I have a question, about the internal handling of array columns in Postgres. Does the engine handle it as a classical array with memory alloc or is it somehow a pointer list.

It would be interesting to know - I have a few questions to answer myself concerning performance... :)

  • 3
    Why not take a look at the source code? Or, possibly, you could ask this on a postgresql list as well.
    – dezso
    Nov 9 '12 at 16:48

Arrays are defined in src/includes/utils/array.h and src/backend/utils/adt/arrayfuncs.c and the other array* files in src/backend/utils/adt/.

An array is a VARLENA (see src/backend/utils/adt/varlena.c) which is a palloc()'d type, a scoped-storage wrapper around malloc(). Arrays are block-allocated data, not linked lists.

  • 1
    Good to have PostgreSQL expertise from specialists with a source code level understanding of RDBMS on DBA.SE, right? :)
    – dezso
    Nov 10 '12 at 8:27

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