SORT_AREA

1.320 SORT_AREA_SIZE

SORT_AREA_SIZE specifies (in bytes) the maximum amount of memory Oracle will use for a sort.

Property	Description
Parameter type	Integer
Default value	`65536`
Modifiable	`ALTER SESSION`, `ALTER SYSTEM ... DEFERRED`
Modifiable in a PDB	Yes
Range of values	Minimum: the value equivalent of six database blocks Maximum: operating system-dependent
Basic	No

Note:

Oracle does not recommend using the SORT_AREA_SIZE parameter unless the instance is configured with the shared server option. Oracle recommends that you enable automatic sizing of SQL working areas by setting PGA_AGGREGATE_TARGET instead. SORT_AREA_SIZE is retained for backward compatibility.

After the sort is complete, but before the rows are returned, Oracle releases all of the memory allocated for the sort, except the amount specified by the SORT_AREA_RETAINED_SIZE parameter. After the last row is returned, Oracle releases the remainder of the memory.

Increasing SORT_AREA_SIZE size improves the efficiency of large sorts.

Each sort in a query can consume memory up to the amount specified by SORT_AREA_SIZE, and there can be multiple sorts in a query. Also, if a query is executed in parallel, each PQ slave can consume memory up to the amount specified by SORT_AREA_SIZE for each sort it does.

SORT_AREA_SIZE is also used for inserts and updates to bitmap indexes. Setting this value appropriately results in a bitmap segment being updated only once for each DML operation, even if more than one row in that segment changes.

Larger values of SORT_AREA_SIZE permit more sorts to be performed in memory. If more space is required to complete the sort than will fit into the memory provided, then temporary segments on disk are used to hold the intermediate sort runs.

The default is adequate for most OLTP operations. You might want to adjust this parameter for decision support systems, batch jobs, or large CREATE INDEX operations.