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Hosting Operations

Read-only, sensitive output

Find Long-Running MySQL Queries

MySQL is slow and you need to identify queries that have been running the longest.

Command

mysql -e "select id,user,host,db,command,time,state,left(info,80) as info from information_schema.processlist where command <> 'Sleep' order by time desc limit 10;"

Before you run this

System impact: Read-only. Output may expose users, paths, tokens, keys, IPs, process arguments, or log details.

When not to use it: Do not assume every long-running query is unsafe; verify owner and purpose first.

Expected output

A sorted list of active MySQL sessions with runtime and query prefix.

System impact

Read-only, sensitive output. Nothing changes. MySQL prints active non-sleeping sessions sorted by age.

Recovery / rollback: no state is changed.

When to use it

Use during latency spikes, stuck reports, and migration incidents.

When not to use it

Do not assume every long-running query is unsafe; verify owner and purpose first.

next steps

Related commands

Hosting Operations Read-only

Find Long-Running PostgreSQL Queries

One query can make the whole app look broken.

psql -X -c "select pid, now() - query_start as age, state, left(query, 80) as query from pg_stat_activity where query_start is not null order by age desc limit 10;"
Hosting Operations Read-only

Check PostgreSQL Lock Waits

The outage was a queue, not a crash.

psql -X -c "select pid, wait_event_type, wait_event, state, left(query, 80) as query from pg_stat_activity where wait_event_type is not null order by pid;"
Hosting Operations Sensitive output

Show MySQL Database Sizes

The storage alert needed a database name.

mysql -e "select table_schema, round(sum(data_length + index_length)/1024/1024, 1) as mb from information_schema.tables group by table_schema order by mb desc;"
Hosting Operations Read-only

Show Active PostgreSQL Connections

The database was not down. It was full.

psql -X -A -F '|' -c "select pid,usename,datname,state,client_addr from pg_stat_activity order by state, pid;"
Hosting Operations Sensitive output

Show Active MySQL Sessions

The app was waiting behind busy sessions.

mysql -e "show full processlist;"
Study mapping

Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.

  • LPIC-1 style command-line practice
  • LFCS style performance-task practice
  • Linux+ style troubleshooting review

Independent study support only. No affiliation, endorsement, exam dumps, or real exam questions.