Does it depend on the number of values sets? Does it depend on the number of bytes in the INSERT statement?
You can insert infinitely large number of records using INSERT ... SELECT pattern, provided you have those records, or part of, in other tables.
But if you are hard-coding the values using INSERT ... VALUES pattern, then there is a limit on how large/long your statement is: max_allowed_packet which limits the length of SQL statements sent by the client to the database server, and it affects any types of queries and not only for INSERT statement.
Ideally, Mysql allow infinite number of rows creation in single insert (at once) but when a
MySQL client or the mysqld server receives a packet bigger than max_allowed_packet bytes, it issues a Packet too large error and closes the connection.
To view what the default value is for max_allowed_packet variable, execute the following command in in MySQL:
show variables like 'max_allowed_packet';
Standard MySQL installation has a default value of 1048576 bytes (1MB). This can be increased by setting it to a higher value for a session or connection.
This sets the value to 500MB for everyone (that's what GLOBAL means):
SET GLOBAL max_allowed_packet=524288000;
check your change in new terminal with new connection:
show variables like 'max_allowed_packet';
Now it should work without any error for infinite records insert. Thanks
Query is limited by max_allowed_packet in general.
You will hit the max_allowed_packet limit and
error: 1390 Prepared statement contains too many placeholders.
You can put 65535 placeholders in one sql.So if you have two columns in one row,you can insert 32767 rows in one sql.
Import of 50K+ Records in MySQL Gives General error: 1390 Prepared statement contains too many placeholders
refer to http://forums.mysql.com/read.php?20,161869, it's related with your mysql's configuration: max_allowed_packet, bulk_insert_buffer_size, key_buffer_size.
You can insert an infinite number of rows with one INSERT statement. For example, you could execute a stored procedure that has a loop executed a thousand times, each time running an INSERT query.
Or your INSERT could trip a trigger which itself performs an INSERT. Which trips another trigger. And so on.
No, it does not depend on the number of value sets. Nor does it depend on the number of bytes.
There is a limit to how deeply nested your parentheses may be, and a limit to how long your total statement is. Both of these are referenced, ironically, on thedailywtf.com . However, both of the means I mentioned above get around these limits.
I believe there's no defined number of rows you're limited to inserting per INSERT, but there may be some sort of maximum size for queries in general.
It is limited by max_allowed_packet.
You can specify by using:
mysqld --max_allowed_packet=32M
It is by default 16M.
You can also specify in my.cnf in /etc/mysql/
Related
I use delphixe4 to send query to MySQL Community 5.6.12 database using ADO.
In one of tables there is many varchar fields and I'm worry about sending insert query cause it will be too long !
Is there any Maximum Length for queries?
f1:='This is a test !';
ADOQuery1.SQL.ADD('INSERT INTO MyTable (field1,field2,field3,.....,field30)VALUES('+QuotedStr(f1)+','+....+QuotedStr(f30));
E.10.4. Limits on Table Column Count and Row Size
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.
So you do not have problems to add data on it (if you do not try to add more).
If Mysql accept this number of columms in a table, I think it is unrelated about Ado or other driver connector sql query.
I have a mySQL stored procedure that is executing a lot of inserts.
Since performance was being bad, I decided not to Insert in every loop rather than build a string for the INSERT and in the end of the procedure I would do just one big INSERT for all the values with a prepared statement.
The problem is that my statement will be bigger than a VARCHAR. It would have to be TEXT.
The question is: Can I do that? Or does a prepared statement have to be VARCHAR?
What is the maximum length of a prepared statement?
Use LOAD DATA. It's the option with the best performance when making a lot of inserts in mySQL, you can modify your input data as well.
Check about: http://dev.mysql.com/doc/refman/5.0/en/packet-too-large.html - this actual limit on single query
but your problem looks deeper, if you need to perform too many inserts, you need to prepare single insert statement, and in loop bind values to it and execute one by one
to speed up this process you will need to set autocommit to off, but then you will have next problem: http://dev.mysql.com/doc/refman/5.0/en/innodb-restrictions.html
InnoDB has a limit of 1023 concurrent transactions that have created undo records by modifying data.
and innodb_log_file_size
this both setting will limit your transaction size, so basically you need to add commit each Nth row (instead of each 1 row), Nth is better to determine programmatic
UPDATE: check comment from #BillKarwin - basically we can say that there is no limit on transaction size
We all know that it's better to use multiple inserts in ONE query than to run MULTIPLE queries. But, I don't know upto how many these multiple extended values does Mysql support? I searched over net but didn't find the correct answer. I'm just curious to know this.
Example,
INSERT INTO tbl_name VALUES(1, 'John Doe'), (2, 'Peter England'), ....
I remember when I was using some MVC framework where it was trying to fire hundreds/thousands of inserts in one query, I used to get some sort of error message like Mysql server has gone away.
The limit for multiple inserts, like the one you are talking about would be bound by the packet limit.
See: http://dev.mysql.com/doc/refman/5.1/en/packet-too-large.html
This will affect all query types, and not just insert.
To add a little more context, the error you spoke of MySQL server has gone away would be a result of exceeding the packet limit. A quote from the page:
You can also get these errors if you send a query to the server that
is incorrect or too large. If mysqld receives a packet that is too
large or out of order, it assumes that something has gone wrong with
the client and closes the connection. If you need big queries (for
example, if you are working with big BLOB columns), you can increase
the query limit by setting the server's max_allowed_packet variable,
which has a default value of 1MB. You may also need to increase the
maximum packet size on the client end. More information on setting the
packet size is given in Section C.5.2.10, “Packet too large”.
Your query's ultimate length limit is set by the max_allowed_packet setting - if you exceed that, the query gets truncated and almost certainly becomes invalid.
While doing a multi-value insert is more efficient, don't go overboard and try to do thousands of value sets. Try splitting it up so you're only doing a few hundred at most, and definitely make sure that the query string's length doesn't go near max_allowed_packet.
I want to find maximum number of data user can enter into the mysql table using insert query?
is it depend on the max_allowed_packet?
If yes, can we update it? and what is the max value to set it?
If no, is it depend on some other constants of mysql?
Yes, it does, the INSERT query should fit into one packet.
From the docs:
The protocol limit for max_allowed_packet is 1GB. The value should be a multiple of 1024; nonmultiples are rounded down to the nearest multiple.
To set it, use:
SET GLOBAL max_allowed_packet=1073741824;
I log into the (RDS) mysql server with the console client in two terminals, use the same database (not that that should matter), and run the query show status like 'created%' in each. They show a consistent number - no matter how many times I make the query, the answer doesn't change.
But they disagree with each other. Moreover,any time I use a different database, that query gives a different response, though that variable is supposed to be for the whole server.
The MySQL page gives this explanation for the variable:
The number of internal temporary tables created by the server while executing statements.
You can compare the number of internal on-disk temporary tables created to the total number of internal temporary tables created by comparing the values of the Created_tmp_disk_tables and Created_tmp_tables variables.
Can anybody explain why this would be happening? I can't understand how that variable could decrease at all, but the two sessions giving different numbers has me extra-stumped.
According to the manual at http://dev.mysql.com/doc/refman/5.0/en/server-status-variables.html you can request this specific status information both per session as well as globally.
Can you give us the output of
SHOW GLOBAL STATUS LIKE ...
and
SHOW SESSION STATUS LIKE ...