i have a shell script that is called with a few parameters very frequently. it is supposed to build a query and execute the statement. in case an error occures, it should write the arguments seperated into a file so the error-handling can take place by calling that script again.
everything works but
the problem is, i catch connection refused error etc but if the statement cannot be executed because the table is locked and i do not want to wait for the timeout.
my code:
...
mysql -u ${username} -p${password} -h ${database} -P ${port} --connect-timeout=1 --skip-reconnect -e "$NQUERY"
mysqlstatus=$?
if [ $mysqlstatus -ne 0 ]; then
echo "[ERROR:QUERY COULD NOT BE EXECUTED:$mysqlstatus: QUERY WRITTEN TO LOG]" >> ${GENLOG}
#echo ${NQUERY} >> ${FQUER}
for i in "$#"; do
ARGS="$ARGS $i|"
done
echo "${ARGS}" >> ${ARGLOG}
else
echo "[OK] $NQUERY" >> ${GENLOG}
fi
...
but when a table is locked, the executing is not canceled and it runs like forever..
its not a solution for me to set the Max_statement_time_set or anything on the mysql server, since im not the only one using the db
You can use the timeout command along with mysql
timeout 3 mysql -u ...
This will wait 3 seconds for the mysql command to return, if the command runs longer then 3 seconds timeout will return exit status 124 to the shell. If you don't have timeout you can use job control with something like this.
#background the process
mysql -u ... &
#get pid of background process
bg_pid=$!
sleep 3
#check if your pid is still running
#using string matching incase pid was re assigned
if [[ $(ps -p $bg_pid -o args --no-headers) =~ "mysql" ]]
then
echo "running to long"
else
echo "OK"
fi
I'm trying to set variable in the cycle in Ubuntu bash, which is getting recordset from database, but this variable is setting to its previous value.
Here is a code:
#!/bin/bash
PREV_FILE_PATH="127"
while true
do
echo "$PREV_FILE_PATH"
mysql -h$DB_HOST -u $DB_USER -p$DB_PASS $DB_NAME --skip-column-names --default-character-set=UTF8 -e "here is a query" | while read "here is getting variables from recordset";
do
PREV_FILE_PATH="777"
done
done
And this code prints every time:
127
127
127
But whe I replaced this block-:
mysql -h$DB_HOST -u $DB_USER -p$DB_PASS $DB_NAME --skip-column-names --default-character-set=UTF8 -e "here is a query" | while read "here is getting variables from recordset";
with just while true and break at the end of cycle it works fine and prints:
127
777
777
777
Script creates some subshell and running that MySQL query in that subshell. So what should I do to make script change that variable?
As you noted the issue is due to the creation of a subshell which is being caused by piping the output of the mysql command to the while loop. A simple example:
PREV_FILE_PATH=127
echo test | while read _; do
PREV_FILE_PATH=777
done
echo $PREV_FILE_PATH
# output: 127
Since you're using BASH you can move the mysql command from being a pipe to a substituted process fed to the while loop via STDIN redirection. Using the previous simple example:
PREV_FILE_PATH=127
while read _; do
PREV_FILE_PATH=777
done < <(echo test)
echo $PREV_FILE_PATH
# output: 777
So to fix your code, you will want to move your mysql command in the same fashion that I moved the echo command above:
while read "here is getting variables from recordset"
do
PREV_FILE_PATH="777"
done < <(mysql -h$DB_HOST -u $DB_USER [..remaining options..])
Note that process substitution via <() is a BASH-ism and isn't POSIX compliant.
Performing automated database backups for starters and testing commands. I've found for performing an action on each line of a text file via BASH CLI is something to the effect of:
# while read line; do
COMMAND $line
done
I've created a list of the database names file:
# mysql -uroot -e "show databases" > databases
Then tried the following against the file to see if it would work correctly.
# while read line; do
"mysqldump -uroot $line > /dbbackups/$line.sql"
done
Seemingly, this would be working correctly but am met with the following error(s):
[04:58:46] [root#theia database-backup-testing]# cat databases | while read line ; do "mysqldump -uroot $line > $line.sql" ; done
-bash: mysqldump -uroot Database > Database.sql: command not found
-bash: mysqldump -uroot information_schema > information_schema.sql: command not found
-bash: mysqldump -uroot cphulkd > cphulkd.sql: command not found
I am not sure why it is giving command not found, when obviously, the output of the commands seems to be correct. I have also tried using the absolute path of mysqldump (/usr/bin/mysqldump) but it gives the same error(s).
Can anyone fill me in on why this is happening?
EDIT: I found a fix:
The script works if the quotes are removed:
# cat databases |
while read line; do
mysqldump -uroot $line > $line.sql
done
Apparently, the quotes causes it to execute as a string and not a command.
why it is giving command not found
Your quotes are not correct, Try something like this:
while read line ; do mysqldump -uroot "$line" > "$line".sql ; done
Haven't used mysqldump so I cant help with the syntax of the specific command.
Here's a bash script that solves this:
https://github.com/jeevandongre/backup-restore
I'm doing a bash script that interacts with a MySQL datatabase using the mysql command line programme. I want to use table locks in my SQL. Can I do this?
mysql -e "LOCK TABLES mytable"
# do some bash stuff
mysql -u "UNLOCK TABLES"
The reason I ask, is because table locks are only kept for the session, so wouldn't the lock be released as soon as that mysql programme finishes?
[EDIT]
nos had the basic idea -- only run "mysql" once, and the solution nos provided should work, but it left the FIFO on disk.
nos was also correct that I screwed up: a simple "echo X >FIFO" will close the FIFO; I remembered wrongly. And my (removed) comments w.r.t. timing don't apply, sorry.
That said, you don't need a FIFO, you could use an inter-process pipe. And looking through my old MySQL scripts, some worked akin to this, but you cannot let any commands write to stdout (without some "exec" tricks).
#!/bin/bash
(
echo "LOCK TABLES mytable READ ;"
echo "Doing something..." >&2
echo "describe mytable;"
sleep 5
echo "UNLOCK tables;"
) | mysql ${ARGUMENTS}
Another option might be to assign a file descriptor to the FIFO, then have it run in the background. This is very similar to what nos did, but the "exec" option wouldn't require a subshell to run the bash commands; hence would allow you to set "RC" in the "other stuff":
#!/bin/bash
# Use the PID ($$) in the FIFO and remove it on exit:
FIFO="/tmp/mysql-pipe.$$"
mkfifo ${FIFO} || exit $?
RC=0
# Tie FD3 to the FIFO (only for writing), then start MySQL in the u
# background with its input from the FIFO:
exec 3<>${FIFO}
mysql ${ARGUMENTS} <${FIFO} &
MYSQL=$!
trap "rm -f ${FIFO};kill -1 ${MYSQL} 2>&-" 0
# Now lock the table...
echo "LOCK TABLES mytable WRITE;" >&3
# ... do your other stuff here, set RC ...
echo "DESCRIBE mytable;" >&3
sleep 5
RC=3
# ...
echo "UNLOCK TABLES;" >&3
exec 3>&-
# You probably wish to sleep for a bit, or wait on ${MYSQL} before you exit
exit ${RC}
Note that there are a few control issues:
This code has NO ERROR CHECKING for failure to lock (or any SQL commands
within the "other stuff"). And that's definitely non-trivial.
Since in the first example, the "other stuff" is within a subshell, you cannot easily
set the return code of the script from that context.
Here's one way, I'm sure there's an easier way though..
mkfifo /tmp/mysql-pipe
mysql mydb </tmp/mysql-pipe &
(
echo "LOCK TABLES mytable READ ;" 1>&6
echo "Doing something "
echo "UNLOCK tables;" 1>&6
) 6> /tmp/mysql-pipe
A very interesting approach I found out while looking into this issue for my own, is by using MySQL's SYSTEM command. I'm not still sure what exactly are the drawbacks, if any, but it will certainly work for a lot of cases:
Example:
mysql <<END_HEREDOC
LOCK TABLES mytable;
SYSTEM /path/to/script.sh
UNLOCK TABLES;
END_HEREDOC
It's worth noting that this only works on *nix, obviously, as does the SYSTEM command.
Credit goes to Daniel Kadosh: http://dev.mysql.com/doc/refman/5.5/en/lock-tables.html#c10447
Another approach without the mkfifo commands:
cat <(echo "LOCK TABLES mytable;") <(sleep 3600) | mysql &
LOCK_PID=$!
# BASH STUFF
kill $LOCK_PID
I think Amr's answer is the simplest. However I wanted to share this because someone else may also need a slightly different answer.
The sleep 3600 pauses the input for 1 hour. You can find other commands to make it pause here: https://unix.stackexchange.com/questions/42901/how-to-do-nothing-forever-in-an-elegant-way
The lock tables SQL runs immediately, then it will wait for the sleep timer.
Problem and limitation in existing answers
Answers by NVRAM, nos and xer0x
If commands between LOCK TABLES and UNLOCK TABLES are all SQL queries, you should be fine.
In this case, however, why don't we just simply construct a single SQL file and pipe it to the mysql command?
If there are commands other than issuing SQL queries in the critical section, you could be running into trouble.
The echo command that sends the lock statement to the file descriptor doesn't block and wait for mysql to respond.
Subsequent commands are therefore possible to be executed before the lock is actually acquired. Synchronization aren't guaranteed.
Answer by Amr Mostafa
The SYSTEM command is executed on the MySQL server. So the script or command to be executed must be present on the same MySQL server.
You will need terminal access to the machine/VM/container that host the server (or at least a mean to transfer your script to the server host).
SYSTEM command also works on Windows as of MySQL 8.0.19, but running it on a Windows server of course means you will be running a Windows command (e.g. batch file or PowerShell script).
A modified solution
Below is a example solution based on the answers by NVRAM and nos, but waits for lock:
#!/bin/bash
# creates named pipes for attaching to stdin and stdout of mysql
mkfifo /tmp/mysql.stdin.pipe /tmp/mysql.stdout.pipe
# unbuffered option to ensure mysql doesn't buffer the output, so we can read immediately
# batch and skip-column-names options are for ease of parsing the output
mysql --unbuffered --batch --skip-column-names $OTHER_MYSQL_OPTIONS < /tmp/mysql.stdin.pipe > /tmp/mysql.stdout.pipe &
PID_MYSQL=$!
# make sure to stop mysql and remove the pipes before leaving
cleanup_proc_pipe() {
kill $PID_MYSQL
rm -rf /tmp/mysql.stdin.pipe /tmp/mysql.stdout.pipe
}
trap cleanup_proc_pipe EXIT
# open file descriptors for writing and reading
exec 10>/tmp/mysql.stdin.pipe
exec 11</tmp/mysql.stdout.pipe
# update the cleanup procedure to close the file descriptors
cleanup_fd() {
exec 10>&-
exec 11>&-
cleanup_proc_pipe
}
trap cleanup_fd EXIT
# try to obtain lock with 5 seconds of timeout
echo 'SELECT GET_LOCK("my_lock", 5);' >&10
# read stdout of mysql with 6 seconds of timeout
if ! read -t 6 line <&11; then
echo "Timeout reading from mysql"
elif [[ $line == 1 ]]; then
echo "Lock acquired successfully"
echo "Doing some critical stuff..."
echo 'DO RELEASE_LOCK("my_lock");' >&10
else
echo "Timeout waiting for lock"
fi
The above example uses SELECT GET_LOCK() to enter the critical section. It produces output for us to parse the result and decide what to do next.
If you need to execute statements that doesn't produce output (e.g. LOCK TABLES and START TRANSACTION), you may perform a dummy SELECT 1; after such statement and read from the stdout with a reasonable timeout. E.g.:
# ...
echo 'LOCK TABLES my_table WRITE;' >&10
echo 'SELECT 1;' >&10
if ! read -t 10 line <&11; then
echo "Timeout reading from mysql"
elif [[ $line == 1 ]]; then
echo "Table lock acquired"
# ...
else
echo "Unexpected output?!"
fi
You may also want to attach a third named pipe to stderr of mysql to handle different cases of error.
I would like to write a script which copies my current database sitedb1 to sitedb2 on the same mysql database instance. I know I can dump the sitedb1 to a sql script:
mysqldump -u root -p sitedb1 >~/db_name.sql
and then import it to sitedb2.
Is there an easier way, without dumping the first database to a sql file?
As the manual says in Copying Databases you can pipe the dump directly into the mysql client:
mysqldump db_name | mysql new_db_name
If you're using MyISAM you could copy the files, but I wouldn't recommend it. It's a bit dodgy.
Integrated from various good other answers
Both mysqldump and mysql commands accept options for setting connection details (and much more), like:
mysqldump -u <user name> --password=<pwd> <original db> | mysql -u <user name> -p <new db>
Also, if the new database is not existing yet, you have to create it beforehand (e.g. with echo "create database new_db_name" | mysql -u <dbuser> -p).
Using MySQL Utilities
The MySQL Utilities contain the nice tool mysqldbcopy which by default copies a DB including all related objects (“tables, views, triggers, events, procedures, functions, and database-level grants”) and data from one DB server to the same or to another DB server. There are lots of options available to customize what is actually copied.
So, to answer the OP’s question:
mysqldbcopy \
--source=root:your_password#localhost \
--destination=root:your_password#localhost \
sitedb1:sitedb2
Best and easy way is to enter these commands in your terminal and set permissions to the root user. Works for me..!
:~$> mysqldump -u root -p db1 > dump.sql
:~$> mysqladmin -u root -p create db2
:~$> mysql -u root -p db2 < dump.sql
mysqladmin create DB_name -u DB_user --password=DB_pass && \
mysqldump -u DB_user --password=DB_pass DB_name | \
mysql -u DB_user --password=DB_pass -h DB_host DB_name
You could use (in pseudocode):
FOREACH tbl IN db_a:
CREATE TABLE db_b.tbl LIKE db_a.tbl;
INSERT INTO db_b.tbl SELECT * FROM db_a.tbl;
The reason I'm not using the CREATE TABLE ... SELECT ... syntax is to preserve indices. Of course this only copies tables. Views and procedures are not copied, although it can be done in the same manner.
See CREATE TABLE.
You need to run the command from terminal / command prompt.
mysqldump -u <user name> -p <pwd> <original db> | mysql -u <user name> <pwd> <new db>
e.g: mysqldump -u root test_db1 | mysql -u root test_db2
This copies test_db1 to test_db2 and grant the access to 'root'#'localhost'
First create the duplicate database:
CREATE DATABASE duplicateddb;
Make sure the permissions etc are all in place and:
mysqldump -u admin -p originaldb | mysql -u backup -p password duplicateddb;
A simple way to do so if you installed phpmyadmin:
Go to your database, select "operation" tab, and you can see the "copy database to" block. Use it and you can copy the database.
As mentioned in Greg's answer, mysqldump db_name | mysql new_db_name is the free, safe, and easy way to transfer data between databases. However, it's also really slow.
If you're looking to backup data, can't afford to lose data (in this or other databases), or are using tables other than innodb, then you should use mysqldump.
If you're looking for something for development, have all of your databases backed up elsewhere, and are comfortable purging and reinstalling mysql (possibly manually) when everything goes wrong, then I might just have the solution for you.
I couldn't find a good alternative, so I built a script to do it myself. I spent a lot of time getting this to work the first time and it honestly terrifies me a little to make changes to it now. Innodb databases were not meant to copied and pasted like this. Small changes cause this to fail in magnificent ways. I haven't had a problem since I finalized the code, but that doesn't mean you won't.
Systems tested on (but may still fail on):
Ubuntu 16.04, default mysql, innodb, separate files per table
Ubuntu 18.04, default mysql, innodb, separate files per table
We've since switched to docker and a simple copy of the entire mysql data folder, so this script is no longer maintained. Leaving it in case it's able to help anyone in the future.
What it does
Gets sudo privilege and verifies you have enough storage space to clone the database
Gets root mysql privileges
Creates a new database named after the current git branch
Clones structure to new database
Switches into recovery mode for innodb
Deletes default data in new database
Stops mysql
Clones data to new database
Starts mysql
Links imported data in new database
Switches out of recovery mode for innodb
Restarts mysql
Gives mysql user access to database
Cleans up temporary files
How it compares with mysqldump
On a 3gb database, using mysqldump and mysql would take 40-50 minutes on my machine. Using this method, the same process would only take ~8 minutes.
How we used it
We had our SQL changes saved alongside our code and the upgrade process is automated on both production and development, with each set of changes making a backup of the database to restore if there's errors. One problem we ran into was when we were working on a long term project with database changes, and had to switch branches in the middle of it to fix a bug or three.
In the past, we used a single database for all branches, and would have to rebuild the database whenever we switched to a branch that wasn't compatible with the new database changes. And when we switched back, we'd have to run the upgrades again.
We tried mysqldump to duplicate the database for different branches, but the wait time was too long (40-50 minutes), and we couldn't do anything else in the meantime.
This solution shortened the database clone time to 1/5 the time (think coffee and bathroom break instead of a long lunch).
Common tasks and their time
Switching between branches with incompatible database changes takes 50+ minutes on a single database, but no time at all after the initial setup time with mysqldump or this code. This code just happens to be ~5 times faster than mysqldump.
Here are some common tasks and roughly how long they would take with each method:
Create feature branch with database changes and merge immediately:
Single database: ~5 minutes
Clone with mysqldump: 50-60 minutes
Clone with this code: ~18 minutes
Create feature branch with database changes, switch to main for a bugfix, make an edit on the feature branch, and merge:
Single database: ~60 minutes
Clone with mysqldump: 50-60 minutes
Clone with this code: ~18 minutes
Create feature branch with database changes, switch to main for a bugfix 5 times while making edits on the feature branch inbetween, and merge:
Single database: ~4 hours, 40 minutes
Clone with mysqldump: 50-60 minutes
Clone with this code: ~18 minutes
The code
Do not use this unless you've read and understood everything above. It is no longer maintained, so it is more and more likely to be broken as time goes on.
#!/bin/bash
set -e
# This script taken from: https://stackoverflow.com/a/57528198/526741
function now {
date "+%H:%M:%S";
}
# Leading space sets messages off from step progress.
echosuccess () {
printf "\e[0;32m %s: %s\e[0m\n" "$(now)" "$1"
sleep .1
}
echowarn () {
printf "\e[0;33m %s: %s\e[0m\n" "$(now)" "$1"
sleep .1
}
echoerror () {
printf "\e[0;31m %s: %s\e[0m\n" "$(now)" "$1"
sleep .1
}
echonotice () {
printf "\e[0;94m %s: %s\e[0m\n" "$(now)" "$1"
sleep .1
}
echoinstructions () {
printf "\e[0;104m %s: %s\e[0m\n" "$(now)" "$1"
sleep .1
}
echostep () {
printf "\e[0;90mStep %s of 13:\e[0m\n" "$1"
sleep .1
}
MYSQL_CNF_PATH='/etc/mysql/mysql.conf.d/recovery.cnf'
OLD_DB='YOUR_DATABASE_NAME'
USER='YOUR_MYSQL_USER'
# You can change NEW_DB to whatever you like
# Right now, it will append the current git branch name to the existing database name
BRANCH=`git rev-parse --abbrev-ref HEAD`
NEW_DB="${OLD_DB}__$BRANCH"
THIS_DIR=./site/upgrades
DB_CREATED=false
tmp_file () {
printf "$THIS_DIR/$NEW_DB.%s" "$1"
}
sql_on_new_db () {
mysql $NEW_DB --unbuffered --skip-column-names -u root -p$PASS 2>> $(tmp_file 'errors.log')
}
general_cleanup () {
echoinstructions 'Leave this running while things are cleaned up...'
if [ -f $(tmp_file 'errors.log') ]; then
echowarn 'Additional warnings and errors:'
cat $(tmp_file 'errors.log')
fi
for f in $THIS_DIR/$NEW_DB.*; do
echonotice 'Deleting temporary files created for transfer...'
rm -f $THIS_DIR/$NEW_DB.*
break
done
echonotice 'Done!'
echoinstructions "You can close this now :)"
}
error_cleanup () {
exitcode=$?
# Just in case script was exited while in a prompt
echo
if [ "$exitcode" == "0" ]; then
echoerror "Script exited prematurely, but exit code was '0'."
fi
echoerror "The following command on line ${BASH_LINENO[0]} exited with code $exitcode:"
echo " $BASH_COMMAND"
if [ "$DB_CREATED" = true ]; then
echo
echonotice "Dropping database \`$NEW_DB\` if created..."
echo "DROP DATABASE \`$NEW_DB\`;" | sql_on_new_db || echoerror "Could not drop database \`$NEW_DB\` (see warnings)"
fi
general_cleanup
exit $exitcode
}
trap error_cleanup EXIT
mysql_path () {
printf "/var/lib/mysql/"
}
old_db_path () {
printf "%s%s/" "$(mysql_path)" "$OLD_DB"
}
new_db_path () {
printf "%s%s/" "$(mysql_path)" "$NEW_DB"
}
get_tables () {
(sudo find /var/lib/mysql/$OLD_DB -name "*.frm" -printf "%f\n") | cut -d'.' -f1 | sort
}
STEP=0
authenticate () {
printf "\e[0;104m"
sudo ls &> /dev/null
printf "\e[0m"
echonotice 'Authenticated.'
}
echostep $((++STEP))
authenticate
TABLE_COUNT=`get_tables | wc -l`
SPACE_AVAIL=`df -k --output=avail $(mysql_path) | tail -n1`
SPACE_NEEDED=(`sudo du -s $(old_db_path)`)
SPACE_ERR=`echo "$SPACE_AVAIL-$SPACE_NEEDED" | bc`
SPACE_WARN=`echo "$SPACE_AVAIL-$SPACE_NEEDED*3" | bc`
if [ $SPACE_ERR -lt 0 ]; then
echoerror 'There is not enough space to branch the database.'
echoerror 'Please free up some space and run this command again.'
SPACE_AVAIL_FORMATTED=`printf "%'d" $SPACE_AVAIL`
SPACE_NEEDED_FORMATTED=`printf "%'${#SPACE_AVAIL_FORMATTED}d" $SPACE_NEEDED`
echonotice "$SPACE_NEEDED_FORMATTED bytes needed to create database branch"
echonotice "$SPACE_AVAIL_FORMATTED bytes currently free"
exit 1
elif [ $SPACE_WARN -lt 0 ]; then
echowarn 'This action will use more than 1/3 of your available space.'
SPACE_AVAIL_FORMATTED=`printf "%'d" $SPACE_AVAIL`
SPACE_NEEDED_FORMATTED=`printf "%'${#SPACE_AVAIL_FORMATTED}d" $SPACE_NEEDED`
echonotice "$SPACE_NEEDED_FORMATTED bytes needed to create database branch"
echonotice "$SPACE_AVAIL_FORMATTED bytes currently free"
printf "\e[0;104m"
read -p " $(now): Do you still want to branch the database? [y/n] " -n 1 -r CONFIRM
printf "\e[0m"
echo
if [[ ! $CONFIRM =~ ^[Yy]$ ]]; then
echonotice 'Database was NOT branched'
exit 1
fi
fi
PASS='badpass'
connect_to_db () {
printf "\e[0;104m %s: MySQL root password: \e[0m" "$(now)"
read -s PASS
PASS=${PASS:-badpass}
echo
echonotice "Connecting to MySQL..."
}
create_db () {
echonotice 'Creating empty database...'
echo "CREATE DATABASE \`$NEW_DB\` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci" | mysql -u root -p$PASS 2>> $(tmp_file 'errors.log')
DB_CREATED=true
}
build_tables () {
echonotice 'Retrieving and building database structure...'
mysqldump $OLD_DB --skip-comments -d -u root -p$PASS 2>> $(tmp_file 'errors.log') | pv --width 80 --name " $(now)" > $(tmp_file 'dump.sql')
pv --width 80 --name " $(now)" $(tmp_file 'dump.sql') | sql_on_new_db
}
set_debug_1 () {
echonotice 'Switching into recovery mode for innodb...'
printf '[mysqld]\ninnodb_file_per_table = 1\ninnodb_force_recovery = 1\n' | sudo tee $MYSQL_CNF_PATH > /dev/null
}
set_debug_0 () {
echonotice 'Switching out of recovery mode for innodb...'
sudo rm -f $MYSQL_CNF_PATH
}
discard_tablespace () {
echonotice 'Unlinking default data...'
(
echo "USE \`$NEW_DB\`;"
echo "SET foreign_key_checks = 0;"
get_tables | while read -r line;
do echo "ALTER TABLE \`$line\` DISCARD TABLESPACE; SELECT 'Table \`$line\` imported.';";
done
echo "SET foreign_key_checks = 1;"
) > $(tmp_file 'discard_tablespace.sql')
cat $(tmp_file 'discard_tablespace.sql') | sql_on_new_db | pv --width 80 --line-mode --size $TABLE_COUNT --name " $(now)" > /dev/null
}
import_tablespace () {
echonotice 'Linking imported data...'
(
echo "USE \`$NEW_DB\`;"
echo "SET foreign_key_checks = 0;"
get_tables | while read -r line;
do echo "ALTER TABLE \`$line\` IMPORT TABLESPACE; SELECT 'Table \`$line\` imported.';";
done
echo "SET foreign_key_checks = 1;"
) > $(tmp_file 'import_tablespace.sql')
cat $(tmp_file 'import_tablespace.sql') | sql_on_new_db | pv --width 80 --line-mode --size $TABLE_COUNT --name " $(now)" > /dev/null
}
stop_mysql () {
echonotice 'Stopping MySQL...'
sudo /etc/init.d/mysql stop >> $(tmp_file 'log')
}
start_mysql () {
echonotice 'Starting MySQL...'
sudo /etc/init.d/mysql start >> $(tmp_file 'log')
}
restart_mysql () {
echonotice 'Restarting MySQL...'
sudo /etc/init.d/mysql restart >> $(tmp_file 'log')
}
copy_data () {
echonotice 'Copying data...'
sudo rm -f $(new_db_path)*.ibd
sudo rsync -ah --info=progress2 $(old_db_path) --include '*.ibd' --exclude '*' $(new_db_path)
}
give_access () {
echonotice "Giving MySQL user \`$USER\` access to database \`$NEW_DB\`"
echo "GRANT ALL PRIVILEGES ON \`$NEW_DB\`.* to $USER#localhost" | sql_on_new_db
}
echostep $((++STEP))
connect_to_db
EXISTING_TABLE=`echo "SELECT SCHEMA_NAME FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = '$NEW_DB'" | mysql --skip-column-names -u root -p$PASS 2>> $(tmp_file 'errors.log')`
if [ "$EXISTING_TABLE" == "$NEW_DB" ]
then
echoerror "Database \`$NEW_DB\` already exists"
exit 1
fi
echoinstructions "The hamsters are working. Check back in 5-10 minutes."
sleep 5
echostep $((++STEP))
create_db
echostep $((++STEP))
build_tables
echostep $((++STEP))
set_debug_1
echostep $((++STEP))
discard_tablespace
echostep $((++STEP))
stop_mysql
echostep $((++STEP))
copy_data
echostep $((++STEP))
start_mysql
echostep $((++STEP))
import_tablespace
echostep $((++STEP))
set_debug_0
echostep $((++STEP))
restart_mysql
echostep $((++STEP))
give_access
echo
echosuccess "Database \`$NEW_DB\` is ready to use."
echo
trap general_cleanup EXIT
If everything goes smoothly, you should see something like:
You can do something like the following:
mysqldump -u[username] -p[password] database_name_for_clone
| mysql -u[username] -p[password] new_database_name
You can do:
CREATE DATABASE copy_of_db;
create table copy_of_db.table LIKE source_db.table;
If you want to copy data too:
INSERT INTO copy_of_db.table SELECT * FROM source_db.table;
Repeat for all tables, functions, procedures, etc
(mysqldump is the proper way, but this is a quick and dirty solution useful in many cases)
This statement was added in MySQL 5.1.7 but was found to be dangerous and was removed in MySQL 5.1.23. It was intended to enable upgrading pre-5.1 databases to use the encoding implemented in 5.1 for mapping database names to database directory names. However, use of this statement could result in loss of database contents, which is why it was removed. Do not use RENAME DATABASE in earlier versions in which it is present.
To perform the task of upgrading database names with the new encoding, use ALTER DATABASE db_name UPGRADE DATA DIRECTORY NAME instead: http://dev.mysql.com/doc/refman/5.1/en/alter-database.html
Using Mydumper
sudo apt install mydumper
Generate dump
mydumper --user=YOUR_USER --password=YOUR_PASSWORD -B YOUR_CURRENT_DB \
--triggers --routines --events --outputdir YOUR_OUTPUT_DIR
Load dump
myloader --user=YOUR_USER --password=YOUR_PASSWORD --database=YOUR_NEW_DB \
--directory=YOUR_OUTPUT_DIR
In addition to Greg's answer, this is the easiest and fastest way if the new_db_name doesn't yet exist:
echo "create database new_db_name" | mysql -u <user> -p <pwd>
mysqldump -u <user> -p <pwd> db_name | mysql -u <user> -p <pwd> new_db_name
If you have triggers in your original database, you can avoid the "Trigger already exists" error by piping a replacement before the import:
mysqldump -u olddbuser -p -d olddbname | sed "s/`olddbname`./`newdbname`./" | mysql -u newdbuser -p -D newdbname
Using MySQL Workbench you can use Database > Migration Wizard to copy database to the same or to the other server instance. I believe it works server-side so it should be a good solution for duplicating large databases.