无法通过相等运算符比较coulmn中的NULL值[重复]我们需要理解NULL在PostgreSQL中意味着没有值。它不等于0...
无法通过相等运算符比较coulmn中的NULL值[重复]我们需要理解NULL在PostgreSQL中意味着没有值。它不等于0...
入参BufferAccessStrategy代表当前的替换策略,如果是NULL的话,表示默认替换策略。为了保证我们返回的页面别人不能在我们之前增加引用计数,返回的buffer中,持有buffer header的spinlock(BM_LOCKED)。1.如果策略不为空的话,调用GetBufferFromRing尝试从环形缓冲区中获取,如果成功获取到一个buffer,返回。2.如果bgwprocno不为...
'<%u%%%d> ' #log_lock_waits = off # log lock waits >= deadlock_timeout #log_statement = 'none' # none, ddl, mod, all #log_temp_files = -1 # log temporary files equal or larger # than the specified size in kilobytes; # -1 disables, 0 logs all temp files log_timezone = ...
PreviouslyNULLvalues were always indexed as distinct values, but this can now be changed by creating constraints and indexes usingUNIQUE NULLS NOT DISTINCT." Two styles ofUNIQUE To take a look at what this change does, we create two tables. Thenull_old_styletable has a 2-columnUNIQUEconstraint...
However, if not told * to wait for the checkpoint to occur, we consider failure to send the * signal to be nonfatal and merely LOG it. The checkpointer should see * the request when it does start, with or without getting a signal. */ //给checkpoint进程发送信号,可能checkpointer还没...
Support guidelines I've read the support guidelines I've found a bug and checked that ... ... the documentation does not mention anything about my problem ... there are no open or closed issues that are related to my problem ... it's def...
Other PL/pgSQL statements do not change the state of FOUND. Note in particular that EXECUTE changes the output of GET DIAGNOSTICS, but does not change FOUND. FOUND is a local variable within each PL/pgSQL function; any changes to it affect only the current function. ...
SELECT*FROMassert.is_equal(actual, expected)INTOmessage,result; TRUNCATETABLEtest_values; -- Check if test failed IF result = false THEN RETURN message; ENDIF; -- Otherwise test passed SELECTassert.ok('Test passed.')INTOmessage; RETURN message; ...
ifexists - if true, error is not thrown when subscription does not exist, default is false pglogical.alter_node_add_interface(node_name name, interface_name name, dsn text) Adds additional interface to a node. When node is created, the interface for it is also created with the dsn specifi...