Delete all root mail / inbox on Linux / AWS EC2

In AWS EC2 due to local email notification log file size local disk space will get full

to clear down email log

cat /dev/null > /var/spool/mail/root

MYSQL 5.7 to 8..0 Migration issues I faced

When we migrated our MYSQL 5.7.22 database to 8.0.13 in AWS we have faced following issues

Issue 1: The following objects use the utf8mb3 character set. It is recommended to convert them to use utf8mb4 instead, for improved Unicode support.

Solution 1:

We used following commands to convert all the character type column’s character set to utf8mb4

      a. Following query will generate an alter script for All varchar columns belongs to utf8_unicode_ci collation. Change the database name and run. Take the output and execute into the database to convert

SELECT concat("ALTER TABLE `",table_schema,"`.`",table_name, "` CHANGE `",column_name,"` `",column_name,"` ",data_type,"(",character_maximum_length,") CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;") as _sql  FROM `columns` where table_schema like <> and data_type in ('varchar') and collation_name='utf8_unicode_ci';

     b.Following query will generate an alter script for All text, tinytext, mediumtext, longtext columns belongs to utf8_unicode_ci collation. Change the database name and run. Take the output and execute into the database to convert

SELECT concat("ALTER TABLE `",table_schema,"`.`",table_name, "` CHANGE `",column_name,"` `",column_name,"` ",data_type," CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;") as _sql FROM `COLUMNS` where table_schema like "<>" and data_type in ('text','tinytext','mediumtext','longtext') and collation_name='utf8_unicode_ci';

      c. Following query will generate an alter script for All varchar columns belongs to utf8_general_ci collation. Change the database name and run. Take the output and execute into the database to convert

SELECT concat("ALTER TABLE `",table_schema,"`.`",table_name, "` CHANGE `",column_name,"` `",column_name,"` ",data_type,"(",character_maximum_length,") CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;") as _sql  FROM `columns` where table_schema like <> and data_type in ('varchar') and collation_name= utf8_general_ci ';

      d. Following query will generate an alter script for All text, tinytext, mediumtext, longtext columns belongs to utf8_general_ci collation. Change the database name and run. Take the output and execute into the database to convert

SELECT concat("ALTER TABLE `",table_schema,"`.`",table_name, "` CHANGE `",column_name,"` `",column_name,"` ",data_type," CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;") as _sql FROM `COLUMNS` where table_schema like "<>" and data_type in ('text','tinytext','mediumtext','longtext') and collation_name= utf8_general_ci';

       e.If you are using views, views character columns also will give a similar collation issue.  To address this issue, we can create by using following command will help

SET character_set_client = latin1;

SET character_set_results = latin1;

SET character_set_connection = latin1;

DROP VIEW your_view;

CREATE VIEW your_view as (

    here_goes_your_view_query);

reference link

https://dba.stackexchange.com/questions/8239/how-to-easily-convert-utf8-tables-to-utf8mb4-in-mysql-5-5

https://stackoverflow.com/questions/9422189/why-is-my-view-utf8-and-how-can-i-change-it-to-latin1

Issue2: 

Schema inconsistencies resulting from file removal or corruption

                Following tables show signs that either table datadir directory or frm file was removed/corrupted. Please check server logs, examine datadir to detect the issue and fix it before upgrade

Solution 2:

MySQL Shell's upgrade checker utility checkForServerUpgrade() could incorrectly report a schema inconsistency error for a table whose name included a special character such as a hyphen.

Remove “-“ hypen from table name will solve this issue

Reference link

https://bugs.mysql.com/bug.php?id=94303

Issue 3:  Issues reported by 'check table x for upgrade' command

Solution 3:

Within the view if you are using database reference will get some of the error like No database is selected either we can remove database reference from view/ remove before migrate those view and recreate again after migrate

AngularJS Upgrade (1.4 to1.7)

Step 1. In the command prompt, go to the project folder and run the following command

a. bower init ( it will create a new bower.json file, if already have bower.json file in the same folder remove and run this command)

                b.  bower update ( in the same command prompt run this command. It will update the angular and dependent library)

Step2: uppercase and lowercase methods are removed. Reference link

https://github.com/angular/angular.js/commit/1daa4f2231a89ee88345689f001805ffffa9e7de#diff-1d54c5f722aebc473dbe96f836ddf974

Due that we will get he error message as follows

Uncaught TypeError: b.lowercase is not a function

For workaround we can add following code in app.js file

angular.lowercase=function(string){

  return (typeof string === 'string') ? string.toLowerCase() : string;

 };

angular.uppercase=function(string){

 return (typeof string === 'string') ? string.toUpperCase() : string;

 };

Step3:  After upgrade we will get this error Error: transition superseded 

To resolve this error upgrade angular-ui-router

a.find and update the version of angular-ui-router in bower.json file

 "angular-ui-router": "~0.4.2",

b.  in the command prompt run the following command in the project folder

bower update angular-ui-router

Step 4 .success and .error are removed from angular 1.7, use .then and .catch as follows

folder(https://code.angularjs.org/snapshot/docs/guide/migration#migrate1.5to1.6-ng-services-$http)

find the following each text

.success(function(data, status, headers, config) {

.success(function(data, status, headers, config){

Replace with following text

.then(function(response) {

       var data = response.data;

        var status = response.status;

        var headers = response.headers;

        var config = response.config;

same as the above repeat for following. Find following text one by one

.error(function(data, status, headers, config) {

.error(function(data,status, headers, config){

Replace with following text

.catch(function(response) {

                var data = response.data;

        var status = response.status;

        var headers = response.headers;

        var config = response.config;

Step 5  Error: orderBy:notarray Value is not array-like

[orderBy:notarray] Expected array but received: {"signed":"Completed","sent":"In Progress","draft":"Draft","cancelled":"Cancelled"}

https://code.angularjs.org/1.7.7/docs/error/orderBy/notarray?p0=%7B%22signed%22:%22Completed%22,%22sent%22:%22In%20Progress%22,%22draft%22:%22Draft%22,%22cancelled%22:%22Cancelled%22%7D

in the view file use toArray:false

Merge multiple CSV files into one

Copy all the csv files which you want to merge into one folder. Navigate to the copied folder via command prompt and execute the following command to merge all csv files into one.

Copy *.csv  <>

E.g.: copy *.csv merged.csv