An interesting feature of InnoDB type tables
Just encountered an interesting feature of InnoDB type tables: calling the query
For example, in a table with a size of 28.5 MB and a number of rows of 390,000, it showed values in the range from 190,000 to 509,000.
After rustling in the manual found clarification:
The number of rows. Some storage engines, such as MyISAM, store the exact count. For other storage engines such as 40% to 50%. In such cases, use SELECT COUNT (*) to obtain an accurate count.
The peculiarity is unusual and, as for me, a bit strange, but this is not a bug.
')
Can someone explain why?
PS Please do not minus much, this is my first
upd: I have zero experience in writing articles, therefore objective criticism is accepted, incl. and to the "rows".
SHOW TABLE SATUS; shows inaccurate number of rows in the table, and the more rows, the greater the error. Details under the cut.For example, in a table with a size of 28.5 MB and a number of rows of 390,000, it showed values in the range from 190,000 to 509,000.
After rustling in the manual found clarification:
The number of rows. Some storage engines, such as MyISAM, store the exact count. For other storage engines such as 40% to 50%. In such cases, use SELECT COUNT (*) to obtain an accurate count.
The peculiarity is unusual and, as for me, a bit strange, but this is not a bug.
')
Can someone explain why?
PS Please do not minus much, this is my first
.comupd: I have zero experience in writing articles, therefore objective criticism is accepted, incl. and to the "rows".
Source: https://habr.com/ru/post/80578/
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