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@rgreenjr
rgreenjr / postgres_queries_and_commands.sql
Last active May 14, 2025 00:29
Useful PostgreSQL Queries and Commands
-- show running queries (pre 9.2)
SELECT procpid, age(clock_timestamp(), query_start), usename, current_query
FROM pg_stat_activity
WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%'
ORDER BY query_start desc;
-- show running queries (9.2)
SELECT pid, age(clock_timestamp(), query_start), usename, query
FROM pg_stat_activity
WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%'
@MohamedAlaa
MohamedAlaa / tmux-cheatsheet.markdown
Last active May 16, 2025 22:55
tmux shortcuts & cheatsheet

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname
@jboner
jboner / latency.txt
Last active May 18, 2025 13:01
Latency Numbers Every Programmer Should Know
Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference 0.5 ns
Branch mispredict 5 ns
L2 cache reference 7 ns 14x L1 cache
Mutex lock/unlock 25 ns
Main memory reference 100 ns 20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy 3,000 ns 3 us
Send 1K bytes over 1 Gbps network 10,000 ns 10 us
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD