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What is the upper limit of records for MySQL database table. I'm wondering about autoincrement field. What would happen if I add milions of records? How to handle this kind of situations?
Thx!
The greatest value of an integer has little to do with the maximum number of rows you can store in a table.
It's true that if you use an int or bigint as your primary key, you can only have as many rows as the number of unique values in the data type of your primary key, but you don't have to make your primary key an integer, you could make it a CHAR(100). You could also declare the primary key over more than one column.
There are other constraints on table size besides number of rows. For instance you could use an operating system that has a file size limitation. Or you could have a 300GB hard drive that can store only 300 million rows if each row is 1KB in size.
The limits of database size is really high:
http://dev.mysql.com/doc/refman/5.1/en/source-configuration-options.html
The MyISAM storage engine supports 232 rows per table, but you can build MySQL with the --with-big-tables option to make it support up to 264 rows per table.
http://dev.mysql.com/doc/refman/5.1/en/innodb-restrictions.html
The InnoDB storage engine has an internal 6-byte row ID per table, so there are a maximum number of rows equal to 248 or 281,474,976,710,656.
An InnoDB tablespace also has a limit on table size of 64 terabytes. How many rows fits into this depends on the size of each row.
The 64TB limit assumes the default page size of 16KB. You can increase the page size, and therefore increase the tablespace up to 256TB. But I think you'd find other performance factors make this inadvisable long before you grow a table to that size.
mysql int types can do quite a few rows: http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html
unsigned int largest value is 4,294,967,295
unsigned bigint largest value is 18,446,744,073,709,551,615
I suggest, never delete data. Don't say if the tables is longer than 1000 truncate the end of the table. There needs to be real business logic in your plan like how long has this user been inactive. For example, if it is longer than 1 year then put them in a different table. You would have this happen weekly or monthly in a maintenance script in the middle of a slow time.
When you run into to many rows in your table then you should start sharding the tables or partitioning and put old data in old tables by year such as users_2011_jan, users_2011_feb or use numbers for the month. Then change your programming to work with this model. Maybe make a new table with less information to summarize the data in less columns and then only refer to the bigger partitioned tables when you need more information such as when the user is viewing their profile. All of this should be considered very carefully so in the future it isn't too expensive to re-factor. You could also put only the users which comes to your site all the time in one table and the users that never come in an archived set of tables.
In InnoDB, with a limit on table size of 64 terabytes and a MySQL row-size limit of 65,535 there can be 1,073,741,824 rows. That would be minimum number of records utilizing maximum row-size limit. However, more records can be added if the row size is smaller .
According to Scalability and Limits section in http://dev.mysql.com/doc/refman/5.6/en/features.html,
MySQL support for large databases. They use MySQL Server with databases that contain 50 million records. Some users use MySQL Server with 200,000 tables and about 5,000,000,000 rows.
Row Size Limits
The maximum row size for a given table is determined by several factors:
The internal representation of a MySQL table has a maximum row size
limit of 65,535 bytes, even if the storage engine is capable of
supporting larger rows. BLOB and TEXT columns only contribute 9 to 12
bytes toward the row size limit because their contents are stored
separately from the rest of the row.
The maximum row size for an InnoDB table, which applies to data
stored locally within a database page, is slightly less than half a page. For example, the maximum row size is slightly less than 8KB for the default 16KB InnoDB page size, which is defined by the innodb_page_size configuration option. “Limits on InnoDB Tables”.
If a row containing variable-length columns exceeds the InnoDB maximum row size, InnoDB selects variable-length columns for external off-page storage until the row fits within the InnoDB row size limit.
The amount of data stored locally for variable-length columns that are
stored off-page differs by row format. For more information, see
“InnoDB Row Storage and Row Formats”.
Different storage formats use different amounts of page header and trailer data, which affects the amount of storage available for rows.
Link http://dev.mysql.com/doc/refman/5.7/en/column-count-limit.html
Row Size Limits
The maximum row size for a given table is determined by several factors:
The internal representation of a MySQL table has a maximum row size limit of 65,535 bytes, even if the storage engine is capable of supporting larger rows. BLOB and TEXT columns only contribute 9 to 12 bytes toward the row size limit because their contents are stored separately from the rest of the row.
The maximum row size for an InnoDB table, which applies to data stored locally within a database page, is slightly less than half a page for 4KB, 8KB, 16KB, and 32KB innodb_page_size settings. For example, the maximum row size is slightly less than 8KB for the default 16KB InnoDB page size. For 64KB pages, the maximum row size is slightly less than 16KB. See Section 15.8.8, “Limits on InnoDB Tables”.
If a row containing variable-length columns exceeds the InnoDB maximum row size, InnoDB selects variable-length columns for external off-page storage until the row fits within the InnoDB row size limit. The amount of data stored locally for variable-length columns that are stored off-page differs by row format. For more information, see Section 15.11, “InnoDB Row Storage and Row Formats”.
Different storage formats use different amounts of page header and trailer data, which affects the amount of storage available for rows.
For information about InnoDB row formats, see Section 15.11, “InnoDB Row Storage and Row Formats”, and Section 15.8.3, “Physical Row Structure of InnoDB Tables”.
For information about MyISAM storage formats, see Section 16.2.3, “MyISAM Table Storage Formats”.
http://dev.mysql.com/doc/refman/5.7/en/innodb-restrictions.html
There is no limit. It only depends on your free memory and system maximum file size. But that doesn't mean you shouldn't take precautionary measure in tackling memory usage in your database. Always create a script that can delete rows that are out of use or that will keep total no of rows within a particular figure, say a thousand.
What are problems occur when mysql server table contains more than 120 columns ?
from a technical point of view without any consideration on the reasons for which you need 120 columns in a table mysql documentation 5.7 says:
Column Count Limits
MySQL has hard limit of 4096 columns per table, but the effective
maximum may be less for a given table.
https://dev.mysql.com/doc/refman/5.7/en/column-count-limit.html
This is bad practice to have 120 columns in a table better to split into multiple tables.
Since MYSQL is famous for relation database, So make relation based tables structure.
List of issues comes once your application become bigger.
Application gets slow (Since data fetching from table is slowly).
If your internet is slow, then you may not load the application page.
If huge amount of data is loaded at once due to the numbers of columns, then your server require more bandwidth.
Might you may not able you open in mobile, Since mobile better work with small amount of data.
https://dba.stackexchange.com/questions/3972/too-many-columns-in-mysql
There is a hard limit of 4096 columns per table, but the effective maximum may be less for a given table. The exact limit depends on several interacting factors.
Every table (regardless of storage engine) has a maximum row size of 65,535 bytes. Storage engines may place additional constraints on this limit, reducing the effective maximum row size.
The maximum row size constrains the number (and possibly size) of columns because the total length of all columns cannot exceed this size.
...
Individual storage engines might impose additional restrictions that limit table column count. Examples:
InnoDB permits up to 1000 columns.
I've searched for this subject on the site, and found some tips, but non of them is working for me.
In VB net I am making a table in MySQL (InnoDB), first I will make all the columns and then I fill them with data. But when I am trying to make a table with many columns, I get this error:
Row size to large. The maximum row size for the used table type, not counting BLOBs, is 8126. This includes storage overhead, check the manual. You have to change some columns to TEXT or BLOBs.
It is crashing when I want more then 196 columns.
I already tried the row format at compressed, but then my maximum is 186 columns (?!). The maximum amount of columns is 300 for my project. I've searched n the config of mySQL workbench 6.3, but can't find the solution. So currently my settings are standard by wizard creation. All the data in the table is TEXT.
What is the upper limit of records for MySQL database table. I'm wondering about autoincrement field. What would happen if I add milions of records? How to handle this kind of situations?
Thx!
The greatest value of an integer has little to do with the maximum number of rows you can store in a table.
It's true that if you use an int or bigint as your primary key, you can only have as many rows as the number of unique values in the data type of your primary key, but you don't have to make your primary key an integer, you could make it a CHAR(100). You could also declare the primary key over more than one column.
There are other constraints on table size besides number of rows. For instance you could use an operating system that has a file size limitation. Or you could have a 300GB hard drive that can store only 300 million rows if each row is 1KB in size.
The limits of database size is really high:
http://dev.mysql.com/doc/refman/5.1/en/source-configuration-options.html
The MyISAM storage engine supports 232 rows per table, but you can build MySQL with the --with-big-tables option to make it support up to 264 rows per table.
http://dev.mysql.com/doc/refman/5.1/en/innodb-restrictions.html
The InnoDB storage engine has an internal 6-byte row ID per table, so there are a maximum number of rows equal to 248 or 281,474,976,710,656.
An InnoDB tablespace also has a limit on table size of 64 terabytes. How many rows fits into this depends on the size of each row.
The 64TB limit assumes the default page size of 16KB. You can increase the page size, and therefore increase the tablespace up to 256TB. But I think you'd find other performance factors make this inadvisable long before you grow a table to that size.
mysql int types can do quite a few rows: http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html
unsigned int largest value is 4,294,967,295
unsigned bigint largest value is 18,446,744,073,709,551,615
I suggest, never delete data. Don't say if the tables is longer than 1000 truncate the end of the table. There needs to be real business logic in your plan like how long has this user been inactive. For example, if it is longer than 1 year then put them in a different table. You would have this happen weekly or monthly in a maintenance script in the middle of a slow time.
When you run into to many rows in your table then you should start sharding the tables or partitioning and put old data in old tables by year such as users_2011_jan, users_2011_feb or use numbers for the month. Then change your programming to work with this model. Maybe make a new table with less information to summarize the data in less columns and then only refer to the bigger partitioned tables when you need more information such as when the user is viewing their profile. All of this should be considered very carefully so in the future it isn't too expensive to re-factor. You could also put only the users which comes to your site all the time in one table and the users that never come in an archived set of tables.
In InnoDB, with a limit on table size of 64 terabytes and a MySQL row-size limit of 65,535 there can be 1,073,741,824 rows. That would be minimum number of records utilizing maximum row-size limit. However, more records can be added if the row size is smaller .
According to Scalability and Limits section in http://dev.mysql.com/doc/refman/5.6/en/features.html,
MySQL support for large databases. They use MySQL Server with databases that contain 50 million records. Some users use MySQL Server with 200,000 tables and about 5,000,000,000 rows.
Row Size Limits
The maximum row size for a given table is determined by several factors:
The internal representation of a MySQL table has a maximum row size
limit of 65,535 bytes, even if the storage engine is capable of
supporting larger rows. BLOB and TEXT columns only contribute 9 to 12
bytes toward the row size limit because their contents are stored
separately from the rest of the row.
The maximum row size for an InnoDB table, which applies to data
stored locally within a database page, is slightly less than half a page. For example, the maximum row size is slightly less than 8KB for the default 16KB InnoDB page size, which is defined by the innodb_page_size configuration option. “Limits on InnoDB Tables”.
If a row containing variable-length columns exceeds the InnoDB maximum row size, InnoDB selects variable-length columns for external off-page storage until the row fits within the InnoDB row size limit.
The amount of data stored locally for variable-length columns that are
stored off-page differs by row format. For more information, see
“InnoDB Row Storage and Row Formats”.
Different storage formats use different amounts of page header and trailer data, which affects the amount of storage available for rows.
Link http://dev.mysql.com/doc/refman/5.7/en/column-count-limit.html
Row Size Limits
The maximum row size for a given table is determined by several factors:
The internal representation of a MySQL table has a maximum row size limit of 65,535 bytes, even if the storage engine is capable of supporting larger rows. BLOB and TEXT columns only contribute 9 to 12 bytes toward the row size limit because their contents are stored separately from the rest of the row.
The maximum row size for an InnoDB table, which applies to data stored locally within a database page, is slightly less than half a page for 4KB, 8KB, 16KB, and 32KB innodb_page_size settings. For example, the maximum row size is slightly less than 8KB for the default 16KB InnoDB page size. For 64KB pages, the maximum row size is slightly less than 16KB. See Section 15.8.8, “Limits on InnoDB Tables”.
If a row containing variable-length columns exceeds the InnoDB maximum row size, InnoDB selects variable-length columns for external off-page storage until the row fits within the InnoDB row size limit. The amount of data stored locally for variable-length columns that are stored off-page differs by row format. For more information, see Section 15.11, “InnoDB Row Storage and Row Formats”.
Different storage formats use different amounts of page header and trailer data, which affects the amount of storage available for rows.
For information about InnoDB row formats, see Section 15.11, “InnoDB Row Storage and Row Formats”, and Section 15.8.3, “Physical Row Structure of InnoDB Tables”.
For information about MyISAM storage formats, see Section 16.2.3, “MyISAM Table Storage Formats”.
http://dev.mysql.com/doc/refman/5.7/en/innodb-restrictions.html
There is no limit. It only depends on your free memory and system maximum file size. But that doesn't mean you shouldn't take precautionary measure in tackling memory usage in your database. Always create a script that can delete rows that are out of use or that will keep total no of rows within a particular figure, say a thousand.
What are the maximum allowed number of columns in a query in access 2003?
255 I believe. You can check by going to Help > Specifications > Query within Access.
As a general rule, if you ever find yourself asking a question about the maximum hardcoded limit of a technology, it's time to step back and verify that you're taking the right approach. Perhaps a query against access that's pulling in hundreds or thousands of columns isn't the right approach.
From Access Help File
Thank you Ben
Number of enforced relationships: 32 per table minus the number of indexes that are on the table for fields or combinations of fields that are not involved in relationships
Number of tables in a query: 32
Number of fields in a recordset: 255
Recordset size: 1 gigabyte
Sort limit: 255 characters in one or more fields
Number of levels of nested queries: 50
Number of characters in a cell in the query design grid: 1,024
Number of characters for a parameter in a parameter query: 255
Number of ANDs in a WHERE or HAVING clause: 99
Number of characters in an SQL statement: approximately 64,000
Maximum numnber of column that you can add in ms access query is 255 but Let me tell me one thing :
In access you can make query in two ways
Create query in design view
Create query by using wizard.
For the first option you will have only a max of 16 columns to add in a query
but using the second option you can add upto 255 columns in your query.
:)