what is the max size of database used for AMR tool that we used to identify table/procedure that we can move in In-Memory OLTP?
A quick Google give this:
The recommended maximum size for memory-optimized tables is 256GB
Related
Currently we are using MySQL 5.6 and now upgrading to MySQL8. We have taken the db dump in MySQL5.6 and then reinstalled MySQL8, and now restoring the db dump. When we are doing it, we are facing the issue of row size for some tables:
the row size is 8135 which is greater than maximum allowed size (8126)
Compared couple of properties between MySQL5.6 and MySQL8, found that MySQL 8 has these bigger properties
innodb_log_file_size
innodb_log_buffer_size
max_allowed_packet
Since it is working fine on MySQL5.6, I was hoping that it should work fine with MySQL8 also. Please let me know what changes can be done here, without impacting anything.
ROW_FORMAT=COMPACT
If contain, remove it from your sql.
Try adding following line in your MySQL configuration file.
innodb_strict_mode = OFF
Go back to 5.6 and shrink some of your varchar/text columns. And/or use vertical partitioning. Having a big 'row size' is doing something 'wrong'. Please provide SHOW CREATE TABLE for further critique.
I have a table with huge amount of data and very frequently added rows.
If in future, table size limit reached then how to handle this problem? What is the maximum size of MySQL database table?
If in future, table size limit reached then how to handle this
problem?
You could use partitioning
https://dev.mysql.com/doc/refman/5.7/en/partitioning.html
What is the maximum size of MySQL database table?
The effective maximum table size for MySQL databases is usually
determined by operating system constraints on file sizes, not by MySQL
internal limits. For up-to-date information operating system file size
limits, refer to the documentation specific to your operating system.
source https://dev.mysql.com/doc/refman/5.7/en/table-size-limit.html
I was wondering if there's a way to decrease the opened files in mysql.
Details :
mysql 5.0.92
engine used : MyISAM
SHOW GLOBAL STATUS LIKE 'Opened_tables' : 150K
SHOW VARIABLES LIKE '%open%' :
open_files_limit 200000
table_open_cache 40000
Solutions tried :
restart server : it works the opened tables counter is 0 but this isn't a good solution from my pov since you will need a restart every week because the counter will increase fast
FLUSH TABLES : like the mysql doc said it should force all tables in use to close but this doesn't happen
So any thoughts on this matter?
Generally, many open tables are nothing to worry about. If you come close to OS limits, you can increase this limits in the kernel settings:
How do I change the number of open files limit in Linux?
MySQL opens tables for each session independently to have better concurrency.
The table_open_cache and max_connections system variables affect the maximum number of files the server keeps open. If you increase one or both of these values, you may run up against a limit imposed by your operating system on the per-process number of open file descriptors. Many operating systems permit you to increase the open-files limit, although the method varies widely from system to system.
In detail, this is explained here
http://dev.mysql.com/doc/refman/5.5/en/table-cache.html
EDIT
To verify your assumption you could decrease max_connections and table_open_cache temporarily by SET GLOBAL table_open_cache := newValue.
The value can be adjusted dynamically without a server restart.
Prior MySQL 5.1 this variable is called table_cache
What I was trying to tell, is, that decreasing this value will probably even have a negative impact on performance in terms of less possible concurrent reads (queue get's longer), instead you should try to increase the OS limit and increase max_open_files, but maybe I just don't see the point here
How many tables can be created in a mysql database ?
And how many columns can be created in a mysql table ?
How many rows can be inserted into a mysql table ?
How many tables can be created in a mysql database ?
MySQL has no limit on the number of databases. The underlying file system may have a limit on the number of tables. Individual storage engines may impose engine-specific constraints. InnoDB permits up to 4 billion tables.
And how many columns can be created in a mysql table ?
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.
How many rows can be inserted into a mysql table ?
The number of rows is limited by the maximum size allowed for a table. This is OS-dependent. You can impose a limit on the number of rows by setting MAX_ROWS at table creation time.
Reference: Limits in MySQL
It really depends on the operating system and version of MySQL. Generally the MySQL file size for tables can be: (5.0 Version)
Operating System File-size Limit
Win32 w/ FAT/FAT32 2GB/4GB
Win32 w/ NTFS 2TB (possibly larger)
Linux 2.2-Intel 32-bit 2GB (LFS: 4GB)
Linux 2.4+ 4TB(using ext3 file system)
Solaris 9/10 16TB
MacOS X w/ HFS+ 2TB
NetWare w/NSS file system 8TB
For more information check http://dev.mysql.com/doc/refman/5.0/en/table-size-limit.html
Unlimited.
4096 columns.
Number of row limit is unknown to me.
See for example http://dev.mysql.com/doc/refman/5.0/en/column-count-limit.html.
Hard cap 4096 columns, but my experience: try not to use VARCHAR, use TINYTEXT.
Otherwise, you will easily reach limit "65,535-byte row size limit" even though you have less than 50 columns in the table.
Maximum row size allowed is 65535 bytes
We are trying to put several Tb in to MySQL Cluster, unfortunately the index does not fit in to memory.
Are there way to overcome this limitations of mysql?
are there way in mysql process range operations in parallel?
My data has a 3D points: (id x y z idkey someblob) inside the MYisam with 128 partitions. The NDBCLuster was unable load the data due to memory limits.
indexing goes over idkey(this is pre calculated peano-hilbert key).The total row count is about 10^9.
Thanks Arman.
EDIT
my setup is 2 datanodes 2 mysqld one mdm.
8Gb RAM per ndb with 4 cores.
The whole system has 30Tb Raid6.
The system is linux Scientific LInux 6.0, the cluster is 7.1 compiled from source.
It sounds like MySQL is ill-suited for the task (sorry). I would check out Tokyo Tyrant, maybe MongoDB or any other distributed key-value storage system. There are also specialized commercial products.
MongoDB is able to swap out some of it's indexes to the HD. I guess your problem is that MySQL just can't do that (I'm not a MySQL-guy though).
Maybe you can try to modify your config.ini file.
DataMemory=15000M
IndexMemory=2560M
But if two values are too high, you will encounter this bug:
Unable to use due to bitmap pages missaligned!!
So I'm still trying to solve it. Good luck.
I faced the same issue when I was loading only DB tables' structure. Which means DataMemory or IndexMemory were not of help here.
Also the number of tables didn't reach the limit in MaxNoOfTables so it is not the issue as well.
The solution for me here was to increase the values for MaxNoOfOrderedIndexes and MaxNoOfUniqueHashIndexes which reflect the max number of indexes you can have in the cluster. So if there are many indexes in your DB try to increase those variables accordingly.
Of course, a rolling restart must be done after that change to take effect!