Session Variables¶

Each client connection to TajoMaster creates a unique session, and the client and TajoMaster uses the session until disconnect. A session provides session variables which are used for various configs per session.

tsql provides the meta command \set to manipulate session variables. Just \set command shows all session variables.

default> \set
'name1'='val1'
'name2'='val2'
'name3'='val3'
     ...

\set key val will set the session variable named key with the value val.

default> \set
'CURRENT_DATABASE'='default'

default> \set key1 val1

default> \set
'CURRENT_DATABASE'='default'
'key1'='val1'

Also, \unset key will unset the session variable named key.

Now, tajo provides the following session variables.

• DIST_QUERY_BROADCAST_JOIN_THRESHOLD
• DIST_QUERY_JOIN_TASK_VOLUME
• DIST_QUERY_SORT_TASK_VOLUME
• DIST_QUERY_GROUPBY_TASK_VOLUME
• DIST_QUERY_JOIN_PARTITION_VOLUME
• DIST_QUERY_GROUPBY_PARTITION_VOLUME
• DIST_QUERY_TABLE_PARTITION_VOLUME
• EXECUTOR_EXTERNAL_SORT_BUFFER_SIZE
• EXECUTOR_HASH_JOIN_SIZE_THRESHOLD
• EXECUTOR_INNER_HASH_JOIN_SIZE_THRESHOLD
• EXECUTOR_OUTER_HASH_JOIN_SIZE_THRESHOLD
• EXECUTOR_GROUPBY_INMEMORY_HASH_THRESHOLD
• MAX_OUTPUT_FILE_SIZE
• CODEGEN
• CLIENT_SESSION_EXPIRY_TIME
• CLI_MAX_COLUMN
• CLI_NULL_CHAR
• CLI_PRINT_PAUSE_NUM_RECORDS
• CLI_PRINT_PAUSE
• CLI_PRINT_ERROR_TRACE
• CLI_OUTPUT_FORMATTER_CLASS
• CLI_ERROR_STOP
• TIMEZONE
• DATE_ORDER
• TEXT_NULL
• DEBUG_ENABLED
• TEST_BROADCAST_JOIN_ENABLED
• TEST_JOIN_OPT_ENABLED
• TEST_FILTER_PUSHDOWN_ENABLED
• TEST_MIN_TASK_NUM
• BEHAVIOR_ARITHMETIC_ABORT
• RESULT_SET_FETCH_ROWNUM