PostgreSQL interview questions part2

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 Explain about the PostgreSQL architecture 

Background process 
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  • postmaster process  : Listens for incoming connection
  • postgres process  :  for every connection a new postgres process is created. 
  • Stats collector  : for collecting statistics 
  • Autovaccum process  : For vaccuming. 
  • Background writer : For writing DB files
  • WAL writer : for writing WAL/log files


Memory Structure:
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  • Shared_buffers
  • Work_memory 
  • Temp_memory
  • maintenance_work_mem 
  • autovacuum_work_mem 
Logical Structure
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Cluster which consists of database, users and tablespaces. Each database consist of schemas and tables.

Physical Layout:
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 Background folders and files 
Base , global, pg_wal/pg_xlog , pg_clog etc 
Files: postgresql.conf, pg_hba.conf, postmaster.pid  




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