AWS RDS 上 MySQL 通用查询日志的大小

Question

I'm trying to find the size of my general query log. I can't find out via the mysql interface, since it's stored via CSV engine (and it just shows 0 when queried):

show table status from mysql;

# Name, Engine, Version, Row_format, Rows, Avg_row_length, Data_length, Max_data_length, Index_length, Data_free, Auto_increment, Create_time, Update_time, Check_time, Collation, Checksum, Create_options, Comment

'general_log', 'CSV', '10', 'Dynamic', '1', '0', '0', '0', '0', '0', NULL, NULL, NULL, NULL, 'utf8_general_ci', NULL, '', 'General log'

I know there are at least 100k rows in there (mostly queries) by manually inspecting it via:

select * from mysql.general_log;

The thing is, I can't seem to find a way to access the log from AWS console side. From the management console, there is only the very general log (with the following info in it):

/rdsdbbin/mysql/bin/mysqld, Version: 5.6.23-log (MySQL Community Server (GPL)). started with: Tcp port: 3306 Unix socket: /tmp/mysql.sock

... more of the same

I can't get to the actual csv since I don't have control over the actual server.

Does anyone have a clever way of getting the table size? At worst I can count the length of each field and estimate via row counts?

Answer 1

What I ended up doing is querying the size from the MySQL console, and estimated the size based on column types.

DESCRIBE mysql.general_log;
SELECT COUNT(*) FROM mysql.general_log;

You'll see 6 cols, each with relatively fixed size, except for the two MEDIUM TEXT cols, which you'll have to estimate. But you'll be able to get a decent ball mark.

Answer 2

(Copied from https://bugs.mysql.com/bug.php?id=53929 )

You can add the following procedure, which will determine the exact size of a CSV table from a mysql console:

DELIMITER //
DROP PROCEDURE IF EXISTS checkcsv//
CREATE PROCEDURE checkcsv(IN databasename CHAR(200),IN tablename CHAR(200))
BEGIN
  SET SESSION group_concat_max_len=10*1024*1024; /* 10Mb buffer for CONCAT_WS */
  SELECT GROUP_CONCAT(COLUMN_NAME) INTO @columnames FROM INFORMATION_SCHEMA.COLUMNS WHERE (TABLE_SCHEMA = databasename AND TABLE_NAME = tablename);
  SET @get_colsizes_stmt = CONCAT("SELECT SUM(CHAR_LENGTH(REPLACE(REPLACE(REPLACE(CONCAT_WS(',',",@columnames,"),UNHEX('0A'),'nn'),UNHEX('22'),'nn'),UNHEX('5C'),'nn'))) INTO @total_length FROM ",databasename,".",tablename,";");
  PREPARE get_colsizes FROM @get_colsizes_stmt;
  EXECUTE get_colsizes;
  DEALLOCATE PREPARE get_colsizes;
  SET @get_count_stmt = CONCAT('SELECT COUNT(*) INTO @rowcount FROM ',databasename,'.',tablename,';');
  PREPARE get_count FROM @get_count_stmt;
  EXECUTE get_count;
  DEALLOCATE PREPARE get_count;
  SELECT 2*COUNT(COLUMN_NAME) INTO @non_numeric_cols_count FROM INFORMATION_SCHEMA.COLUMNS WHERE (TABLE_SCHEMA = databasename AND TABLE_NAME = tablename AND NUMERIC_SCALE IS NULL); /* Counting quotes */
  SET @total_size=@total_length+(@rowcount*@non_numeric_cols_count) /* Adding counted quotes */ +@rowcount /* one LineFeed per row */;
  SET @avg_row_length=@total_size/@rowcount;
  SET @output_stmt = CONCAT ("SELECT CONCAT('",databasename,"','.','",tablename,"') AS 'Table', ",@rowcount," AS 'Number Of Rows', ROUND(@avg_row_length) AS 'Average Row Length', ",ROUND(@total_size)," AS 'Total size' FROM ",databasename,".",tablename," LIMIT 1;");
  PREPARE outputr FROM @output_stmt;
  EXECUTE outputr;
  DEALLOCATE PREPARE outputr;
END;
//
DELIMITER ;
----- 

----- Usage Example: ----- 
mysql> CALL checkcsv("mysql","general_log");
+-------------------+----------------+--------------------+------------+
| Table             | Number Of Rows | Average Row Length | Total size |
+-------------------+----------------+--------------------+------------+
| mysql.general_log |             53 |                183 |       9673 |
+-------------------+----------------+--------------------+------------+
1 row in set (0.01 sec)

Query OK, 0 rows affected (0.06 sec)
-----