InnoDB : MySQL's ACID-compliant Storage Engine

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4
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2answers
413 views

ib_logfile opened with O_SYNC when innodb_flush_method=O_DSYNC

mysql will open and flush data/log files as below when innodb_flush_method=O_DSYNC Open log Flush log Open datafile Flush data O_SYNC NONE NONE fsync () ...
0
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2answers
50 views

Memory leak on MySQL slave?

I have a Percona MySQL master-slave server configuration(5.6.20-68.0). The memory usage by MySQL on the slave server is constantly growing. Now it reached 68G despite on fact that ...
0
votes
1answer
121 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 ... ...
1
vote
1answer
120 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
59 views

ERROR 1031 (HY000) at line X: Table storage engine for 'TBL' doesn't have this option

I am trying to import mysqldump into following system: # cat /etc/redhat-release CentOS Linux release 7.2.1511 (Core) # rpm -qa | grep ^mysql mysql-community-libs-compat-5.7.11-1.el7.x86_64 ...
0
votes
1answer
916 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
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0answers
15 views

Boosting select queries during INSERT ON DUPLICATE KEY UPDATE into 150Gb innoDb table

I have a single server with 2 innoDb tables: 35Gb (partitioned, 24M rows), 150Gb (without partitioning, 220M rows). 25% data, 75% index. 99% of select queries are SUM + WHERE + GROUP BY. 100% of ...
4
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 ...
2
votes
1answer
80 views

Query about MySQL Semaphores in Engine Status

During a recent problem / slow down with one of our slave databases I noticed that when I ran SHOW ENGINE INNODB STATUS. I am getting the following: ---------- SEMAPHORES ---------- OS WAIT ARRAY ...
0
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0answers
29 views

Cannot open InnoDB table though the .frm file for the table exists

tonight, my local Server has crashed because the power went out. I do not have backups because this was only experimental. And for the sake of learning, I'd like to know what to do in this case. ...
0
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2answers
53 views

MySQL -Query with Union doesnt use index

Long story short, the following query runs immediately: SELECT COUNT(*) FROM indicators.fileso WHERE sha256 IN ( SELECT a.sha256 FROM temp.ananifilesinfo a JOIN indicators.filesi fi ON ...
1
vote
1answer
60 views

InnoDB MVCC vs Locking

From what I understand you InnoDB supports Row Level Locking MVCC (Multiversion Concurrency Control) Row Level Locking Locking is for when multiple writers are trying to update the same ...
1
vote
1answer
28 views

MySQL on idle low-end server unresponsive

I have a small virtual Server: 2 Cores, 2 GB RAM, Windows Server 2012 R2, Plesk, MySQL 5.6 (my.ini see below). Pagefile is disabled. Taskmanager says 1,3 GB RAM used. Only a single Wordpress ...
0
votes
1answer
108 views

Consistent backup of large DB --single-transaction

I need to mysqldump a large DB (330 GB) in order to set up a slave for replication. Does --single-transaction allow me to dump the entire DB without shutting mysql down and keeping it down for the ...
1
vote
2answers
29 views

MySQL Replication issues on server placed in different continents

I am running 2 cpanel servers with MySQL Replication set on them, one in france the other in US. Running a database hungary site. Replication was setup to load balance as well as for failover reason ...
4
votes
2answers
2k views

Are many NULL columns harmful in mysql InnoDB?

As I explored the clustered B-tree index system of InnoDB, I think that the presence of many NULL (or small) columns has no significant effect on InnoDB performance. Does the presence of excess ...
0
votes
1answer
19 views

Mysql locking - How to acquire a lock in the DB for each userId

Hi I have a J2EE Server(clustered) that executes requests from multiple users. I would like that each request of a given user will be handled like so: { acquireLockForUser(userId); // i.e. insert ...
3
votes
2answers
261 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
145 views

Benefits of using prepared statements in stored procedures?

Except from helping avoid SQL injection, what are the benefits - if any - of using prepared statements inside a store procedure (assume query is only executed once in the procedure)? Does the engine ...
1
vote
1answer
28 views

Cannot open some tables in phpmyadmin

Recently i get backup of my database from host in that backup i get table in .ibd,.frm,.myd format . I placed this files in xampp->mysql->data->test . Now i can open the tables in php ...
3
votes
1answer
635 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: ...
4
votes
2answers
342 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 ...
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0answers
46 views

How to convert .ibd files to .sql [closed]

Could any one please tell how to convert .ibd , .frm, .MYD, .MYI FILES TO .SQL . Or is there any way to open this files in php my admin .. Please tell how to convert this to .sql file
4
votes
2answers
76 views

What's the risk of keeping a table with row size > 8126 in MySQL 5.7?

I just upgraded from MySQL 5.6 to 5.7, and had the bad surprise to discover that a WordPress plugin table contains a ridiculous 438 fields, and exceeds the row size limit of 8126 bytes. Here is the ...
1
vote
1answer
1k views

Mysql Optimization suggessions

I have an InnoDB database table with more than 2 million rows. I am running efficienty indexed queries to reduce server load, but site becomes slower day by day. I ran Mysqltuner.pl to identify any ...
4
votes
1answer
11k views

MySQL: Row size too large (> 8126)

I have a table which has 300 columns in it. Each column is up to 255 bytes (there IS a business justification for this). When I try it create it using VARCHAR(255), I go past the limit for the ...
2
votes
2answers
8k views

Unable to drop the table since its showing waiting for meta data lock

We are trying to drop one table but it's getting hanged, and when we see the 'SHOW PROCESSLIST' command it's showing as 'waiting for meta data lock'. Even we are unable to perform any operation on ...
1
vote
1answer
116 views

autoincrement column issue in MYSQL

We are using an autoincrement column in a temporary table, and doing multiple time inserts. The autogenerated ids are not being generated consecutive (I have attached a sample simple query: 16 is ...
1
vote
1answer
29 views

Innodb Isolation levels and locking performance

I am reading a lot about locking and isolation levels in MySQL and InnoDB. I understood the technical differences and basic approach, but I still fail to understand a situation where for example READ ...
1
vote
2answers
50 views

Select query on an index column with gap locking

I am trying to understand in which cases will a select query make a gap locking on an indexed column select. What I read so far: Select queries use the repeatable read mode in InnoDB and will not ...
0
votes
2answers
71 views

Storing multiple types of users and their respective credentials in separate or same table?

So there have been many questions on Stack Exchange DBA and Stack Overflow that go close to answering this, but there's still some dispute within my team on how to properly do a database design. In ...
0
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1answer
100 views

Restore InnoDB from .frm files

My database crashed and my PC and I now only have the .frm and .ibd files left. Is there any way to restore my database?
3
votes
1answer
50 views

Dead Locks between an insert ignore and and an update

Using MySQL InnoDB. As far as I know and read so many time dead locks only happens when one transaction is locking resource A and waiting for B and another transaction does the opposite. So with ...
1
vote
1answer
39 views

My MySQL Server Died

Approximately 1 time per week my MySQL server is shutting down. This is what the log looks like: 2016-03-18 13:46:25 13166 [Warning] Buffered warning: Changed limits: max_open_files: 1024 ...
0
votes
0answers
12 views

innotop “Command Summary”

We provide DBaaS. This is innotop C output: We have only 8% read workload? The rest is write? I don't understand this is very uncommon workload for DBaaS? Statistics since last restart? What is ...
1
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0answers
231 views

Negative InnoDB Write Log efficiency in mysqltuner.pl results

I noticed something strange in results from mysqltuner.pl. I see this in mysqltuner output from three of my four servers with MariaDB 10.1.12: [OK] You have the latest version of ...
2
votes
0answers
54 views

InnoDB crashes on trx rollback

I have InnoDB assertion failure during the trx rollback 160316 10:47:31 InnoDB: Rolling back trx with id 5ADBE4173, 1 rows to undo 160316 10:47:31 InnoDB: Assertion failure in thread ...
2
votes
1answer
32 views

Saving data for a colossal maze

I want to build a labyrinth in which players can interact with others through leaving messages for one another, so in its most basic form each "tile" of the map is a forum thread or chat room. ...
0
votes
0answers
4 views

Different innodb_buffer_pool usage in nodes of a cluster

I have a 3-nodes Percona XtraDB Cluster (MySQL 5.6) that was put into operation three weeks ago. I noticed that the innodb_buffer_pool usage is very different in each of the nodes. In node #1, usage ...
0
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0answers
26 views

MySQL Storage Engine and Memory

I recently found out that, the databases does not have standard architecture(data model), some of them are, No relationship between tables(entities). No indexes defined. Only integer and varchar ...
1
vote
1answer
29 views

InnoDB slow query (few derived and dependent queries)

I have a select query which always worked pretty fast but data kept increasing which is why this query became very slow (2/3mins). I need to get all 0 values from those tables in the last WHERE ...
9
votes
4answers
18k views

How to get the most out of MySQL on a QuadCore machine with 16 GB of RAM?

I'm running a MySQL 5.5 server on my workstation for scientific data analysis and wonder how to configure MySQL in order to get the most out of it performance-wise. The types of query that I typically ...
0
votes
2answers
129 views

Multiple WHERE IN on multiple columns

I am not very experienced with sql queries and looking for an efficient way to perform the same WHERE IN condition on multiple columns. More specifically, i'm doing the following: SELECT a, b FROM ...
0
votes
2answers
6k views

Row size too large (> 8126)

I'm facing the following problem. Row size too large (> 8126). Changing some columns to TEXT or BLOB or using ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED may help. In current row format, ...
0
votes
1answer
18 views

InnoDB, Writing TRIGGER to INSERT into tables

Table1 "user_address" Field "u_id" Field "street_name" Field "locality_name" Table2 "street_master" Field "s_id" Field "s_name" I am supposed to write a trigger which BEFORE INSERT ON ...
3
votes
1answer
50 views

InnoDB - Intermittent CPU spikes on a large database

I have a machine with a large MySQL 5.6 database (multiple tables with 10-100 million rows). It has a considerable amount of load, especially during the evening and is running on a 16 core machine. ...
0
votes
1answer
56 views

Preventing MySQL index corruption

I'm having a recurring issue with a MySQL database where one index in particular has been getting corrupted. Originally I saw a corruption event about every 2-3 weeks and this week I've seen it happen ...
1
vote
3answers
50 views

character set, not set correctly

I have two database with a table with utf8 table, I wanted to change the encoding of a column, I used two scenarios but a problem happened to me. at first the table was like this : CREATE TABLE ...
1
vote
1answer
77 views

Can I emulate Oracle's autonomous transaction in MySQL?

I have a number of tables that have triggers on them that insert records in queueing and logging tables. The problem is that those inserts are then part of the same transaction. That means that any ...
0
votes
1answer
51 views

Mysql only using 10% of cache [duplicate]

I have a dedicated Mysql server that only uses 1.1 GB out of 16 GB ram (picture link 1). I belive this leads to my Disk I/O utilization beeing at 75% peaks (picture link1). How can i configure sql ...