Backing Up Views with Mysql Dump

I want to 开发者_JAVA百科back up only the Views with mysqldump.

Is this possible?

If so, how?

NOTE: This answer from Ken moved from suggested edit to own answer.

here's a full command line example using a variant of the above

 mysql -u username INFORMATION_SCHEMA
  --skip-column-names --batch
  -e "select table_name from tables where table_type = 'VIEW'
      and table_schema = 'database'"
  | xargs mysqldump -u username database
  > views.sql

This extracts all of the view names via a query to the INFORMATION_SCHEMA database, then pipes them to xargs to formulate a mysqldump command. --skip-column-names and --batch are needed to make the output xargs friendly. This command line might get too long if you have a lot of views, in which case you'd want to add some sort of additional filter to the select (e.g. look for all views starting with a given character).

Backing up views over multiple databases can be done by just using information_schema:

mysql --skip-column-names --batch -e 'select CONCAT("DROP TABLE IF EXISTS ", TABLE_SCHEMA, ".", TABLE_NAME, "; CREATE OR REPLACE VIEW ", TABLE_SCHEMA, ".", TABLE_NAME, " AS ", VIEW_DEFINITION, "; ") table_name from information_schema.views'

I modified Andomar's excellent answer to allow the database (and other settings) to only be specified once:

#!/bin/bash -e
mysql --skip-column-names --batch -e \
"select table_name from information_schema.views \
 where table_schema = database()" $* |
xargs --max-args 1 mysqldump $*

I save this as mysql-dump-views.sh and call it via:

$ mysql-dump-views.sh -u user -ppassword databasename >dumpfile.sql

By backup, I'm assuming you mean just the definition without the data.

It seems that right now mysqldump doesn't distinguish between VIEWs and TABLEs, so perhaps the best thing to do is to either specify the VIEWs explicitly on the command line to mysqldump or figure out this list dynamically before mysqldump and then passing it down like before.

You can get all the VIEWs in a specific database using this query:

SHOW FULL TABLES WHERE table_type='view';

In terms of answering this question, olliiiver's answer is the best for doing this directly. For my answer I will try to build that into a comprehensive full backup and restore solution.

With the help of the other answers in this question, and a few other resources, I came up with this script for easily replacing the database on my development server with a live copy from the production server on demand. It works on one database at a time, rather than all databases. While I do have a separate script for that, it is not safe to share here as it basically drops and recreates everything except for a select few databases, and your environment may vary.

The script assumes root system and MySQL user on both machines (though that can be changed), working passwordless SSH between servers, and relies on a MySQL password file /root/mysqlroot.cnf on each machine, which looks like this:

[client]
password=YourPasswordHere

File: synctestdb.sh, optionally symlinked to /usr/sbin/synctestdb for ease of use

Usage: synctestdb DBNAME DESTSERVER

Run it from the production server.

Here it is:

#!/bin/bash

if [ "${1}" != "" ] && [ "${1}" != "--help" ] && [ "${2}" != "" ] ; then

    DBNAME=${1}
    DESTSERVER=${2}
    BKDATE=$( date "+%Y-%m-%d" );
    SRCHOSTNAME=$( /bin/hostname )
    EXPORTPATH=/tmp
    EXPORTFILE=/tmp/${SRCHOSTNAME}_sql_${BKDATE}_devsync.sql
    CREDSFILE=/root/mysqlroot.cnf
    SSHUSER=root

    DBEXISTS=$( echo "SHOW DATABASES LIKE '${DBNAME}'" \
      | mysql --defaults-extra-file=${CREDSFILE} -NB INFORMATION_SCHEMA )

    if [ "${DBEXISTS}" == "${DBNAME}" ] ; then
        echo Preparing --ignore-tables parameters for all relevant views
        echo
        #build --ignore-table parameters list from list of all views in
        #relevant database - as mysqldump likes to recreate views as tables
        #we pair this with an export of the view definitions later below
        SKIPVIEWS=$(mysql --defaults-extra-file=${CREDSFILE} \
          -NB \
          -e "SELECT \
            CONCAT( '--ignore-table=', TABLE_SCHEMA, '.', TABLE_NAME ) AS q \
            FROM INFORMATION_SCHEMA.VIEWS \
            WHERE TABLE_SCHEMA = '${DBNAME}';" )

        if [ "$?" == "0" ] ; then

            echo Exporting database ${DBNAME}
            echo
            mysqldump --defaults-extra-file=${CREDSFILE} ${SKIPVIEWS}  \
              --add-locks --extended-insert --flush-privileges --no-autocommit \
              --routines --triggers --single-transaction --master-data=2 \
              --flush-logs --events --quick --databases ${DBNAME} > ${EXPORTFILE} \
              || echo -e "\n\nERROR: ${SRCHOSTNAME} failed to mysqldump ${DBNAME}"
            echo Exporting view definitions
            echo
            mysql --defaults-extra-file=${CREDSFILE} \
              --skip-column-names --batch \
              -e "SELECT \
                CONCAT( \
                'DROP TABLE IF EXISTS ', TABLE_SCHEMA, '.', TABLE_NAME, \
                '; CREATE OR REPLACE VIEW ', TABLE_SCHEMA, '.', TABLE_NAME, ' AS ', \
                VIEW_DEFINITION, '; ') AS TABLE_NAME FROM INFORMATION_SCHEMA.VIEWS \
                WHERE TABLE_SCHEMA = '${DBNAME}';" >> ${EXPORTFILE} \
              || echo -e "\n\nERROR: ${SRCHOSTNAME} failed to mysqldump view definitions"
            echo Export complete, preparing to transfer export file and import
            echo
            STATUSMSG="SUCCESS: database ${DBNAME} synced from ${SRCHOSTNAME} to ${DESTSERVER}"
            scp \
              ${EXPORTFILE} \
              ${SSHUSER}@${DESTSERVER}:${EXPORTPATH}/ \
              || STATUSMSG="ERROR: Failed to SCP file to remote server ${DESTSERVER}"
            ssh ${SSHUSER}@${DESTSERVER} \
              "mysql --defaults-extra-file=${CREDSFILE} < ${EXPORTFILE}" \
              || STATUSMSG="ERROR: Failed to update remote server ${DESTSERVER}"
            ssh ${SSHUSER}@${DESTSERVER} \
              "rm ${EXPORTFILE}" \
              || STATUSMSG="ERROR: Failed to remove import file from remote server ${DESTSERVER}"
            rm ${EXPORTFILE}
            echo ${STATUSMSG}

        else
            echo "ERROR: could not obtain list of views from INFORMATION_SCHEMA"
        fi

    else
        echo "ERROR: specified database not found, or SQL credentials file not found"
    fi

else
    echo -e "Usage: synctestdb DBNAME DESTSERVER \nPlease only run this script from the live production server\n"
fi

So far it appears to work, though you may want to tweak it for your purposes. Be sure that wherever your credentials file is, it is set with secure access rights, so that unauthorized users cannot read it!

As it seems to be difficult to export views properly, I adapted olliiiver's answer to make it so that first we delete any tables or views with the exact names of valid views on the database we are importing into in case they exist, then importing all tables, which may erroneously create those views as tables, then delete those tables and define those views properly.

Basically here is how it works:

• verify existence of the database you specified on the command line
• use MYSQLDUMP to create a dump file
• SCP the dump file from production to the specified test server
• issue import commands on the specified test server over SSH and return output
• remove dump file from both servers after complete
• issue some reasonable output for most steps along the way

I would stick as closely as possible to the output of mysqldump like the OP asked, since it includes a slew of information about the view that can't be reconstructed with a simple query from the INFORMATION_SCHEMA.

This is how I create a deployment view script from my source database:

SOURCEDB="my_source_db"
mysql $SOURCEDB --skip-column-names  -B -e \
"show full tables where table_type = 'view'" \
| awk '{print $1}' \
| xargs -I {} mysqldump $SOURCEDB {} > views.sql

Thanks for this - very useful.

One hiccup though - perhaps as I have a slightly convoluted set of views that reference other views etc:

I found that the "definer" user needs to exist and have the right permissions on the target schema, otherwise mysql will not generate the views that reference other views as it things definitions are insufficient.

In the generated:

/*!50013 DEFINER=<user>@<host> SQL SECURITY DEFINER */

--> ensure <user>@<host> is ok on your target instance, or replace this string with a user that does.

Thanks Thorstein