1.0

• RESULT-HOLDER—The time required on the data stores to iterate over the results, and serialize them over
the wire.
• ROUNDROBIN-ITERATION—The time required to merge results from an n-way merge.
• ROW-COUNT-ITERATION—The time spent returning rows specified in a FETCH NEXT clause. (See
OFFSET and FETCH FIRST Clauses on page 491.)
• SEQUENTIAL-ITERATION—The time required to merge and iterate the results on the query coordinator.
The following codes are shown only for data store members in a query plan:
• AGGREGATION—An aggregate operation such as SUM, AVG, MIN, or MAX.
• CONSTRAINTSCAN—The time spent on an index scan created from a table constraint.
• EXCEPT—An EXCEPT, EXCEPT ALL, or EXCEPT DISTINCT operation. See SQL Language Limitations
on page 653.
• FILTER—Indicates a predicate filtering operation.
• GLOBALINDEXSCAN—The time spent performing a global hash index scan (for example, for reference
checks).
• GROUPBY—Time spent grouping columns.
• HASHJOIN—The time spent on a hash join operation.
• HASHSCAN—Indicates the time spent scanning a generated hash table.
• HEAP—Time spent scanning GemFire regions.
• INDEXSCAN—If the query required a scan on an index, then this code indicates the time required for the
scan.
• INTERSECT—An INTERSECT, INTERSECT ALL, or INTERSECT DISTINCT operation. See SQL Language
Limitations on page 653.
• LOHASHJOIN—The time spend for a left or right hash outer join operation.
• LONLJOIN—The time spend for a left or right nested loop outer join operation.
• MERGEJOIN—The time spent on a merge join operation.
• NLJOIN—The time taken to perform a nested loop join (matching all of the left table rows with the right table
rows in a query). The individual seeks for the left and right table rows are timed separately and are listed in
sub-layers.
• PROJECT-FILTER—A predicate filtering operation that occurs while extracting columns (PROJECTION
operation).
• PROJECTION—The time spent to extract the selected columns from the base row of the table. This code can
appear multiple times for a query depending on how the engine processes the query.
• QUERY-RECEIVE—The time spent on the data store to deserialize the query request and process it on the
data store.
• RESULT-SEND—The net time taken to send the reply message. This value includes the RESULT-HOLDER
serialization time and the time for iterating each row on the data store.
• ROW-COUNT—Time spent processing results for the FETCH clause.
• ROWIDSCAN— The total time spent for index entries to fetch the base row from the table. This occurs when
the projection of the query is different from the index column.
• SET—Indicates a set operation (a UNION, UNION ALL, UNION DISTINCT, INTERSECT, INTERSECT
ALL, INTERSECT DISTINCT, EXCEPT, EXCEPT ALL, or EXCEPT DISTINCT operation). See SQL
Language Limitations on page 653.
• SCROLL-INSENSITIVE—A scroll insensitive cursor operation.
263
Evaluating Query Execution Plans and Query Statistics