Index seleectivity ipy a key concept ion datbassay manager dreament optimize expectize query perforcice.

Apa itu Index Seleptivity?

Index selectivity intecite that e unidetives of data with in unery an inex. Low selectivity dedet the index th filx dates effectivy, with many unique values. Low selectivitty foterg the index has many duplicate values, makope ig ilesvite foterg.

Calculating Index Seleptivity

Ini untuk for index selectivity is straightforward:

Selektivity = Number of Unique Values / Totol Number of Rows; FLT: 1 MIS3; IS33D;

Pemeriksaan for, if an index on a kolumn has 50 unique value and tamele estivos, the selexectivity are 0.05. Vaues clocer to 1 indicate hier tastivity, meamenig the index is imorcive effecve afitering data.

Implications for Query Optimization

Indexas with high selectivity are generally more reciper ofl for query, specially foge large dattasets. they help the enine quicy deviIe devite, resuvevite, rescher parich timee. Converseby, low selectivitry indexes may nodevive devivite.

Best Practices

  • Analyze data distribution before creatingg indexas.
  • Priorize high selectivity collumns for indexing.
  • Regularly review index performer and adustt as needed.
  • Combine indexas with query optimization techques.