db2 执行计划的解读

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db2exfmt o Table Operators                                             ITPUB个人空间*Y.T8? n r1Zb
db2exfmt     TBSCAN - Table Scan                                       ITPUB个人空间[~@PPL
db2exfmt     IXSCAN - Index Scan                                       ITPUB个人空间*wUS\L5m
db2exfmt     FETCH - Fetch from Table                                 ITPUB个人空间}r4|;@ CFUQ&{l
db2exfmt                                                               ITPUB个人空间/c9@W0H |'s.F5D
db2exfmt o Joins                                                       ITPUB个人空间;V4K5k1apb
db2exfmt     MSJOIN - Merge Scan Join
N*ppNKg0db2exfmt     NLJOIN - Nested Loop Join                                 ITPUB个人空间 mA{5P_'eC8i:S"T
db2exfmt     HSJOIN - Hash Join                                        ITPUB个人空间n%^ MfwIcNG
db2exfmt                                                               ITPUB个人空间T8}LKA'P"l+pL7x
db2exfmt o Aggregation                                                 ITPUB个人空间$h^*{$O,K9O;d
db2exfmt     GRPBY - Group By
Iu;LU,`O#t0M0db2exfmt     SUM    - Sum                                              ITPUB个人空间&F,A8Jj2y
db2exfmt     AVG    - Average                                          ITPUB个人空间+H"cx!o1I0H}r R
db2exfmt     MIN    - Minimum
+O5E`U#Z q]6X;gv0db2exfmt     MAX    - Maximun
6rPTlX*bu m&t0db2exfmt     etc.
+KY'w a8QZgYc0db2exfmt                                                               ITPUB个人空间S,kkw:J0b#b!aq
db2exfmt o Temp / Sort                                                 ITPUB个人空间a~:Xz:vDJ p
db2exfmt     TEMP   - Insert into temp table                           ITPUB个人空间eF ic/s0T!t
db2exfmt     SORT   - Sort                                             ITPUB个人空间k2N\P;z+Z
db2exfmt                                                               ITPUB个人空间qg NL:pG5C
db2exfmt o Special Operations                                          ITPUB个人空间V)yj1Bxfk
db2exfmt     IXAND - Index ANDing                                     ITPUB个人空间n$@%?sy7Uh i
db2exfmt     RIDSCA - Index ORing or List Prefetch
On@)S3{}!EBL0db2exfmt     IXA    - Star Schema Bitmap Indexing                      ITPUB个人空间D^HGY@Sz#T
db2exfmt     BTQ    - Broadcast Table Queue
lf A:xY#lU0db2exfmt     DTQ    - Directed Table Queue                             ITPUB个人空间$r5R:C6} l
db2exfmt     MBTQ   - Merge Broadcast Table Queue                      ITPUB个人空间/_Y/cuo3Q
db2exfmt     MDTQ   - Merge Directed Table Queue                       ITPUB个人空间%h^h"i(` LR
db2exfmt     LTQ    - Local Table Queue, for Intra-partition parallelism

+-------------------------------+-----------------------+-----------------------+
#fo&W!yw0| Join Strategy                 | Inner Table           | Outer Table           |
Up&XB/G0iY0+-------------------------------+-----------------------+-----------------------+ITPUB个人空间1ny/]%P+GO5?
| Collocated Join               | Temporary Table       | Temporary Table       |ITPUB个人空间:L{Cs-v,T+Y
+-------------------------------+-----------------------+-----------------------+
G{p%?7cn'^kV;a0| Directed Inner Join           | Temporary Table       | Hashed Table Queue    |
1f-{3W8F y3VeR0| Directed Outer Join           | Hashed Table Queue    | Temporary Table       |ITPUB个人空间+Xv$WQXY+D
| Directed Inner and Outer Join | Hashed Table Queue    | Hashed Table Queue    |
L1y?n/vU}}0+-------------------------------+-----------------------+-----------------------+
@3TA8[Fv+t8N!}0| Broadcast Inner Join          | Temporary Table       | Broadcast Table Queue |
5]\$C;P;^h @}0| Boradcast Outer Join          | Broadcast Table Queue | Temporary Table       |ITPUB个人空间 Slt0_6d)Y
+-------------------------------+-----------------------+-----------------------+

附:

BTQ	Broadcast Table Queue broadcasts data to several partitions.
DELETE	Deletes rows from a table.
DTQ	Directed Table Queue transfers data to a specific partition.
EISCAN	Scans a user-defined index to produce a reduced stream of rows.
FETCH	Fetches columns from a table using spe-cific record identifier.
FILTER	Represents the application of residual predicates.
GRPBY	Groups rows by common values of desig-nated columns or functions.
HSJOIN	Represents a hash join, where two or more tables are hashed on join columns.
INSERT	Inserts rows into a table.
IXAND	ANDs together the row identifiers (RIDs) from two or more index scans.
IXSCAN	Scans an index of a table with optional start/stop conditions, producing an ordered stream of rows.
LTQ	Local Table Queue. Transfers data between local agents.
LMTQ	Local Merge Table Queue. Merges data transferred between local agents.
MBTQ	Merging Broadcast Table Queue.
MDTQ	Merging Directed Table queue.
MSJOIN	Represents a merge join, where both outer and inner tables must be in join-predicate order.
NLJOIN	Represents a nested loop join that accesses an inner table once for each row of the outer table.
RETURN	Represents the return of data from the query to the user.
RIDSCAN	Scans a list of row identifiers (RIDs) obtained from one or more indexes.
RPD	For nonrelational wrappers, it shows the simulated SQL operation that the nonrela-tional wrapper will be asked to perform.
SHIP	Retrieves data from a remote database source. Used in federated systems.
SORT	Sorts rows in the order of specified col-umns, and optionally eliminates duplicate entries.
TBSCAN	Retrieves rows by reading all required data directly from the data pages.
TEMP	Stores data in a temporary table to be read back out (possibly multiple times).
TQUEUE	Transfers table data between agents.
UNION	Concatenates streams of rows from multi-ple tables.
UNIQUE	Eliminates rows with duplicate values, for specified columns.
UPDATE	Updates rows in a table.