This is the syntax for managing resources or changing settings on a per-session basis.
Determines whether to leave a message in the Trace Log of the session.
You can use this message as a Bit Flag with the following values:
- 0x1: Parsing, Validation, Optimization.
- 0x2: It leaves the result of performing DDL.
That is, when the value of the corresponding flag is 2, only the DDL is logged, and when the flag is 3, the error and DDL are logged together.
Below is an example of changing the logging flag of the session and leaving error logging.
Sets the default format for Datetime data types for this session.
When the server is started, the property DEFAULT_DATE_FORMAT is set to the session attribute.
If the property of the property has not changed, the value of the session will also be "YYYY-MM-DD HH24: MI: SS mmm: uuu: nnn".
Use this command to modify the default format of a datetime datatype for a specific user, regardless of the system.
V$session has a default date format set for each session and can be checked. Below is an example of checking and changing the value of the session.
Decides whether to output the hidden column (_arrival_time) in the column represented by * when executing the select of the session.
When the server is started, the value of the global property SHOW_HIDDEN_COLS is set to 0 for the session attribute.
If you want to change the default behavior of your session, you can set this value to 1.
V$session has a SHOW_HIDDEN_COLS value set for each session.
Sets whether to send the session's Append error message to the client program.
Use the following values for the error message.
- 0 = Do not send an error message.
- 1 = Send an error message.
Below is an example of use.
Sets the size of the hash table used to perform the GROUP BY or Distinct operation of the session.
If this value is set too large, memory usage will be heavy for each Hash operation. If too small, Hash bucket conflict will occur and query performance may be degraded.
It is recommended to specify the number of whole groups * 1.5 to 3.0.
Specifies the maximum amount of memory that a single SQL statement in the session will use when performing GROUP BY, DISTINCT, ORDER BY operations.
If you try to allocate more memory than the maximum memory, the system cancels the execution of the SQL statement and treats it as an error.
In case of error, record the error code and error message in machbase.trc including the query.