Performance

Words

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• Bulk write

  Saving many rows with one database statement or one transaction, instead of one INSERT and one commit per row.

• Cache stampede

  A popular cache key expires, and every request that arrives before it is filled again misses at the same moment.

• Connection pool

  The app opens a few database connections once and keeps them in a pool.

• Database index

  A sorted copy of one or more columns, each entry pointing to its row, that the database keeps next to a table.

• Distributed trace

  A record of one request as it moves through several services.

• Flame graph

  A picture of a CPU profile: a profiler samples the call stack many times a second, and each function becomes a bar as wide as its share of the samples.

• Memoization

  A function remembers its answer for each input it has seen.

• OOM kill

  A container has a memory limit.

• p99 latency

  The response time that 99% of requests beat: sort the times, and the one 1% from the slow end is p99.

• Streaming results

  The code reads a big result in small pieces, for example 1,000 rows at a time, and finishes each piece before it reads the next.