Operation
Option
Description
AND-EQUAL
Thes step will have two or more child steps each of which returns a set of ROWID's.The AND-EQUAL operation selects onlyl those ROWIDs that returned by all the child operations.
BITMAP
CONVERSION TO ROWIDS
Converts a bitmap from a bitmap index to a set of ROWIDs that can be used to retrieve the actual data.
BITMAP
CONVERSION FROM ROWIDS
Converts a set of ROWIDs into a bitmapped representation.
BITMAP
CONVERSION COUNT
Counts the number of rows represented by a bitmap.
BITMAP
INDEX SINGLE VALUE
Looks up the bitmap for a single key value in the index.
BITMAP
RANGE SCAN
Retrieves bitmaps for a key value range.
BITMAP
FULL SCAN
Performs a full scan of a bitmap index if there is no start or stop key.
BITMAP
MERGE
Merges several bitmaps resulting from a range scan into one bitmap.
BITMAP
MINUS
Subtracts bits of one bitmap from another. Row source is used for negated predicates. Can be used only if there are nonnegated predicates yielding a bitmap from which the subtraction can take place. An example appears in "Viewing Bitmap Indexes with EXPLAIN PLAN".
BITMAP
OR
Computes the bitwise OR of two bitmaps.
BITMAP
AND
Computes the bitwise AND of two bitmaps.
BITMAP
KEY ITERATION
Takes each row from a table row source and finds the corresponding bitmap from a bitmap index. This set of bitmaps are then merged into one bitmap in a following BITMAP MERGE operation.
CONNECT BY
Retrieves rows in hierarchical order for a query containing a CONNECT BY clause.
CONCATENATION
Operation accepting multiple sets of rows returning the union-all of the sets.
COUNT
Operation counting the number of rows selected from a table.
COUNT
STOPKEY
Count operation where the number of rows returned is limited by the ROWNUM expression in the WHERE clause.
DOMAIN INDEX
Retrieval of one or more rowids from a domain index. The options column contain information supplied by a user-defined domain index cost function, if any.
FILTER
Operation accepting a set of rows, eliminates some of them, and returns the rest.
FIRST ROW
Retrieval of only the first row selected by a query.
FOR UPDATE
Operation retrieving and locking the rows selected by a query containing a FOR UPDATE clause.
HASH JOIN
Operation joining two sets of rows and returning the result. This join method is useful for joining large data sets of data (DSS, Batch). The join condition is an efficient way of accessing the second table.
(These are join operations.)
CBO uses the smaller of the two tables/data sources to build a hash table on the join key in memory. Then it scans the larger table, probing the hash table to find the joined rows.
HASH JOIN
ANTI
Hash anti-join.
HASH JOIN
SEMI
Hash semi-join.
INDEX
UNIQUE SCAN
Retrieval of a single rowid from an index.
(These are access methods.)
INDEX
RANGE SCAN
Retrieval of one or more rowids from an index. Indexed values are scanned in ascending order.
INDEX
RANGE SCAN DESCENDING
Retrieval of one or more rowids from an index. Indexed values are scanned in descending order.
INDEX
FULL SCAN
Retrieval of all rowids from an index when there is no start or stop key. Indexed values are scanned in ascending order.
INDEX
FULL SCAN DESCENDING
Retrieval of all rowids from an index when there is no start or stop key. Indexed values are scanned in descending order.
INDEX
FAST FULL SCAN
Retrieval of all rowids (and column values) using multiblock reads. No sorting order can be defined. Compares to a full table scan on only the indexed columns. Only available with the cost based optimizer.
INDEX
SKIP SCAN
Retrieval of rowids from a concatenated index without using the leading column(s) in the index. Introduced in Oracle9i. Only available with the cost based optimizer.
INLIST ITERATOR
Iterates over the next operation in the plan for each value in the IN-list predicate.
INTERSECTION
Operation accepting two sets of rows and returning the intersection of the sets, eliminating duplicates.
MERGE JOIN
Operation accepting two sets of rows, each sorted by a specific value, combining each row from one set with the matching rows from the other, and returning the result.
(These are join operations.)
MERGE JOIN
OUTER
Merge join operation to perform an outer join statement.
MERGE JOIN
ANIT
Merge anti-join.
MERGE JOIN
SEMI
Merge semi-join.
MERGE JOIN
CARTESIAN
Can result from 1 or more of the tables not having any join conditions to any other tables in the statement. Can occur even with a join and it may not be flagged as CARTESIAN in the plan.
MINUS
Operation accepting two sets of rows and returning rows appearing in the first set but not in the second, eliminating duplicates.
NESTED LOOPS
Operation accepting two sets of rows, an outer set and an inner set. Oracle compares each row of the outer set with each row of the inner set, returning rows that satisfy a condition. This join method is useful for joining small subsets of data (OLTP). The join condition is an efficient way of accessing the second table.
(These are join operations.)
NESTED LOOPS
OUTER
Nested loops operation to perform an outer join statement.
PARTITION
SINGLE
Access one partition.
PARTITION
ITERATOR
Access many partitions (a subset).
PARTITION
ALL
Access all partitions.
PARTITION
INLIST
Similar to iterator, but based on an IN-list predicate.
PARTITION
INVALID
Indicates that the partition set to be accessed is empty.
Iterates over the next operation in the plan for each partition in the range given by the PARTITION_START and PARTITION_STOP columns. PARTITION describes partition boundaries applicable to a single partitioned object (table or index) or to a set of equi-partitioned objects (a partitioned table and its local indexes). The partition boundaries are provided by the values of PARTITION_START and PARTITION_STOP of the PARTITION.
REMOTE
Retrieval of data from a remote database.
SEQUENCE
Operation involving accessing values of a sequence.
SORT
AGGREGATE
Retrieval of a single row that is the result of applying a group function to a group of selected rows.
SORT
UNIQUE
Operation sorting a set of rows to eliminate duplicates.
SORT
GROUP BY
Operation sorting a set of rows into groups for a query with a GROUP BY clause.
SORT
JOIN
Operation sorting a set of rows before a merge-join.
SORT
ORDER BY
Operation sorting a set of rows for a query with an ORDER BY clause.
TABLE ACCESS
FULL
Retrieval of all rows from a table.
(These are access methods.)
TABLE ACCESS
SAMPLE
Retrieval of sampled rows from a table.
TABLE ACCESS
CLUSTER
Retrieval of rows from a table based on a value of an indexed cluster key.
TABLE ACCESS
HASH
Retrieval of rows from table based on hash cluster key value.
TABLE ACCESS
BY ROWID RANGE
Retrieval of rows from a table based on a rowid range.
TABLE ACCESS
SAMPLE BY ROWID RANGE
Retrieval of sampled rows from a table based on a rowid range.
TABLE ACCESS
BY USER ROWID
If the table rows are located using user-supplied rowids.
TABLE ACCESS
BY INDEX ROWID
If the table is nonpartitioned and rows are located using index(es).
TABLE ACCESS
BY GLOBAL INDEX ROWID
If the table is partitioned and rows are located using only global indexes.
TABLE ACCESS
BY LOCAL INDEX ROWID
If the table is partitioned and rows are located using one or more local indexes and possibly some global indexes.
Partition Boundaries -- The partition boundaries might have been computed by:
A previous PARTITION step, in which case the PARTITION_START and PARTITION_STOP column values replicate the values present in the PARTITION step, and the PARTITION_ID contains the ID of the PARTITION step. Possible values for PARTITION_START and PARTITION_STOP are NUMBER(n), KEY, INVALID.
The TABLE ACCESS or INDEX step itself, in which case the PARTITION_ID contains the ID of the step. Possible values for PARTITION_START and PARTITION_STOP are NUMBER(n), KEY, ROW REMOVE_LOCATION (TABLE ACCESS only), and INVALID.
UNION
Operation accepting two sets of rows and returns the union of the sets, eliminating duplicates.
VIEW
Operation performing a view's query and then returning the resulting rows to another operation.
OTHER_TAG Column Text
Tag Text
Meaning
Interpretation
blank
Serial execution.
SERIAL_FROM_REMOTE (S->R)
Serial from remote
Serial execution at a remote site.
SERIAL_TO_PARALLEL (S->P)
Serial to parallel
Serial execution; output of step is partitioned or broadcast to parallel execution servers.
PARALLEL_TO_PARALLEL (P->P)
Parallel to parallel
Parallel execution; output of step is repartitioned to second set of parallel execution servers.
PARALLEL_TO_SERIAL (P->S)
Parallel to serial
Parallel execution; output of step is returned to serial "query coordinator" process.
PARALLEL_COMBINED_WITH_PARENT (PWP)
Parallel combined with parent
Parallel execution; output of step goes to next step in same parallel process. No interprocess communication to parent.
PARALLEL_COMBINED_WITH_CHILD (PWC)
Parallel combined with child
Parallel execution; input of step comes from prior step in same parallel process. No interprocess communication from child.