v8里,LOAD可以对表做select了
ALLOW READ ACCESS
Load will lock the target table in a share mode. The table state will be set to both LOAD IN PROGRESS and READ ACCESS. Readers can access the non-delta portion of the data while the table is being load. In other words, data that existed before the start of the load will be accessible by readers to the table, data that is being loaded is not available until the load is complete. LOAD TERMINATE or LOAD RESTART of an ALLOW READ ACCESS load can use this option; LOAD TERMINATE or LOAD RESTART of an ALLOW NO ACCESS load cannot use this option. Furthermore, this option is not valid if the indexes on the target table are marked as requiring a rebuild.
When there are constraints on the table, the table state will be set to CHECK PENDING as well as LOAD IN PROGRESS, and READ ACCESS. At the end of the load the table state LOAD IN PROGRESS state will be removed but the table states CHECK PENDING and READ ACCESS will remain. The SET INTEGRITY statement must be used to take the table out of CHECK PENDING. While the table is in CHECK PENDING and READ ACCESS, the non-delta portion of the data is still accessible to readers, the new (delta) portion of the data will remain inaccessible until the SET INTEGRITY statement has completed. A user can perform multiple loads on the same table without issuing a SET INTEGRITY statement. Only the original (checked) data will remain visible, however, until the SET INTEGRITY statement is issued.
ALLOW READ ACCESS also supports the following modifiers:
USE tablespace-name
If the indexes are being rebuilt, a shadow copy of the index is built in table space tablespace-name and copied over to the original table space at the end of the load during an INDEX COPY PHASE. Only system temporary table spaces can be used with this option. If not specified then the shadow index will be created in the same table space as the index object. If the shadow copy is created in the same table space as the index object, the copy of the shadow index object over the old index object is instantaneous. If the shadow copy is in a different table space from the index object a physical copy is performed. This could involve considerable I/O and time. The copy happens while the table is offline at the end of a load during the INDEX COPY PHASE.
Without this option the shadow index is built in the same table space as the original. Since both the original index and shadow index by default reside in the same table space simultaneously, there might be insufficient space to hold both indexes within one table space. Using this option ensures that you retain enough table space for the indexes.
This option is ignored if the user does not specify INDEXING MODE REBUILD or INDEXING MODE AUTOSELECT. This option will also be ignored if INDEXING MODE AUTOSELECT is chosen and load chooses to incrementally update the index.
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