CREATE INDEX index_name ON TABLE_NAME ( COLUMN_NAME ); PostgreSQL 索引==>https://www.runoob.com/postgresql/postgresql-index.html 查看是否走索引 not in 不走, 当in的个数很小的时候走, 多了也不走 explain analyze SELECT * FROM "tablea" where id not in ('23'); 索引知识 我对PostgreSQL ...
postgres=# \d t Table "public.t" Column | Type | Collation | Nullable | Default ---+---+---+---+--- id | integer | | not null | mc | text | | | Indexes: "t_pkey" PRIMARY KEY, btree (id) postgres=# CREATE UNIQUE INDEX CONCURRENTLY t_id_temp_idx ON t (id); CREATE ...
If duplicate values exist in the column(s) on which the constraint was defined during UNIQUE constraint creation, the UNIQUE constraint creation fails, returning an error message.UNIQUE constraints in PostgreSQL will accept multiple NULL values (similar to Oracle). UNIQUE co...
ORA-00218: block size of control file ” does not match DB_BLOCK_SIZE () ORA-00219: required control file size ( logical blocks) exceeds maximum allowable size ( logical blocks) ORA-00220: control file not mounted by first instance, check alert log for more info ORA-00221: error on writ...
In this case disable this directive and the BLOB columns will not be included into data export. Take care that the target bytea column do not have a NOT NULL constraint. ENABLE_CLOB_EXPORT Same behavior as ENABLE_BLOB_EXPORT but for CLOB. DATA_EXPORT_ORDER By default data export order ...
This could be a problem if your column is defined with NOT NULL constraint. If you can not remove the constraint, use this directive to set an arbitral date that will be used instead. You can also use -INFINITY if you don't want to use a fake date. INDEXES_SUFFIX Add the given ...
PostgreSQL does not like select distinct a, b, c, label from rhnchannel order by upper(label) We used subselect. rownum Oracle has a special pseudocolumnrownumwhich can be used to limit resultset, similar to PostgreSQL'sLIMIT. We've changed the logic. ...
WHERE rownum < 5;Inst Startup Begin snap End Snap flush elapsed Err# --- --- -...
- 跟踪:Data Pump Worker 跟踪显示“SELECT NVL((SELECT /*+ NESTED_TABLE_GET_REFS */ :”SYS_B_0″ FROM … WHERE ROWNUM = :”SYS_B_1″), :”SYS_B_2″) FROM DUAL”的 elapsed fetch 时间值非常高 - 备注:针对此缺陷的修正只能作为Bug:5481520“Wrong results with ROWNUM and bind peeking”...
-Bug:4513695- Poor performance for SELECT with ROWNUM=1 with literal replacement - Bug 5095025 – Export Data Pump runs out of memory (ORA-4030) when exporting many schema’s -Bug:5464834- Export Data Pump runs out of memory (ORA-4030) when many tables are involved ...