores sub-indices

Exemplo:
--------
SQL> create table teste(a number,b number);

Table created.

SQL> begin
2 for i in 1..1000
3 loop
4 insert into teste values(i, 56);
5 end loop;
6 end;
7 /

PL/SQL procedure successfully completed.

SQL> create index idx_teste on teste(a,b);

Index created.

SQL> analyze table teste compute statistics;

Table analyzed.

SQL> explain plan for select /*+ index_ss(teste idx_teste) */ * from teste where b=56;

Explained.

SQL> start ?\rdbms\admin\utlxpls.sql

--------------------------------------------------------------------------------
| Operation | Name | Rows | Bytes| Cost | Pstart| Pstop |
--------------------------------------------------------------------------------
| SELECT STATEMENT | | 1K | 4K| 1001 | | |
| INDEX SKIP SCAN |teste_idx | 1K | 4K| 1001 | | |
--------------------------------------------------------------------------------

Comentários

Postagens mais visitadas deste blog

Webcenter Content - Cache Configuration for JdbcFileStore configuration

The configuration values below, control the temporarily cached files keep in FileCache table. FsCacheThreshold Specifies the maximum cache size, in megabytes (default=100) Once the threshold is met, Content Server starts deleting files that are older than the minimum age, as specified by the FsMinimumFileCacheAge parameter FsMaximumFileCacheAge The age at which files are deleted, expressed in days. The default is 365 days FsMinimumFileCacheAge The minimum age at which cached files can be deleted This parameter is used in conjunction with the FsCacheThreshold parameter to determine when to delete cached files FsCleanUpCacheDuringIndexing This parameter activates vault cache cleaning, while FsCacheThreshold, FsMaximumFileCacheAge and FsMinimumFileCacheAge are controling its behaviour.  Expect, when this is enabled on a system that currently has a large number of files in the FileCache table, the first cycle will take a long time to complete. How to Confi...

Assign Backup Policy for Boot and Block Volumes - OCI

To get Availability Domain oci iam availability-domain list  #!/bin/bash OCI_AD="hQsi:SA-SAOPAULO-1-AD-1" OCI_COMPARTMENT="ocid1.compartment.oc1..aaaaaaaavgyjpoffz5qliieawamjaksfb6juxejurtduclqjkvv66ookcxja" #Get Silver policy ocid funct_get_policy(){ OCI_POL_OCID=$(oci bv volume-backup-policy list | jq -r '.data[] | select(."display-name"|contains("silver"))' | jq -r '.id') } funct_boot_vol (){ #Create a file with all boot volume ocid oci bv boot-volume list --availability-domain ${OCI_AD} -c  ${OCI_COMPARTMENT} | jq -r '.data[].id' > boot-vol.txt while IFS="" read -r p || [ -n "$p" ] do   printf 'Seeting backup policy for %s\n' "$p"   oci bv volume-backup-policy-assignment create  --asset-id  $p  --policy-id ${OCI_POL_OCID} done < boot-vol.txt } funct_block_vol (){ #Create a file with all block volume ocid oci bv volume list  -c ${OCI_COMPARTMENT} | jq -r '.data[].id' ...

Logical Backup Using dbms_datapump

Sample scripts to make a logical backup using dbms_datapump -- BACKUP BY SCHEMA declare h1 NUMBER; begin h1 := dbms_datapump.open (operation => 'EXPORT', job_mode => 'SCHEMA', job_name => 'TESTE2', version => 'COMPATIBLE'); dbms_datapump.set_parallel(handle => h1, degree => 1); dbms_datapump.add_file(handle => h1, filename => 'BKP_SCHEMAS.LOG', directory => 'BKP_DATA_PUMP', filetype => 3); dbms_datapump.set_parameter(handle => h1, name => 'KEEP_MASTER', value => 0); dbms_datapump.metadata_filter(handle => h1, name => 'SCHEMA_EXPR', value => 'IN(''DENILSON'')'); dbms_datapump.add_file(handle => h1, filename => 'BKP_SCHEMAS.DMP', directory => 'BKP_DATA_PUMP', filetype => 1); dbms_datapump.set_parameter(handle => h1, name => 'INCLUDE_METADATA', value => 1); dbms_datapump.set_parameter(handle => h1, name ...