I wanted to find out how many rows were modified by the current transaction. Seems like MariaDB doesn’t have a straight forward way to retrieve the transaction ID. To narrow down transactions I used the current connection as the thread ID. You can run the below command to check the information about the transaction.
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SELECT * nFROM information_schema.innodb_trx nWHERE trx_mysql_thread_id = CONNECTION_ID() \Gnnn
Here is an example:
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Missing Images
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If you have Terraform state locks. Sometimes cancelling terraform commands ungracefully might leave the state file locked. This is the error you would usually see if the lock is not released.
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Acquiring state lock. This may take a few moments...nnError: Error locking state: Error acquiring the state lock: ConditionalCheckFailedException: The conditional request failedn status code: 400, request id: L2CH7KK3QCAEHSC1TJ1VLBMNBRVV4CQNSO5AEMVJY66Q9ASUAAJNnLock Info:n ID: 21e2b2bb-c123-2383-eece-7a5eaab4f645n Path: s3/path/to/the/state/filen Operation: OperationTypePlann Who: username@hostnamen Version: 0.11.14n Created: 2020-02-11 11:26:58.602608 +0000 UTCn Info:nnnTerraform acquires a state lock to protect the state from being writtennby multiple users at the same time. Please resolve the issue above and trynagain. For most commands, you can disable locking with the "-lock=false"nflag, but this is not recommended.nnn
If you want to release this lock. You should run below command. Then type “yes” and hit enter.
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$ terraform force-unlock <LOCK ID>nnn
For example:
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$ terraform force-unlock 21e2b2bb-c123-2383-eece-7a5eaab4f645nnn
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Warning: Please don’t release this lock, unless you are the once who caused it. It might corrupt the state file.
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I am writing this post as a note to myself. Every time I want to find slow running queries, I search and open this medium post. It is a well written short post which helps me every day. But I wanted to improve that query.
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SELECTn pid,n now() - pg_stat_activity.query_start AS duration,n query,n statenFROM pg_stat_activitynWHERE (now() - pg_stat_activity.query_start) > interval '5 minutes' nORDER BY duration DESC;nnn
As mentioned these are pretty helpful too.
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SELECT pg_cancel_backend(pid);nSELECT pg_terminate_backend(pid);nnn
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I wanted to know how to run a command after creating an RDS instance with Terraform. This was the answer I got from AWS. Even though, Terraform shouldn’t be used like this.
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resource "aws_db_instance" "mydb" {n engine = "mysql"n engine_version = "5.6.40"n instance_class = "db.t1.micro"n name = "initial_db"n username = "example"n password = "1234"n allocated_storage = "20"n publicly_accessible = "true"n}nnoutput "username" {n value = "${aws_db_instance.mydb.username}"n}nnoutput "address" {n value = "${aws_db_instance.mydb.address}"n}nnresource "null_resource" "test" {n depends_on = ["aws_db_instance.mydb"] #wait for the db to be readyn provisioner "local-exec" {n command = "mysql -u ${aws_db_instance.mydb.username} -p${aws_db_instance.mydb.password} -h ${aws_db_instance.mydb.address} -e \"CALL mysql.rds_set_configuration('binlog retention hours', 24);\" "n }n}nnn
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I couldn’t write anything down for a while. I had to move a table from one schema to another in PostgresSQL. I had to do this on RDS. pg_dump and pg_restore tools doesn’t allow you to change schema when you dump and restore.
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The easiest way is running below command:
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ALTER TABLE old_schema.table_you_want_to_move SET SCHEMA new_schema;nnn
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I upgraded to Catalina last week. I have three major issues with the new version.
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Screenshots app doesn’t work
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I ruled down the screenshot issue is due to new permission scheme. But I couldn’t find a fix. But I found a workaround. I use screenshots to share with Slack usually, but it might not work for you.
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Press CMD+Space.
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Click on “Option” and select Clipboard. Next time when you want a screenshot use usual shortcuts CMD+Shift+3 or CMD+Shift+4 and paste on Slack chatbox or Word document.
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Dock is gone
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There are two solutions to this problem. First is running below command in the shell.
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$ defaults delete com.apple.dock; killall Docknnn
or
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CMD+Option+D
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Notifications don’t work
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Open “System Preferences”. Click on “Notifications”. Select the application you want notifications from. Click “Allow Notifications from <Application Name>”
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I ran a few update queries against a MySQL database. Update command said it updated some records. But data didn’t seem to be as we expect. Let’s say the table looked like below.
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I ran a query which is similar to below.
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UPDATE update_test SET age = 30 AND name = 'John' WHERE id = 1;nnn
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MySQL prompt says that it managed to update one row. But if you look at the data after the update query, it will be clear that age is not 30 or neither the name is ‘John’. This is because the query is interpreted as an expression.
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UPDATE update_test SET age = (30 AND name = 'John') WHERE id = 1;nnn
Let’s look at another query.
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UPDATE update_test SET age = 30 AND name = 'Larry' WHERE id = 3;nnn
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The output says it didn’t update any records because age is already 0 and our update query is actually trying to set it as 0. Replacing AND with “,” will set both fields.
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UPDATE update_test SET age = 30, name = 'Larry' WHERE id = 3;nnn
With this expression evaluation, we can write advance update queries. For example, I am going to update student data. My update query should update the highest_mark field from the highest value of eng_marks or sci_marks field. Both eng_marks and sci_marks should be higher than 50 too. The query looks like below.
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UPDATE students SET highest_mark = IF(eng_marks > sci_marks, eng_marks, sci_marks) WHERE eng_marks > 50 AND sci_marks > 50;nnn
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Thanks a lot, Ross for helping to figure this out!
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I bought a Xiaomi Redmi Note 7 with MIUI Version: 10.3.5. I was not very happy with the preinstalled apps. So I tried to remove them using “adb”. I accidentally deleted some app I shouldn’t delete.
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Everything was fine until I restart the device. When I restarted it, it was caught in a boot loop. I had to find a way to fix my phone.
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Warning: IF YOU FOLLOW THESE INSTRUCTIONS YOU WILL LOSE ALL YOUR DATA!
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I repeat again this will wipe all your data. Luckily everything was backed up in my mobile. There was nothing I couldn’t recover.
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Press the volume up button and power button together for a few seconds.
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It will boot up to the recovery menu.
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You can navigate using volume up and down buttons. Press the volume down button to select “Wipe Data”. Press the power button.
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Press the power button again. Then select the “Confirm” option and press the power button again
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Now we need to reboot back to the system. Select the “Reboot” option and press the power button.
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Select the “Reboot to system” and press the power button again.
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It may take a while to start the phone. Now all your data is wiped and the system is restored. Now you have to log in and set up!
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We are living in an age where we would love to experience better predictions. Predictions can come in many ways. The simplest example is the recommendations. Amazon, Netflix and Spotify recommend it all the time. They provide impressive recommendations. Everybody loves when AI/ML makes our lives easier. It can be recognizing faces or showing you the news you want to see.[1] We have systems which beat specialists. [2]
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Meanwhile, on the other hand, everybody worries about privacy. Corporations pay billions of dollars to settle so-called privacy-related disputes.[3] People are concerned about privacy more than ever.
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On the contrast, we need more data to improve AI. Should we compromise? Is curing cancer more important than individual privacy? Can pseudo-anonymous data help to overcome these challenges? [4] No matter how we anonymous data, we will have the signature of the individuals. A better AI always can crack and get back to individuals.[5]
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Where are we going to draw the line?
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[1] – https://www.facebook.com/help/122175507864081
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[3] – https://www.bbc.com/news/business-49099364
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[4] – https://www.nytimes.com/2019/07/23/health/data-privacy-protection.html
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[5] – https://gizmodo.com/in-the-closet-lesbian-sues-netflix-for-releasing-her-mo-5429348
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If you want to see the current schema you are on.
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SHOW SEARCH_PATH;nnn
Normally you might be on the public schema. But if you want to change the current schema, try below command.
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SET SEARCH_PATH TO test;nnn
test is the name of the schema.
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