netezza, ?ERROR: GROOM VERSIONS must be run on *** 的处理

对netezza数据库的groom脚本执行遇到下面的错误：
ERROR:  GROOM VERSIONS must be run on T_DDW_F00_OP_TEST_DAY before any other GROOM operation


什么是groom verions?

链接：
When you use alter table to add or drop columns, what actually happens is that NPS creates a new version of the table and creates a view which performs a UNION ALL between the old and new tables (making it appear as a single table).  The GROOM VERSIONS command combines all of the versions back  into a single table.  GROOM VERSIONS should be used reasonably soon after using alter table as there is a performance cost for using the UNION ALL view instead of having all of the data exist in a single table.  As you have already observed,  you cannot use the normal GROOM command on a table until the versions have been combined back into a single table.

具体执行命令如下：

TEST(ADMIN)=> select TABLENAME, RELVERSION from _v_table where OBJTYPE='TABLE' and RELVERSION<>0;
              TABLENAME | RELVERSION
-------------------------------------+------------
 X27_REPORT | 3
(1 rows)

TEST(ADMIN)=>
TEST(ADMIN)=>
TEST(ADMIN)=>
TEST(ADMIN)=> groom table X27_REPORT versions;
NOTICE: Groom processed 37 pages; purged 141 records; scan size shrunk by 28 pages; table size shrunk by 28 extents.
GROOM VERSIONS
TEST(ADMIN)=> groom table X27_REPORT records ready;
NOTICE: Groom processed 16 pages; purged 0 records; scan size unchanged; table size unchanged.
GROOM RECORDS READY
TEST(ADMIN)=>
TEST(ADMIN)=> select TABLENAME, RELVERSION from _v_table where OBJTYPE='TABLE' and RELVERSION<>0;