PostgreSQL

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Note that if you make -N larger than 32, you must also increase -B beyond its default of 64; -B must be at least twice -Nand probably should be more than that for best performance. For large numbers of backend processes, you are also likely to find that you need to increase various Unix kernel configuration parameters. Things to check include the maximum size of shared memory blocks, SHMMAX; the maximum number of semaphores, SEMMNS and SEMMNI; the maximum number of processes, NPROC; the maximum number of processes per user, MAXUPRC; and the maximum number of open files, NFILE and NINODE. The reason that PostgreSQL has a limit on the number of allowed backend processes is so your system won’t run out of resources.


In PostgreSQL versions prior to 6.5, the maximum number of backends was 64, and changing it required a rebuild after altering the MaxBackendId constant in include/starage/sinvaladt.h.


3.13) What are the pg_sorttempNNN.NN files in my database directory?


They are temporary files generated by the query executor. For example, if a sort needs to be done to satisfy an ORDER BY, and the sort requires more space than the backend’s -S parameter allows, then temporary files are created to hold the extra data.


The temporary files should be deleted automatically, but might not if a backend crashes during a sort. If you have no backends running at the time, it is safe to delete the pg_tempNNN.NN files.

Operational Questions


4.1)    Why is the system confused about commas, decimal points, and date formats?

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