Neoview Query Guide (R2.3, R2.4, R2.5)

Data TypeToken DescriptionToken
textIndication of whether an optimization for returning data from DAM is
used. The value used is returned if this optimization is used.
fast_scan
textPresent only if partition name is specified in the statementpartition_name
expr(text)Columns used as the primary keykey_columns
expr(text)Any predicate that is not a key predicate evaluated by the executor in
DAM
executor_predicates
textPredicate expression specified on the partitioning key. Displayed only
if partitioning key differs from clustering key.
part_key_predicate
expr(text)Expression of the begin key predicate; same as the end key predicatebegin_key
expr(text)Expression of the end key predicate; same as the begin key predicateend_key
text
Present if MDAM is used for the scan. Value used
mdam
INDEX_SCAN Operator
The INDEX_SCAN operator scans the index related to the base table. The operator description
contains details about how a certain access path is scanned, such as lock_mode and scan_direction.
Index scans can be of two types:
• Access to the index structure only (index-only scan).
• Access to the index with a join to the base table.
An index row contains a primary key that includes the indexed columns from the base table.
The index row also includes the primary key of the related row in the base table, which is used
to locate the base table row, if required.
If all of the columns required for the query can be obtained form the index (index-only scan),
then only the INDEX_SCAN operator will appear in the query plan. Otherwise, the query plan
will show a nested join from the index to the base table, and the base table will be accessed with
the FILE_SCAN_UNIQUE operator using the primary key for the base table row.
The INDEX_SCAN operator has no child operators. The description field for this operator contains
Data TypeToken DescriptionToken
integerA sequential number assigned to the fragment. 0 is always master
executor and 1 is reserved for the Explain plan. Numbers 2 to n will be
ESP or DAM fragments.
fragment_id
integerThe fragment_id for the parent fragment of the current fragment. Value
is (none) for master executor.
parent_frag
textmaster, ESP, or DAMfragment_type
textIndicates whether an optimization for short, simple operations is used.
Value is used if this optimization is used.
olt_optimization
textIndicates for short, simple operations whether a further optimization
that reduces the physical size of the plan is used.
olt_opt_lean
text{full scan | subset scan | unique access} of {index
index-name(table-name)| table}table-name
scan_type
text
Value volatile is present only if the scan is to a volatile table.
object_type
textDirection in which table is scanned: forward or reversescan_direction
text
Present if MDAM is used for the scan. Value used
mdam
textThe lock mode specified: shared, exclusive, not specified, or unknownlock_mode
Operators and Description Fields 43