An operator node represents an action that
is performed on data or on the output from a table or an index when
the access plan is executed.
An access plan graph might contain any of the following operator
nodes:
- BTBSCAN
- A BTBSCAN node indicates
an operation called a buffer table scan,
in which DB2® accesses
the rows in a buffer table. The BTBSCAN node is the defining node
for a buffer table scan construct.
- CORSUB
ACCESS
- A CORSUB ACCESS node represents access by a correlated
subquery.
- DELETE
- A DELETE node
indicates the deletion of selected rows from a table
or a deletable view. The DELETE node is the defining node of a delete
construct.
- DFETCH
- A DFETCH node
represents an operation called a direct fetch, in
which DB2 directly
accesses the rows in a table by using previously known ROWIDs.
The
DFETCH node is the defining node for a direct fetch construct.
- DIXSCAN
- A DIXSCAN node represents DOCID
index scan access, which returns
a RID according to the DOCID.
- EXCEPT
- The
EXCEPT node represents the EXCEPT operation.
An EXCEPT operation
returns the rows in the outer table but not in the inner table, with
redundant duplicate rows eliminated.
- EXCEPTA
- An EXCEPTA node represents an EXCEPT ALL operation.
An EXCEPT
ALL operation returns the rows in the outer table but not in the inner
table, with redundant duplicate rows retained.
- FETCH
- A FETCH node represents an operation in
which DB2 fetches
rows from a table using the RIDs from an IXSCAN or MIXSCAN.
- FFETCH
- An FFETCH node represents an
operation in which DB2 uses
a fact table index to fetch the fact table during a data manager pushdown
star join.
- FIXSCAN
- A FIXSCAN node
represents an operation called a fact table index
scan, in which DB2 scans
a fact table index during a data manager pushdown star join.
- HSSCAN
- An HSSCAN node represents an operation in which DB2 accesses
a row using a fully qualified key and without using a traditional
index. This access method employs a hashing technique to transform
the key to a physical location of the row.
- INLIST
- An INLIST node represents an operation in which DB2 accesses
an in-memory table that stores the IN-list elements.
- INSERT
- An INSERT node indicates the insertion
of rows into a table or
an insertable view. The INSERT node is the defining node of an insert
construct.
- INTERSECT
- An INTERSECT
node represents the INTERSECT operation.
An INTERSECT
operation returns the rows both in the outer table and the inner table,
with redundant duplicate rows eliminated. The INTERSECT node is the
defining node of an INTERSECT construct.
- INTERSECTA
- An INTERSECTA node represents the INTERSECT ALL operation.
An
INTERSECT ALL operation returns the rows both in the outer table and
the inner table, with redundant duplicate rows retained.
- IXAND
- An IXAND node represents an operation
in which DB2 returns
the intersection of two sorted ROWID lists. Only those ROWIDs that
exist in both ROWID lists are included in the output.
- IXOR
- An IXOR node represents an operation in
which DB2 returns
the union of two sorted ROWID lists. Any ROWID that exists in at least
one of the ROWID lists is included in the output. Duplicate ROWIDs
are removed from the output.
- IXSCAN
- An
IXSCAN node represents a single-index scan. The IXSCAN node
is the defining node for a single-index access construct.
- MERGE
- A MERGE node represents an operation in
which DB2 merges
multiple data streams into one data stream.
- MERGE
(statement)
- The MERGE (statement) node represents the MERGE
statement. It
combines the conditional UPDATE and INSERT operation on a target table
(or view) in a single statement.
A MERGE statement operation performs
the following actions with values from a set of source rows:
- Updates
rows that satisfy the search condition in the ON clause
in a target table
- Inserts rows from the source table that
do not satisfy the search
condition.
- MIXSCAN
- A
MIXSCAN node represents a multiple-index scan. The MIXSCAN node
is the defining node for a multiple-index access construct.
- PARTITION
- A PARTITION node represents
an operation in which DB2 separates
one data stream into multiple data streams.
- RGLIST
- A RGLIST node represents a range-list access, which is used to
simplify the processing of OR predicates. The RGLIST node is the defining
node for a range-list access construct.
- REPARTITION
- A repartition node represents an operation in which DB2 re-partitions
multiple input data streams into multiple output data streams.
- RID FETCH
- A RID FETCH node represents
RID fetch access, which is used to
access data by using the built-in RID function.
- SIXSCAN
- A SIXSCAN node indicates an operation called a
sparse index scan,
in which DB2 accesses
a sparse index. The SIXSCAN node is the defining node for a sparse
index scan construct.
- SORT
- A SORT node indicates an operation in which DB2 sorts
the rows from previous operations based on the sort keys. This operation
always produces a work file. The SORT node is the defining node for
a sort operation construct.
- SORTRID
- A
SORTRID node represents an operation in which DB2 sorts
the qualified index entries that result from an index scan based on
the ascending order of ROWIDs.
- TBSCAN
- A TBSCAN node indicates a table space scan on a table, a work
file, a materialized query table, or a pipe. A TBSCAN node is the
defining node for a table space scan construct.
- TRUNCATE
- A TRUNCATE node represents a TRUNCATE statement,
which deletes
all rows for either base tables or declared global temporary tables.
The
TRUNCATE statement deletes all rows for either base tables or declared
global temporary tables. The base table can be in a simple table space,
a segmented table space, a partitioned table space, or a universal
table space. If the table contains LOB or XML columns, the corresponding
table spaces and indexes are also truncated.
- UNION
- A UNION node represents the union of the results
from two SELECT
statements to form a single result table that contains no duplicate
rows. The UNION node is the defining node of a UNION construct.
- UNIONA
- A UNIONA node represents the
union of the results from two SELECT
statements to form a single result table that might contain duplicate
rows. The UNIONA node is the defining node of a UNION ALL construct.
- UPDATE
- An UPDATE node indicates the
updating of one or more columns of
the selected rows in a table or an updatable view. The UPDATE node
is the defining node of an update construct.
- WFSCAN
- WFSCAN node indicates an operation called a work file scan, in
which DB2 performs
a scan on a work file that is labeled as WORKFILE. The WFSCAN node
is the defining node for work file scan construct.
- XIXAND
- A XIXAND node represents an operation
for XML data in which DB2 returns
the intersection of two sorted DOCID lists. Only those DOCIDs that
exist in both DOCID lists are included in the output.
- XIXOR
- A XIXOR node represents an operation for
XML data in which DB2 returns
the union of two sorted DOCID lists. Any DOCID that exists in at least
one of the DOCID lists is included in the output. Duplicate DOCIDs
are removed from the output.
- XIXSCAN
- A
XIXSCAN node represents XML index scan access, which returns
the DOCID and NODEID pairs according the key value.