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Trimming copy/delete mysql table rows using Trigger

I am using Freeradius AAA server on Ubuntu 18 server which uses mySQL ver 5.7.27 as DB to store entries. INNODB is being used. It have a table called radacct which stores users accounting /session ...
0
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0answers
19 views

Mysql 8.0.16 crash due to informatiin_schema.Keywords table

How to resolve issue of mysql 8.0.16 crash?mysql 8.0.16 crash many times and shown server logs due to invalid argument.and in error log query is select WORD from information_schema.KEYWORDS. how to ...
1
vote
1answer
156 views

Calculating disk usage with INFORMATION_SCHEMA.TABLE versus file system?

MySQL's database size can be calculated with SELECT table_schema AS db_name, SUM(data_length + index_length) AS size FROM INFORMATION_SCHEMA.TABLES WHERE table_schema != 'INFORMATION_SCHEMA' GROUP BY ...
2
votes
2answers
133 views

When does MySQL begin to start sending data to a client?

I am working on MySQL 5.7 with the default configuration of InnoDB storage engine. I have two questions each for a different scenario and need to know the internal working on how MySQL sends data to ...
0
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2answers
330 views

How to understand Composite Primary Key when it comes to storage (in Mysql)?

I can image how rows will be arranged in a single database page as primary key order (example an auto-increment key) after reading this post. But I wonder how it will in the case of composite primary ...
0
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2answers
117 views

No 'Copying to tmp table' state in profiling a mysql query

I have a table with 100k rows CREATE TABLE `small_table` ( `pk` int(11) NOT NULL AUTO_INCREMENT, `varc` varchar(255) DEFAULT NULL, `txt` text, PRIMARY KEY (`pk`) ) ENGINE=InnoDB ...
1
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1answer
62 views

How are page splits determined internally in MySQL?

Going through this answer for a stack-overflow question, I found a fact that In The physical structure of InnoDB index pages I describe the Last Insert Position, Page Direction, and Number of ...
5
votes
2answers
2k views

In what cases are BLOB and TEXT stored in-line on InnoDB?

I've googled this and can't find it, you can see Rick James mention it here. ... BLOB and TEXT are not always stored separately The answer on What is the difference between MySQL VARCHAR and TEXT ...
0
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1answer
60 views

Is file a basic form of database? [duplicate]

I’m having an interesting conversation with my friend who’s a developer. I’m a database admin. I say file is a basic form of database. I believe whatever that stores data can be called a database. He ...
2
votes
1answer
86 views

If a query reads more pages than the InnoDB buffer can hold, are all the previous pages evicted?

If I have some (hot) pages in the InnoDB buffer, and I perform a query which reads an amount of data larger than the buffer itself, will the hot pages be necessarily evicted?
4
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2answers
1k views

How does MySQL manage its memory with regards to indexes?

To start off, the reason I'm asking this, is because I feel I have a database that - according to my own estimates - should have been killing the disks with massive I/O, because of indexes not fitting ...
5
votes
1answer
880 views

Does partitioning help with lookups and inserts/updates by primary key?

I'm using MariaDB 10.1 and the default InnoDB storage storage, and I have a few tables with currently 10 to 100 million rows. These tables will keep growing a few million per month, and it's mostly ...
0
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1answer
55 views

LOAD DATA statement returns a syntax error a fraction of the time

MySQL 5.5.32, MyISAM A LOAD DATA INFILE statement usually executes and returns normally, succeeding at loading the data. On rare occasion it fails, returning a generic syntax error, always indicating ...
8
votes
2answers
660 views

Are columns which are not indexes, sorted on disk together with index?

Are columns which are not indexes, sorted on disk together with index, in MySQL, in MyISAM and InnoDB? An incorrect thought that I started to write: I think that probably not, since they are not ...
0
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3answers
392 views

Does database systems use basic system calls of local file system?

Suppose database system inserts a row in table, will it use write() system call of host file system to write that particular row to table?
2
votes
1answer
3k views

How does the alter command work internally when adding a column?

Can anyone explain what the internal operations are that takes place when an alter command is issued? How is column modified? Does it use created_tmp_tables or created_tmp_files? As per my test, I ...
14
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2answers
20k views

Why does MySQL allow HAVING to use SELECT aliases?

In SQL, as far as I know, the logical query processing order, which is the conceptual interpretation order, starts with FROM in the following way: FROM WHERE GROUP BY HAVING SELECT ORDER BY ...
1
vote
1answer
174 views

What is QP layer?

From blogs.innodb.com: InnoDB Memcached with Binlog Capability In our earlier Labs release, we presented a MySQL NoSQL solution through InnoDB Memcached Daemon Plugin (see earlier Calvin’s and my ...