global temporary table oracle 11g performance

tmp_cust_city b where b.customer_id=a.customer_id)Returns the case of excess 1, the following error is reported:SQL Code01427 00000 " Single-row subquery returns more than one row " // *cause: // *action:A comparatively simple approximation to irresponsible practice isSQL CodeUpdate customers A-- using the alias set city_name= (selectfromwhere b.customer_id=a.customer_id and rownum=1)How to understand the 01427 error, in a very complex multi-table co

to select the crosstab (intersection table) as the underlying table, which is the table referenced by the other table.Like what: The EMP table description describes the intersection of the location table and the category table.

Select the most efficient table name order (valid only in the rule-based optimizer)the parser for Oracle processes the table names in the FROM clause in a right-to-left order, so the table that is written in the FROM clause (the underlying table, driving tables) is processed

According to Oracle's documentation, the data pump in different ways to export imports, performance can be significantly different, this time just have the opportunity to test, migration table space, direct path, external table, and database chain export, import performance differences. This test external

necessary, and if multiple rows are deleted from the parent table, the child table is scanned once per row in the parent table. 2) Query the child table from the parent table: Consider the emp/dept example again. Using Deptno to query the EMP

Oracle performance optimization operation 18: whether to use full table scan or index Like all tips, the last trick will go back to the starting point. Finally, let's discuss whether to create an index, maybe it is faster to perform a full table scan. In most cases, full table