InnoDB : MySQL's ACID-compliant Storage Engine

learn more… | top users | synonyms

1
vote
0answers
13 views

MySQL lost connection during query after specific record

I started getting the usual Error Code 2013 Lost connection to MYSQL server during query at a random moment when working on a PHP script. Some stuffs in the software still works, but the specific ...
0
votes
2answers
218 views

How can delete an orphaned temporary table on Mysql Innodb?

I was issuing an Alter table statement and suddenly the server crashed, Now i can not run any alter table to that table because it shows me the error 1050 and it says that a table named #sql1504d ...
2
votes
2answers
82 views

Will hacking away ibdata1 destroy databases with only MyISAM tables?

I made a mistake. I have a huge database of MyISAM tables that I was playing with converting [a copy of] to InnoDB. I didn't set innodb_file_per_table=1 before doing so. I know that safely shrinking ...
0
votes
2answers
132 views

Does MySQL Workbench lock database during migration process?

I am doing a migration of my database from one server (RDS) to another (localhost) via the MySQL workbench tool. I want to know if during this process my database will be locked for write and read ...
1
vote
2answers
48 views

Converting from InnoDB to InnoDB by file

I run MySQL and I have 7 schemas, 6 of the 7 schemas are MyISAM. In one of my schemas I have 20 tables that are InnoDB, the rest are MyISAM. I really want to convert those 20 tables over to InnoDB ...
1
vote
1answer
466 views

Mysql Tuning for a small server

I have a small Cloud Server running under Ubuntu 2 core, 2GB ram and 2GB swap, with Plesk Panel, Apache, Nginx as reverse proxy and Mysql 5.5. I have about 18 domains hosted here and each domain has ...
1
vote
2answers
33 views

guessing unused junk space in table. (innodb mysql/mariadb )

We have in every site (a dozen) one big database with lots of tables and record, using innodb as default and with innodb_file_per_table. from time to time we have space issue on some site and I am ...
1
vote
1answer
2k views

MySQL SELECT query hangs - Opening Tables INNODB

On my server I have 6 MySQL databases. They all power Wordpress websites. For some reason, 2 of these databases are not accessible. To my knowledge they use INNODB, but I can't confirm it as even ...
4
votes
1answer
481 views

Storing history of full/partial tables

I'm building a web-application with Django and MySQL (InnoDB) and am currently pondering over how to manage historical changes on various tables. I wonder if it's efficient to store a lot of rows ...
1
vote
1answer
159 views

Write-lock a whole table during transaction

I need to perform a delicate operation to my table in which I will solely insert, delete and select upon all of my rows and no God may interfere with the table during this operation: the table will be ...
0
votes
0answers
24 views

Can InnoDB use a clustered index as a covering index?

The scenario I have in mind is a query like: SELECT id FROM table WHERE id = ? or equivalently, SELECT 1 FROM table WHERE id = ? So here's some background: In a B+ tree (which InnoDB uses as ...
1
vote
1answer
332 views

MySQL: Merge Same Database on Several Location into Single Location

I have registration form, which exactly same for several location. Each of them has REG column, which this field is unique for each row. Basically each data input have different REG number for it, ...
6
votes
3answers
13k views

Mysql slowly uses memory until it starts to use swap

I am running a 1gb of RAM rackspace database server. For some reason in about 2 days the memory usage goes from using very little swap, to using 100mb. If I don't restart sql it will keep using more ...
3
votes
1answer
656 views

Select * from statement execute very slowly, innodb io read speed is low

I have a very simple query " select * from ap_statistic " running in my servers. the servers have the same hardware and software configuration (CPU 8 core, mem :32G, OS: redhat 5.5, mysql version: 5....
15
votes
3answers
6k views

Is the overhead of frequent query cache invalidation ever worth it?

I'm currently working on a MySQL database where we are seeing a large number of invalidations from the query cache, primarily because of the high number of INSERT, DELETE and UPDATE statements that ...
0
votes
0answers
22 views

InnoDB LSN in the future - how to insert the “required amount” of data?

Please forgive me - I'm not a DBA, I'm a lowly devops whose mysql DBA went on vacation the day before this happened and is gone for 10 days. I'm learning as much as I can about mysql/innodb/LSNs but I'...
0
votes
0answers
31 views

MySQL insert with sub select slow

We are using Python and LOAD DATA INFILE to load data from CSVs into our staging database. From staging we have sql scripts moving the data into our actual production database. LOAD DATA INFILE is ...
0
votes
0answers
24 views

Update on a table on MySQL Innodb seems to hang / lock forerever

When performing an update on a MySQL database for an InnoDB table, the update sentence never finishes. This is the update sentence from the MySQL query log: UPDATE `bb_plan` SET `creation_date` = '...
0
votes
1answer
32 views

How costly are InnoDB rollbacks?

I recently heard a fellow co-worker mention that InnoDB rollbacks are costly and negatively impact performance. How true is this statement? To give a context, we use spring+hibernate and set @...
1
vote
1answer
279 views

What's the approach to figure out reason for mysql crash?

The database I'm using crashes a lot recently. And I can't find a decent way to dig into the issue. I looked into mysql error log, but don't know how to start. I know there was a "load data infile" ...
1
vote
1answer
176 views

Why do innodb tables get corrupted so easily?

I'm upgrading a legacy system running MySQL 5.1 all the way to MariaDB 10. We're on a brand new Windows server, running XAMPP. I've done plenty of DB migrations in my time but this one has just been ...
2
votes
1answer
243 views

innodb , mysql Indexes difference when adding index

When I am altering one of my MySQL table to add an index I am getting below error in error log. Table a/b contains 4 indexes inside InnoDB, which is different from the number of indexes 3 defined ...
0
votes
0answers
23 views

Howto defrag a Galera Cluster (5.5.41) with innodb_file_per_table = off? After TRUNCATE a huge table is defrag needed?

First question how to defragment our cluster (see Galera and MariaDB config)? I don't know how Galera replicates the new data files size? Second question, is defrag needed? We truncated a 30 GB table ...
0
votes
1answer
155 views

Hash index for InnoDB

I saw a database schema that looked like this CREATE TABLE foo ( name_hash bigint, name varachar(500), a varchar(500), b varchar(500), ... PRIMARY KEY (name_hash), KEY ... ...
4
votes
2answers
6k views

show table name + number of records for each table in a mysql innodb database

How to list all tables in the current database, together the number of rows of the table. In other words, can you think of a query to come up with something like this in mysql? +---------------------...
66
votes
4answers
122k views

How large should be mysql innodb_buffer_pool_size?

I have a busy database with solely InnoDB tables which is about 5GB in size. The database runs on a Debian server using SSD disks and I've set max connections = 800 which sometimes saturate and grind ...
0
votes
1answer
44 views

MySQL MVCC implementation

The question is about the behavior of simultaneous SELECT and UPDATE in MySQL InnoDB table: We have a relatively large table which we periodically scan reading several fields including a field named, ...
0
votes
1answer
209 views

Too much IO to MySQL InnoDB log files

I am using MySQL version: 5.5.38 I have dedicated HDD to InnoDB log files using innodb-log-group-home-dir option. atopsar -d 30 shows big load (>50%) to this HDD The thing is that I have only 75 ...
5
votes
2answers
2k views

How much data is needed to show MySQL Cluster's performance scaling vs. InnoDB

I am evaluating MySQL Cluster as a possible replacement for an InnoDB schema. So far, I have tested it with 10s of MB of data, and found MySQL Cluster slower than InnoDB; however, I have been told ...
3
votes
1answer
64 views

MySQL applying second incremental backup causes LSN in the ibdata files to be higher than LSN in the ib_logfiles

Using the backup procedure described below, it gives warnings. These warnings start to appear from the 2nd till 6th (last) incremental backup that is being applied to the base backup. How to solve ...
2
votes
1answer
7k views

Configuring MySQL (my.cnf) for MyISAM and InnoDB

I want to convert some (not all) the MyISAM tables to InnoDB. Current my.cnf Show engines output Server has two 6-core Xeon processors (2 threads per core = 24 threads) What would be the best ...
0
votes
0answers
34 views

How to improve my big MySQL database with low concurrence?

I have a MySQL database who is been used to storage a large amount of data, it doesn't have a lot of concurrence( its minimum), but every day a big amounts of data is loaded and also a profiling ...
1
vote
1answer
1k views

Can't Delete Orphaned MySQL Temp Table

One of my servers had a hick-up yesterday and decided to leave temporary table while (while running alter table add indexes). ls -l sql -rw-rw---- 1 mysql mysql 8570 Mar 13 12:05 #sql-ib32694.frm -...
0
votes
2answers
1k views

Restore InnoDB to different machine

It was pointed to me from serverfault that the following question would be a better fit here so this is basically my original question from there. I currently have backups that were taken with ...
0
votes
0answers
18 views

InnoDB: Operating system error number 9

I got error when trying to backup with percona. Backup command [xtrabackup --backup --target-dir=/data/backups/mysql/] was worked and When I try to prepare backup [xtrabackup --prepare --target-dir=/...
0
votes
0answers
19 views

Innodb Change Buffer merge

I have been testing the performance of my innodb mysql. I ran a script which inserts and selects one after the other for 100000 times. So according to the change buffer concept, the inserted ...
0
votes
1answer
71 views

Memory(buffer pool) not populating on mysql start on Percona 5.6.28

We are testing Percona 5.6.28 at the moment, during our testing we found out even though the innodb_buffer_pool_populate is set to ON, it doesn't populate the memory(buffer pool) during mysql start. ...
5
votes
2answers
270 views

How to optimize indexes on MySQL query with various sorts

I have an INNODB table levels: +--------------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------------+--------...
1
vote
1answer
33 views

ALTER TABLE engine from MyISAM to InnoDB: why does mysqldump --order-by-primary help me?

I found an interesting mysqldump option in MySQL 5.7 Reference Manual. In internet there are no further details and explanations. --order-by-primary Dump each table's rows sorted by its primary ...
4
votes
2answers
372 views

Is it a waste to set innodb_buffer_pool_instances greater than the # of CPUs?

I set the innodb_buffer_pool_size to 20GB on a server with 12 CPU cores. My full database is 11gb, however most of it is archived tables that are almost never used. The total queried data is around 3 ...
1
vote
1answer
62 views

Converting a composite primary key to composite unique, and adding an auto-incremented PK column

Background I have taken over responsibility for a table that, in the long run, will grow monolithic. The table is a very simple link table with 2 columns, call them col1 and col2, both being foreign ...
1
vote
1answer
79 views

howto read/interpret “show engine innodb mutex” output?

We use a 3 node Galera cluster with version 5.5.41-MariaDB-wsrep MariaDB [(none)]> show engine innodb mutex; +--------+---------------------------------+------------------+ | Type | Name ...
0
votes
2answers
139 views

How does InnoDB access disk?

I know that block(multiple disk sectors) is the basic unit of data transfer for the virtual file system so, if NTFS uses 4 KB cluster size for files how does InnoDB access disk if it uses 8 KB page ...
0
votes
1answer
34 views

Mysql repetition of column in Criteria

What happens when I repeat the same column in the criteria part but with different values . For example col1 ='val1' or col1 = 'val2' or col1 = 'val3' . Assume col1 is not indexed. Will mysql ...
1
vote
1answer
49 views

How to fix `The table '/tmp/mysql/#sql_xxxxx' is full`?

Ubuntu server 16.04, php7, nginx 1.10, mysql 5.7 in Hyper-V on Windows 10 host How to fix The table '/tmp/mysql/#sql_xxxxx' is full ? In mysql-error.log [ERROR] InnoDB: Tablespace ...
0
votes
2answers
202 views

Best configuration for MySQL? InnoDB and MyISAM

I read that InnoDB is supposed to be better at writing into MySQL than MyISAM, however, I'm trying it out, by running 3000 MySQL queries(Inserting rows, 8 Columns + id)... but results haven't turned ...
0
votes
1answer
41 views

MySQL disk scanning algorithm [closed]

How does MySQL (InnoDB engine) read data from disk? What scanning algorithm does it use? Since the rows are stored in data pages will it read the entire data page to get the resulting rows?
0
votes
1answer
114 views

Missing statement information from 'LATEST DETECTED DEADLOCK' InnoDB status output

I'm learning how to interpret the LATEST DETECTED DEADLOCK section in the output of SHOW ENGINE INNODB STATUS, and had a question about the output. Some sample output of SHOW ENGINE INNODB STATUS ...
1
vote
1answer
300 views

Select only rows that equal x but not x and y?

I'm having quite the challenge with selecting hierarchical data in MySQL although I feel the schema should be optimized for it since it's based on the WordPress database model. I've got 4 tables: ...