The COUNT() function is an aggregate function that returns the number of rows in a table. The COUNT() function allows you to count all rows or only rows that match a specified condition.. The query should collect data from table name , schema name from information.schema and row count should be taken from actual table. Some storage engines, such as MyISAM, store the exact count. So it seems the row count is being cached SOMEWHERE (I donât know where). When I use the command line I get 841 > rows and in the administrator I get 853 rows for It seems that if you issue a select statement on a "merged table" the following insert statement does not update the metadata table_rows. The problem here is that MySQL returns NULL values for the row count when using a query like "show table status from `information_schema`;" We however have an alternate method of calculating the number of rows, which is already used for views. For other storage engines, such as InnoDB, this value is an approximation, and may vary from the actual value by as much as 40% to 50%. miguel@hegel:~/dbs/5.0> bin/mysql -uroot test Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Welcome to the MySQL monitor. mysql> CREATE TABLE t1 (c1 INT, db_row_id INT) ENGINE=INNODB; ERROR 1166 (42000): Incorrect column name 'db_row_id' SHOW TABLE STATUS does not provide accurate statistics for InnoDB tables except for the physical size reserved by the table. MyISAM. [28 Dec 2005 22:32] MySQL Verification Team Thank you for the bug report. Description: In some situation (as described below in "how to repeat") the table_rows column in the information_schema.tables table is not computed correctly. Bug #38909: CREATE_OPTIONS in information_schema produces wrong results: Submitted: 20 Aug 2008 10:51: Modified: 9 Dec 2008 0:15: Reporter: nadav wexler Summary: in this tutorial, you will learn how to use the MySQL COUNT() function to return the number rows in a table.. Introduction to the MySQL COUNT() function. Adding our count_rows function to the original query will get us row counts for each table: select table_schema, table_name, count_rows(table_schema, table_name) from information_schema.tables where table_schema not in ('pg_catalog', 'information_schema') and table_type='BASE TABLE' order by 3 desc. The number of rows. Compare it to MyISAM. Bug #9317: Wrong count for tables in INFORMATION_SCHEMA: Submitted: 21 Mar 2005 15:57: Modified: 31 Mar 2005 4:25: Reporter: Hakan KüçükyÄ±lmaz: Email Updates: The problem arise only for tables included in a merge table. TABLE_ROWS. If mydb.mytable is a MyISAM table, launching SELECT COUNT(*) FROM mydb.mytable; is just like running SELECT table_rows FROM information_schema.table WHERE table_schema = 'mydb' AND table_name = 'mytable';. The row count is only a â¦ I agree with @RemusRusanu (+1 for his answer) SELECT COUNT(*) FROM mydb.mytable in InnoDB behaves like a transactional storage engine should. In such cases, use SELECT COUNT(*) to obtain an accurate count. Sanjay Kaushik wrote: > I have the same problem which is making me > nervous. If you want a quick and dirty count of the number of rows in a InnoDB table, this seems to work: explain select count(*) from Table; The result is fast and will give you a ârowsâ count that should be within 10% of the number of rows in the Table.
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