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Support parallel aggregation.

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Parallel workers can now partially aggregate the data and pass the
transition values back to the leader, which can combine the partial
results to produce the final answer.

David Rowley, based on earlier work by Haribabu Kommi.  Reviewed by
Álvaro Herrera, Tomas Vondra, Amit Kapila, James Sewell, and me.
This commit is contained in:
Robert Haas
2016-03-21 09:20:53 -04:00
parent 7fa0064092
commit e06a38965b
23 changed files with 910 additions and 82 deletions
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11
src/include/nodes/primnodes.h
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@@ -255,12 +255,21 @@ typedef struct Param
* DISTINCT is not supported in this case, so aggdistinct will be NIL.
* The direct arguments appear in aggdirectargs (as a list of plain
* expressions, not TargetEntry nodes).
*
* 'aggtype' and 'aggoutputtype' are the same except when we're performing
* partal aggregation; in that case, we output transition states. Nothing
* interesting happens in the Aggref itself, but we must set the output data
* type to whatever type is used for transition values.
*
* Note: If you are adding fields here you may also need to add a comparison
* in search_indexed_tlist_for_partial_aggref()
*/
typedef struct Aggref
{
Expr xpr;
Oid aggfnoid; /* pg_proc Oid of the aggregate */
Oid aggtype; /* type Oid of result of the aggregate */
Oid aggtype; /* type Oid of final result of the aggregate */
Oid aggoutputtype; /* type Oid of result of this aggregate */
Oid aggcollid; /* OID of collation of result */
Oid inputcollid; /* OID of collation that function should use */
List *aggdirectargs; /* direct arguments, if an ordered-set agg */