## How do you gather stats in index?

Index statistics can be gathered explicitly using the GATHER_INDEX_STATS procedure. EXEC DBMS_STATS. gather_index_stats(‘SCOTT’, ‘EMPLOYEES_PK’); EXEC DBMS_STATS. gather_index_stats(‘SCOTT’, ‘EMPLOYEES_PK’, estimate_percent => 15);

## How do you gather stats in Oracle?

AUTO_SAMPLE_SIZE); To estimate statistics, Oracle selects a random sample of data. You can specify the sampling percentage (Oracle Corporation recommends using DBMS_STATS ….Table 3-1 Statistics Gathering Procedures in the DBMS_STATS Package.

Procedure | Collects |
---|---|

GATHER_TABLE_STATS | Table, column, and index statistics |

**Does gather stats Rebuild index?**

The difference is, gathering statistics refreshes the metadata about the current index whereas dropping and re-creating the index is, er, dropping and re-creating the index.

### Do we need to gather stats after index creation Oracle?

There’s no need to gather statistics for empty objects; dynamic sampling will work just as quickly as reading stats from the data dictionary.

### Why do we gather stats in Oracle?

You must gather statistics on a regular basis to provide the optimizer with information about schema objects. New statistics should be gathered after a schema object’s data or structure are modified in ways that make the previous statistics inaccurate.

**How do you collect table statistics?**

begin DBMS_STATS. GATHER_TABLE_STATS(‘owner’, ‘table_name’, estimate_percent=>50, block_sample=>TRUE, degree=>4) ; end ; These statements collect statistics on all the objects associated with table_name, including the table columns and any indexes (b-tree, bitmap, or Text domain) associated with the table.

## What is a stale index?

Statistics are likely to be stale if the number of distinct values in an index has changed significantly. This can happen often or rarely, depending on the nature of the column being indexed. You can refresh cardinality statistics by calling the procedure SYSCS_UTIL.

## Why do we need to gather stats in Oracle?

**What is analyze index in Oracle?**

When you use this command, Oracle calculates information about the B-tree depth and the distribution of leaf and branch blocks. Perhaps most importantly, it calculates the number of distinct rows in the index; the more distinct rows there are, the more likely that a given index lookup will result in very few rows.