The COUNT() function is an aggregate function that returns the number of rows in a table. Some storage engines, such as MyISAM, store the exact count. When I use the command line I get 841 > rows and in the administrator I get 853 rows for 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. 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. [28 Dec 2005 22:32] MySQL Verification Team Thank you for the bug report. The row count is only a â¦ 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: Sanjay Kaushik wrote: > I have the same problem which is making me > nervous. 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. It seems that if you issue a select statement on a "merged table" the following insert statement does not update the metadata table_rows. 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%. 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 The number of rows. TABLE_ROWS. 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. The query should collect data from table name , schema name from information.schema and row count should be taken from actual table. In such cases, use SELECT COUNT(*) to obtain an accurate count. 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 COUNT() function allows you to count all rows or only rows that match a specified condition.. MyISAM. So it seems the row count is being cached SOMEWHERE (I donât know where). Compare it to MyISAM. 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. The problem arise only for tables included in a merge table. 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. I agree with @RemusRusanu (+1 for his answer) SELECT COUNT(*) FROM mydb.mytable in InnoDB behaves like a transactional storage engine should. 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.
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