I read that the query planner changes with every release. Was there a change from 8.4 to 9.3 that would account for a major (2 orders of magnitude) difference in execution time for nested views after we upgraded to 9.3?
http://stackoverflow.com/questions/24067543/nested-views-much-slower-in-pg-9-3-4-than-8-4-8 Prod server running Red Hat Enterprise Linux Server release 5.11 (Tikanga) and Pg 9.3.4 on a 2 x 2.33GHZ processor, 24GB of RAM, 900 GB of RAID 5 storage on 6 drive server. Pg configuration: autovacuum,on,configuration file autovacuum_analyze_scale_factor,0.1,configuration file autovacuum_analyze_threshold,50,configuration file autovacuum_max_workers,3,configuration file autovacuum_naptime,1min,configuration file autovacuum_vacuum_cost_delay,20ms,configuration file autovacuum_vacuum_cost_limit,-1,configuration file autovacuum_vacuum_scale_factor,0.2,configuration file autovacuum_vacuum_threshold,50,configuration file checkpoint_completion_target,0.9,configuration file checkpoint_segments,16,configuration file client_encoding,UTF8,session client_min_messages,warning,configuration file DateStyle,"ISO, MDY",configuration file deadlock_timeout,5s,configuration file default_text_search_config,pg_catalog.english,configuration file effective_cache_size,4GB,configuration file from_collapse_limit,8,configuration file geqo_effort,5,configuration file geqo_threshold,12,configuration file hot_standby,on,configuration file lc_messages,en_US.UTF-8,configuration file lc_monetary,en_US.UTF-8,configuration file lc_numeric,en_US.UTF-8,configuration file lc_time,en_US.UTF-8,configuration file listen_addresses,*,configuration file log_connections,on,configuration file log_destination,stderr,configuration file log_directory,/dbms/postgresql/logs/dtfprod,configuration file log_disconnections,on,configuration file log_duration,off,configuration file log_error_verbosity,terse,configuration file log_filename,postgresql-%a.log,configuration file log_hostname,on,configuration file log_line_prefix,< %m %u %d %h >,configuration file log_min_error_statement,error,configuration file log_min_messages,error,configuration file log_rotation_age,1d,configuration file log_rotation_size,100MB,configuration file log_timezone,US/Pacific,configuration file log_truncate_on_rotation,on,configuration file logging_collector,on,configuration file maintenance_work_mem,256MB,configuration file max_connections,200,configuration file max_stack_depth,8MB,configuration file max_wal_senders,5,configuration file port,5432,configuration file random_page_cost,2,configuration file shared_buffers,2GB,configuration file ssl,on,configuration file stats_temp_directory,pg_stat_tmp,configuration file temp_buffers,16MB,configuration file TimeZone,US/Pacific,configuration file track_activities,on,configuration file track_activity_query_size,1024,configuration file track_counts,on,configuration file track_functions,none,configuration file track_io_timing,off,configuration file update_process_title,on,configuration file wal_keep_segments,1920,configuration file wal_level,hot_standby,configuration file wal_sender_timeout,1min,configuration file wal_sync_method,fdatasync,configuration file work_mem,5MB,configuration file thanks, PasDep